In this paper, a hypothetical district representing the typical urban districts in Hong Kong was considered and a district cooling system model was designed for this district. Mathematical models were tailor-designed for all the major district cooling system equipment to simulate the effects of changing the pumping station’s configuration on the energy performance of the district cooling system. The measures included the use of multiple pumping stations and an unequal number of pumps in each station. In view of the vast number of pumping station combinations possible for analysis, a hydraulic gradient evaluation method was adopted to assist a quick assessment and exploration of those combinations that would be technically feasible. Furthermore, the energy performance of all these technically feasible combinations was evaluated to identify an optimum design that would lead to the lowest electricity consumption.
Practical application: In a district cooling system where there is only one main pumping station for distributing chilled water to all the buildings in the district, the chilled water flow rate and pressure head are very high. Adding booster pumping stations can help to reduce pressure head, pump size and hence power demand of the main pumping station. In this paper, the effects of different pumping station configurations on the energy performance of a district cooling system were investigated. The configuration that could mitigate the impacts of a low delta-T on the energy performance of the district cooling system was also identified.
In the UK, there are approximately 330,000 holiday homes spread across a large number of mainly privately owned sites. These homes are often sited in exposed locations, are poorly insulated and are generally heated using expensive fuels, such as electricity or LPG. There is also a lack of empirical evidence available on the in situ energy performance of these homes. Consequently, it is not possible, given the existing evidence base, to determine whether these homes suffer from the same scale of building fabric thermal ‘performance gaps’ (between assumed and realised in situ performance) that have been documented for newbuild UK housing. This paper presents the results obtained from undertaking detailed in situ thermal fabric tests on five new holiday homes. Whilst the size reported here is small, the results indicate that a ‘performance gap’ exists for all of these homes. Results obtained indicate that this gap appears narrower than that documented for newbuild UK housing. The results also suggest that the scale of the ‘gap’ may be more a consequence of the way in which the design intent of these homes has been determined, i.e. a ‘prediction gap’.
Practical application: This paper presents the results obtained from undertaking detailed building fabric thermal performance tests on a small sample of new holiday homes. The results of these tests indicate that although a building fabric thermal performance ‘performance gap’ exists in all of the holiday homes tested, the results suggest that the ‘gap’ is much smaller than that documented for new build UK housing and may be more of a consequence of the way in which the design intent of these homes has been determined, i.e. a ‘prediction gap’, rather than a ‘performance gap’ between assumed and realised in situ performance. These results could be used by industry to develop more appropriate prediction tools that are relevant to holiday homes.
Saudi Arabia’s energy consumption is increasing astronomically. Saudi Building Code prescribes a fixed base temperature of 18.3℃ to estimate the heating degree-days and cooling degree-days. Using historical meteorological data (2005–2014), this article presents the heating degree-days and cooling degree-days estimated for the representative cities in all the five inhabited climatic zones of Saudi Arabia. We used the base temperatures of 14℃, 16℃ and 18℃ for heating degree-days, and 18℃, 20℃, 22℃, 24℃ and 28℃ for cooling degree-days for Dhahran, Guriat, Jeddah, Khamis Mushait and Riyadh cities. We developed multiple regression models for heating degree-days and cooling degree-days at various base temperatures for these zones. Degree-days for other cities in similar climates with limited input data can be computed with these. Lowering of base temperature by 2 K from 18℃ reduced the heating degree-days by 33–65%. At 14℃ of base temperature, the heating requirement reduced by 60–95%. Elevating the base temperature by 2 K from 18℃ lowered the cooling degree-days by 16–38%. At 28℃ of base temperature cooling can be completely eliminated in Khamis Mushait, and reduced by 65–92% in other cities. This observation merits rethinking about use of appropriate base temperatures that properly link the outdoor environment to reduce the energy consumption.
Practical application: Using historical data, we developed regression models for predicting heating and cooling degree-days for five cities of Saudi Arabia in various climate zones without the historic data. Using these, we can estimate the changes in heating/cooling load due to the variation in base temperatures. For example, lowering base temperature by 2–4 K from 18℃ reduces the HDDs by 33–95% and elevating the base temperature by 2–4 K from 18℃ lowered the CDDs by 16–68%.
Heat exchange between chilled food storage and conditioned spaces in large food retail stores is not currently required as part of design stage regulatory compliance energy performance models. Existing work has identified that this exchange has a significant impact on store energy demand and subsequently leads to unrealistic assessment of building performance. Research presented in this article uses whole building dynamic thermal simulation models that are calibrated against real store performance data, quantifying the impact of the refrigeration driven heat exchange. Proxy refrigerated units are used to simulate the impact of these units for the sales floor areas. A methodology is presented that allows these models to be simplified with the aim of calculating a realistic process heat exchange for refrigeration and including this in thermal simulation models; a protocol for the measurement of chilled sales areas and their inclusion in the building models is also proposed. It is intended that this modelling approach and the calculated process heat exchange inputs can be used to improve the dynamic thermal simulation of large food retail stores, reduce gaps between predicted and actual performance and provide more representative inputs for design stage and regulatory compliance energy calculations.
Practical application: The modelling methodology and research findings presented in the article are of practical use for building energy modelling engineers using dynamic simulation models to design and/or evaluate the energy performance of large food retail stores. The methodology can be used in the design of new facilities or the evaluation of large scale retrofit projects. It is also of practical interest to energy and facility managers within large food retail organisations as it will aid their understanding of applied energy performance models.
In the UK, approximately 16% of the energy use can be attributed to domestic wet central heating systems. Government financial support and advances in technology have led to boilers becoming more efficient and a range of technologies are now available that claim to be able to improve the efficiency of domestic wet central heating systems. One such low cost technology is a passive deaerator. This article presents the results obtained from installing a passive deaerator on the closed loop of a gas-fired wet central heating system, under controlled conditions in the Salford Energy House. The results indicate that although marginally less heat output was required from the boiler when the passive deaerator was operating, these savings are more or less out weighted by the boiler short cycling more frequently. Consequently, the overall reduction is gas consumption achieved by utilising the passive deaerator device is only of the order of 0.5%; this scale of savings may just be a consequence of measurement noise. The implications are that although a marginal benefit may be attributed to these products, if short cycling takes place, then these savings may become insignificant.
Practical application: This article describes a test method that has been used to quantify the energy savings that could be achieved by installing a passive deaerator on the closed loop of a wet central heating system. Although the results indicate that the energy savings associated with using such a device are likely to be marginal, the test method described could be used to test a range of other devices that claim to improve the performance of domestic wet central heating systems, to directly compare before and after performance.
Building performance simulation requires representative weather data of specific locations. Test Reference Year (TRY) and Typical Meteorological Year (TMY) are common hourly dataset for typical year conditions. In sub-tropical climates, overheating is very common in buildings due to high temperature and intense solar radiation. However, there are no universal approaches to develop a dataset for estimating summer discomfort in naturally ventilated and free-running buildings. This article employs the concept of Summer Reference Years (SRY) in order to represent the near-extreme summer conditions in Hong Kong. The derived SRY is able to capture the near-extreme conditions in the multi-year series. The SRY was found to represent the high Tdry values reasonably well during daytime when such near-extreme conditions occur. On the contrary, according to the number of HN-DHs, the SRY does not satisfactorily represent high night-time Tdry. It is possible to incorporate the sorting of Tdry-min in the SRY adjustment in order to better reflect night-time situations in sub-tropical climate. Further studies are therefore required to confirm whether such modifications give more accurate results in the assessment of building energy performance. Nonetheless, the SRY dataset can be applied in building performance simulation and the assessment of indoor thermal comfort.
Practical application : The present study found that there are deficiencies for the SRY to represent the high night-time Tdry, which affects the building performance assessment in sub-tropical climates. It suggests potential improvement to the existing adjustment of SRY for representing the near-extreme summer conditions in order to obtain more accurate results of building assessment.
Robust energy management in buildings is addressed in this paper. The energetic impact of buildings in the current energetic context is first presented. Then the studied optimization problem is defined as the optimal management of production and consumption activities in buildings. A scheduling problem is identified to adjust the energy consumption to both the energy cost and the user’s comfort. The available flexibility of the services provided by domestic appliances is used to compute optimal energy plans. These flexibilities are associated to time windows or heating storage abilities. A constraints formulation of the energy allocation problem is given. A derived mixed linear program is used to solve this problem. The energy consumption in houses is very dependent on uncertain data such as weather forecasts and inhabitants’ activities. Parametric uncertainties are introduced in the home energy management problem in order to provide robust energy allocation. Robust linear programming is implemented. A scenario-based approach is implemented to face this robust optimization problem.
Practical application : Because of the increasing part of renewable energy in electricity production, which is difficult to control, consumers will have to become more involved in the grid management. This paper states the problem of energy management in buildings and describes the optimization problem defined to adjust the energy consumption of buildings to production constraints. This decision system is based on the weather forecasts and a variable cost of electricity. Parametric uncertainties on the data are taken into account in order to propose robust energy planning in which a performance is guaranteed over the expected data.
Double-deck elevators are a very efficient mode of transport, especially in high rise buildings. This is due to the fact that they reduce the number of stops in a round trip (leading to a smaller value of the round trip time hence a higher handling capacity) and take up less space of the core of the building leading to high space usage efficiency. This paper provides a comprehensive treatment of the double-deck elevator traffic calculations. It derives an exact set of equations to find the value of the round trip time under incoming traffic conditions, for the cases of equal and unequal floor populations. Moreover, equations have also been derived for two performance coefficients. The first coefficient is called the passenger transfer efficiency coefficient and is representative of the time taken by passenger to alight from the double-deck elevator. The second coefficient is called the coincidental stopping coefficient and is representative of the stopping efficiency. All the results from the equations have been verified using the Monte Carlo simulation method. The method of stepwise verification has been used in order to verify the equations. Under stepwise verification, the equations are derived in stages and each stage is verified against the results from the Monte Carlo Simulation method. The paper ends by suggesting methods of dealing with two of the irregular conditions. Namely two cases are discussed: the case where the number of floors above the main entrance is odd; and the case where the floor heights are unequal and the rated speed is not attained in one double floor journey.
Practical application : This paper presents a full set of equations that allow the elevator system designer to fully assess the expected performance of the double-deck elevator system under incoming traffic conditions. These equations (manually or within a software program) can be used to carry out a full design (thus selecting the number, speed, and capacity of the double-deck elevators).
Owing to the limited installation space and duct size, coupled fittings are common in the duct systems of buildings. The coupling effect leads to changes in drag and fan energy consumption. This study investigates duct drag and flow field characteristics under coupling conditions. Experiments and numerical simulations with the Reynolds stress model are conducted. Flow field changes, flow field deformation, and drag changes in the duct are analyzed. Regardless of the coupling form, the velocity near the inner arc is fast, whereas that near the outer arc is slow. Under three different coupling connection conditions (S-shaped, L-shaped, and U-shaped), the outlet velocity gradient of the U-shaped coupling connection is the least obvious. After the fluid flows through the bend, a significant centerline velocity reduction can be observed, even greater than that in the bend. The lowest centerline velocity lies within the range of 2.5 D to 4.5 D after the bend. Coupling connection has an insignificant effect on upstream duct resistance. The resistance of single bend is less than that of the downstream bend for the coupled bend and greater than that of the upstream bend under coupling conditions.
Practical application : Coupling effect is common in practical application of ventilation engineering. This effect leads to the change of fluid resistance loss of ducts and pipes. However, few researchers focus on this effect. This study finds that regardless of the coupling form, the velocity near the inner arc is fast, whereas that near the outer arc is slow. It means the guide vane should be set near inner arc. L-shaped coupling connection has the largest downstream piping resistance. The resistance of the downstream piping under S-shaped coupling is the least, thus L-shaped coupling connection should be avoided as far as possible in practical application.
As a form of task/ambient conditioning (TAC) system, task ventilation is an effective way to control the micro environment of workplace. In response, we have proposed and investigated a radiant floor cooling combined with desk-based TAC system in order to accomplish complementary advantages of radiant floor system and TAC system. Up to now, very few studies on this system have been found in existing literatures. In this paper, appropriate working parameters of the system are examined by numerical simulation method. To improve simulation accuracy, experiments were simulated in reference by applying three turbulence models and two radiation models. It turned out that the standard k– model combined with Discrete Ordinates (DO) model boasts the best accuracy as is revealed by the comparison between simulated results with the experimental. On this basis, a simulation of an office adopting the system was performed. According to analysis of the influence of different radiant panel temperatures and air supply parameters of TAC system on the thermal environment based on calculated results, the appropriate working parameters that meet the thermal comfort requirements are obtained, which can be used as a reference for the design of the system. The TRNSYS software was employed to simulate the operation energy consumption of the composite system in the office building, and the design parameters of the comprehensive consideration of comfort and energy saving are put forward in the present study.
Practical application: For the conference room applied a radiant floor cooling combined with TAC system, this paper analyzed the impact of floor surface temperatures, task air supply temperature and task air supply temperature to the occupants workplace’s thermal environment and energy consumption of the system, and obtained the design parameters which comprehensive considered comfort and energy consumption. The research results of this paper can provide guideline for the design and selection of the working parameters for the conference room applied a radiant floor cooling combined with TAC system.
In the liquid desiccant system, the amount of the diluted solution sent to the regenerator has a great influence on the system performance. The liquid desiccant system with an adjustable reflux ratio of regeneration solution was proposed in the paper, and the effect of the solution regeneration reflux ratio on the system performance was analysed by simulation. The energy consumption, the electric coefficient of performance and the thermal coefficient of performance under different water condensation rates and varied solution regeneration reflux ratio were obtained. The results show that, the overall performance of the liquid desiccant system can be improved by reducing the solution regeneration reflux ratio; a 1% decrease in the reflux ratio leads to a 0.56–1.02% average growth rate of electric coefficient of performance and a 0.51–0.95% average growth rate of thermal coefficient of performance. Moreover, when the regeneration temperature is high and the water condensation rate of the process air is low, the improvement from decreasing the solution regeneration reflux ratio is more significant. However, the reflux ratio cannot be reduced to an unlimited extent. There is a rational optimum range of the reflux ratio to achieve high thermal coefficient of performance, the optimum range under low dehumidifying load is different from that under high load.
Practical application: The performance of a liquid desiccant system can be improved by the proposed system configuration with an adjustable reflux ratio of regeneration solution, such novel system configuration could be applied for the design of air conditioning system, which is beneficial for the energy saving in building. Moreover, the rational optimum ranges of the reflux ratio to achieve high coefficient of performance under different dehumidifying loads are obtained, which could provide guidelines for the design and operation management of the liquid desiccant based building air conditioning system.
This research will assess the effectiveness of glass solar chimney wall by open frame (GSCW-O) and compare it with one-layer glass wall (OLGW) in Thailand. The results showed that the use of a GSCW-O can reduce the inside temperature compared with that of OLGW by around 2–4℃ annually, providing heat transfer to the outside, as well as limiting the relative humidity (RH) to 60%, which protects against the occurrence of fungi that cause allergies. The research also found that GSCW-O results in 10–20% less energy consumption when compared to OLGW. In addition being five times cheaper than insulation glass, the payback period for GSCW-O is only 5–6 years. The questionnaire results were satisfactory and proved GSCW-O is very good in practice, pleasing in design, and providing significant energy savings. Testing of hydroponic cultivation in a GSCW house also showed satisfactory growth with a lack of pests, resulting from controlled temperature, humidity, and protection from the elements. For a tropical climate such as Thailand’s, GSCW-O is a suitable design for the reduction in energy consumption and for sustainable architecture.
Practical application This research provides helpful information on glass solar chimney wall by open frame for both the owners and developers by adopting an energy efficient building for sustainable energy conservation. For tropical country like Thailand, glass solar chimney wall by open frame is a suitable design and the best alternative for saving energy and global environmental conservation in the building industry.
Bioclimatic architecture strategies and solar active systems contribute strongly to the reduction of building energy demand and achieving thermal comfort for its occupants over the whole year. This paper deals with the study of the energy performance improvement of a pilot bioclimatic house located in Algiers (Algeria). First, a series of experimental measures are conducted during cold period to show the effect of passive and active solar gains on the improvement of the indoor air temperature of the house. Then, a dynamic model of a solar heating system coupled with a bioclimatic house has been developed using TRNSYS software and validated with experimental data. The validated model has been used to establish the energy balance of the pilot bioclimatic house without solar heating system and to compare them to those of a conventional house. Finally, the improvement of the energy balance of the pilot bioclimatic house has been done by passive and active ways. The passive one includes the increase of south facing windows size and the use of night cooling with the use of shading device in summer. The active one consists of the integration of a solar heating system. Furthermore, an environmental study has been performed. The experimental results show that the energy requirements of a pilot bioclimatic house are very low which is suitable for the use of solar heating system in building. The simulation results show that the application of bioclimatic strategies is a better way to provide thermal comfort in summer and decrease the space heating energy demand of the house with 48.70%. The active solar system will cover 67.74% of the energy demand for heating of the house. These energy savings generate a significant reduction in CO2 emissions.
Practical application : This work will enable engineers and designers of modern buildings of buildings in a Mediterranean climate to improve building energy efficiency and reduce CO2 emissions by a conjunction of different passive heating and cooling techniques such as insulation, thermal mass, window shades, night ventilation, and the solar heating system. The paper provides designers an effective strategy in terms of energy savings and indoor thermal comfort while reducing CO2 emissions.
Peak demand cost usually contributes a large proportion of the total electricity bills in buildings. Using existing building facilities for power demand limiting has been verified as effective measures to reduce monthly peak demands and associated costs. Fire service water tanks exist in most commercial buildings. This paper presents a comprehensive study on how to effectively retrofit existing building fire service water tanks as chilled water storage for power demand limiting. Important technical and economic factors that may affect the implementation of the proposed retrofitting are addressed. Two retrofitting schemes, i.e. a small T (storage temperature difference) scheme and a large T scheme are proposed for integrating the chilled water storage system into an existing all-air system and an existing air-water air conditioning system, respectively. Two optimal demand limiting control strategies, i.e. time-based control and demand-based control, are proposed for maximizing the monthly peak demand reduction of buildings with regular and variable peak occurring time, respectively. The cost-effectiveness of different retrofitting schemes in three real buildings in Hong Kong is analysed. Results show that substantial cost savings can be achieved with short payback periods (0.7–2.6 years) for the retrofits in these three buildings.
Practical application: This paper presents a techno-economic analysis on retrofitting existing building fire service water tanks as chilled water storage for power demand limiting and operational cost saving. The proposed retrofitting schemes and demand limiting control strategies enable chilled water storage systems to be readily applied to most existing buildings. Building owners can benefit from the peak demand cost saving as the monthly peak demand can be significantly reduced by using chilled water storage. The extra costs involved in tank retrofits and system integrations can be paid back within three years.
The importance of atmospheric down-welling radiation in studying building thermal environments and energy performance has been well identified, and empirical formulae to evaluate atmospheric down-welling radiation values developed with their inadequacies. In this paper, a study of developing an alternative general method for evaluating atmospheric down-welling radiation values to the water pond-based empirical formula by Clark and Allen is reported. The validity of the alternative general method has been demonstrated by comparing the atmospheric down-welling radiation values evaluated using the alternative general method and that using the Clark and Allen’s formula. Since the alternative general method developed is based on a building roof system, and no water is involved, the alternative general method developed in this paper appears to have more advantages. On one hand, this could eliminate any potential impacts on prediction accuracy when water is used in different climates. On the other hand, the application of the alternative general method is relatively easier as only a suitable existing roof system is required. Therefore, the use of alternative general method can provide a more reliable and economic alternative in evaluating atmospheric down-welling radiation, when compared to using Clark and Allen’s empirical formula.
Practical application The alternative general method developed for evaluating atmospheric down-welling radiation values in this paper could be used as an alternative to the empirical formula proposed by Clark and Allen and is valid for all climate conditions and easy to be implemented to evaluate alternative general method values. It can be used when evaluating building night sky cooling, building passive cooling system, etc.
The urban heat island intensity is the difference in temperature between a site close to the centre of a city and a site close to but outside the city (the rural site). The urban heat island intensity varies continuously throughout the day and is strongly dependent on the weather conditions at the time. The most important weather parameters are the wind speed, the cloud cover and the solar radiation. We have developed an empirical model for the urban heat island intensity and applied it to a site near the centre of Manchester and a rural site at Rostherne, approximately 17 km away. Weather data from the Met Office station at Rostherne are available from the British Atmospheric Data Centre. Our model uses the measured wind speed, the measured cloud cover and the measured solar radiation from Rostherne. The parameters of the model are adjusted to give a best fit to the measured urban heat island intensity for the year 2014. The model is then used to predict the hourly urban heat island intensity for the first six months of 2015, obtaining good results especially as the values of the parameters are not changed throughout the year and the model does not make use of the temperatures at either site. The accuracy of the model is such that if used for a basic heating and cooling load calculations the accuracy of the annual demand is high.
Practical applications Many buildings that building services engineers and other building designers design are in urban or city centres. However, the weather data for their designs are based on near-rural weather data which do not include the urban heat island effect. This paper describes a method to ascertain the urban heat island effect in the centre of Manchester. A designer could apply this for Manchester and as an initial indication to other similar urban areas. This will allow the rural weather data to be adjusted on an hourly basis for the urban heat island effect throughout the year.
Potential bioaerosol infection risk associated with toilet flushing has not been sufficiently addressed in the design of residential washroom exhaust system. This study evaluates the performance of exhaust ventilation for residential washrooms in terms of air change rate, washroom size, washroom geometry, and locations of door louver, exhaust and water closet. Three bioaerosol species namely Escherichia coli (ATCC 10536), Serratia marcescens (ATCC 6911), and Cladosporium cladosporioides (ATCC 16022) are included in the simulations. By shortening the distance between the locations of exhaust and emission source (i.e. water closet), the fractional counts of bioaerosol particles exhausted can be increased. An increased air change rate and a louvered door can also improve the exhaust ventilation performance, yet with a longer time to steady state. This study should provide a useful source of reference for washroom exhaust designers to minimize bioaerosol infection risk.
Practical application: This paper shows for residential washroom with an exhaust fan installed, the ventilation performance can be improved by an increased air change rate, and by shortening the distance between the locations of exhaust and emission source.
An attachment-based personalized ventilation method, different from the traditional personalized ventilation methods in mechanisms, is presented in this study to improve the micro-environment surrounding a human body. To identify the airflow characteristics of this personalized ventilation method, field measurements were performed to examine the air distribution via the airflow fields near the body. Three factors on the airflow fields under the personalized ventilation method were analyzed in this study, including the supplied air velocity, the horizontal distance between the air outlet and the human body, the vertical distance between the air outlet and the head of the man. According to the measurements in this study, the results show that the higher the supplied air velocity, the more easily the air attachment is formed. For a certain horizontal distance and a certain vertical distance, air attachment is formed only when the supplied air velocity is greater than a critical supplied air velocity. That critical supplied air velocity is an increasing function of the horizontal distance. When the horizontal distance reaches 0.3 m and regardless of the value of the supplied air velocity, air attachment cannot be formed. In addition, the critical supplied air velocity decreases with the vertical distance. Based on the field measurements, design parameters of the personalized ventilation method are analyzed to achieve optimization.
Practical application: A novel personalized ventilation method, which is based on air attachment, is introduced in this paper. Such a personalized ventilation method can be applied to the worktable in factory, office, kitchen, and so on. The experimental results indicate that the novel personalized ventilation method can meet the requirements of fresh air in breathing zone and provide an acceptable thermal comfort for occupants under certain conditions.
This paper presents a new paradigm for assessing the effectiveness of up-peak elevator group control algorithms. The new paradigm can be very effective in providing a mechanism for objectively assessing and comparing elevator group control algorithms. It is built around three essential components: idealised optimal benchmarks; random scenario testing; and progressive introduction of reality. An idealised optimal benchmark is the starting point for calculating an analytical upper bound for the performance of any algorithm. It provides a reference for comparing the performance of all algorithms. Random scenario testing is used to subject the elevator group controller to a randomly generated scenario (usually of passenger origin-destination pairs). The response of the group controller to a randomly generated scenario is recorded, and more scenarios are generated and added. The overall response (e.g., average of all responses) of the group control algorithm to the large number of scenarios represents an objective measure of its efficacy. The random scenario testing is first carried out under idealised or partially idealised conditions. Under the third component of the new paradigm, the conditions are gradually made more realistic and better reflective of reality. This third element is called the progressive introduction of reality.
Practical application : This paper presents to the designer of the elevator group controller a new paradigm for assessing the benchmark against which he/she is working. The designer can be confident that whatever up-peak group control algorithm he/she develops, it cannot exceed this upper benchmark. This has important practical applications in benchmarking the performance of up-peak group controllers. It can also be used by consultants and clients to mediate elevator group controller performance claims presented by elevator manufacturers.
The evaluation of the air quality in light shafts requires a specific study of its air renewal ability due to building shape, dimensions and other external conditions. This research has studied the capacity of light shafts to provide natural ventilation through the air change efficiency concept. A methodology based on the limitation of the computational urban domain is used to adapt the indoor air change efficiency index for outdoor environments. Numerical simulations were performed using CFD and a model that was experimentally validated.
The aim is to evaluate the effect of the centreline building width and light shaft dimensions in the air change quality within several wind climates. Results would provide a numerically proven tool for designers, summarised in some design-based strategies in order to select which one improves the air change quality.
The results indicate that the light shaft dimension perpendicular to the wind direction has a negligible effect on efficiency. For the range of wind velocities studied (0.75–9.00 m/s), the efficiency decreases at higher velocities, up to –7.41% with respect to the mean. For variations in the wind velocity and the centreline building width, a mean variation of ± 18.77% in the efficiency is obtained.
Practical applications: The present methodology defines a proceeding to numerically evaluate the air change efficiency in light shafts inside different dimensional cases of buildings within several urban wind conditions.
This research is a design and assessment of a bioclimatic house wall and roof to be constructed in Thailand’s housing market in order to provide information for potential builders as well as the peace of mind of the owner. The research found that a bioclimatic house with a double-layered solar chimney is appropriate for use in Thailand throughout the year. It lowers the average internal temperature of the house by approximately 1–2℃ when compared to the energy-saving material used in a normal building. Bioclimatic construction also creates natural ventilation, heat removal, and can reduce indoor temperature. It also comes with an easy-to-build design to facilitate construction and can save house energy consumption.
Practical application : This research provides helpful information of solar chimney wall and roof for both the owners and developers in adopting an energy-efficient house for sustainable energy conservation. A solar chimney of a bioclimatic house is a highly interesting alternative for saving energy in the long term. When properly promoted, it will help save a huge amount of energy throughout Thailand and tropical area, and serve to promote the cause of global environmental conservation into the future.
The existing methods of selecting design summer year weather data rely on the outdoor dry bulb temperature without considering solar radiation and wind which can impact on indoor thermal conditions. This research sets out to examine the existing outdoor warmth ranking metrics and proposes a new warmth ranking metric (solar air temperature), which takes into account not only dry bulb temperature but also solar and wind conditions. Parametric study was carried out using five typical UK dwelling models, by varying parameters associated with building design and operation, a large model population were generated to statistically determine how well the outdoor warmth ranking metrics correlate the predicted indoor warmth. The outdoor warmth ranking was made for the 20 years source weather data (1976–1995) in London and both CIBSE single temperature criterion and BS EN 15251 adaptive criteria were used to judge overheating in buildings. It is found that the predicted indoor warmth are mostly arbitrary in nature and none of the existing and newly proposed outdoor warmth ranking metrics can strictly correlate. The research also discovers the significant differences between the predicted overheating occurrence and severity in the warmth ranking of weather years.
Practical application : The parametric methods described in the paper will facility academics and industry researchers to assess design summer year weather generated by various methods. The research also provides guidance on assessing both overheating occurrence and severity in buildings to assist decision making.
This article proposes a calculation model for estimating the energy consumption and CO2 emissions resulting from hot water usage and for evaluating the potential for carbon reduction by using a water efficiency strategy. The model revealed a reciprocal relationship between hot water usage in daily life and energy consumption and carbon footprints. From 1990 to 2010 in Taiwan, hot water accounted for approximately 20%–30% of daily water consumption, and the use of hot water indirectly caused an average emission of 6.19 (kg-CO2/m3) and a 1.83% contribution to carbon emissions per capita. The potential influence of hot water usage on the issue of carbon reduction and the importance of strategies for saving water are thus highlighted in this study.
Practical application :The proposed calculation model clarified the relationship between hot water usage and carbon emissions. Through the investigation and simulation of domestic hot water usage, the carbon reduction potential of a hot water-savings strategy was validated. This study can make various organizations in both the public and private sectors aware of the importance of building a society based on the concept of water conservation, and various policy-making processes are anticipated to be initiated as a result. Efforts to save hot water could be consolidated to achieve synergy with carbon reduction policies and benefits to building service engineering.
The problem of improving the energy behaviour of existing buildings is a current topic of interest in scientific research. In recent years, Public Administrations have made an effort to introduce norms that help to reorient the tendency toward increasing energy consumption by buildings. To do so, manufacturers have developed numerous energy efficiency measures that have become widely extended. The main problem when selecting one or various measures is to identify the ones that will provide the best trade-off between services and implementation costs. This paper presents a study focused on implementing techniques for calculating the heating and cooling energy demand, along with genetic algorithm, to optimize the process of adjusting the building’s energy efficiency rating to a determined rating for existing building. The proposed optimization approach is applied to a real case to demonstrate its validity in a real-world situation.
Practical application: This paper presents an innovative method for the building energy retrofit process. By applying a simple genetic algorithm, the aim is to optimize the cost of intervening in an existing building by fixing the energy rating obtained at a given value. The practical potential of the method presented here is quite extensive, with its greatest exponent being its use by technicians who are unfamiliar with optimization processes. The application of this calculation methodology would simplify the study of projects in the phase of selecting energy-saving measures, given that there are currently many of them, with their independent characteristics, which makes the selection process a slow and ineffective task. In addition, the method’s intuitive interface and the fact that it is programmed in MS Excel make it an innovative method with great applicability in the field of building process optimization.
Low delta-T syndrome refers to the situation where the measured differential temperature of the overall terminal air-handling units is much lower than the normal value expected. It widely exists in the existing heating, ventilating, and air-conditioning systems and results in increased energy consumption. This paper presents a model-based method to evaluate the energy impact on the chilled water pumps due to the low delta-T syndrome in a complex chilled water system. When the low delta-T syndrome occurs, the chilled water pumps would deviate from their normal working conditions with increased power consumption. Models are developed to predict the reference benchmarks of the chilled water pump power based on the current cooling load, control rules, and preset set-points. The energy impact on the chilled water pumps can be determined by comparing the measured current pump power with the predicted benchmark. Support vector regression method is introduced for predicting the chilled water flow rate of the overall terminal units. Adaptive concept is employed to enhance the prediction accuracy of the overall pressure drop of the hydraulic water network under various working conditions. The proposed method is tested and validated in a dynamic simulation platform built based on a real complex heating, ventilating, and air-conditioning system. Results show that the proposed method can accurately evaluate the impact of the low delta-T syndrome on energy consumption of the chilled water pumps.
Practical application: Low delta-T syndrome widely exists in existing HVAC systems and results in increased energy consumption. This paper presents a model-based method for practical applications in assessing the energy impact on the chilled water pumps due to the low delta-T syndrome in a complex chilled water system. When the low delta-T syndrome occurs in a system, this method can be used to predict the reference benchmark of energy use of chilled water pumps based on the measured cooling load profiles, the control rules used, and the preset set-points. The energy impact can be determined by comparing the measured actual energy consumption with the predicted benchmark. The evaluation results could help the operators to conveniently monitor the energy performance of the chilled water distribution system as well as to judge whether or not taking measures to identify and correct the related faults that result in the low delta-T syndrome.
The paper discusses the possibilities of using passive greenhouse systems, such as glazed balconies, in an example residential building. The analyses were carried out for five localities in Poland, different in terms of external air temperature and insolation. Typical meteorological years were used as the source of climatic data needed in calculations. Two types of balcony’s casing were evaluated, with high and low thermal insulating properties. Demand for heating and cooling in a flat was determined with the use of dynamic computer simulations, and the outcomes were compared with the energy performance of a flat with an open balcony. Additionally, the number of hours with the internal operative temperature exceeding 26℃ was taken as a measure of overheating the apartment when natural airing by opening windows was included in simulations. The calculations showed diversification in the effectiveness of greenhouse systems resulting from climatic conditions, and allowed areas which are the most suitable for the passive use of solar radiation to be identified.
Practical application: Analyses present energy savings in a typical dwelling achieved thanks to glazed balconies, and allow to choose the most efficient type of balcony’s envelope taking into account the heating and cooling demand, and the risk of overheating. The results are diversified in respect of building’s location, showing the areas of Poland where the passive use of solar energy would be most beneficial. The calculations may become the basis for further economical evaluation of greenhouse systems effectiveness.
The energy consumed by domestic space heating systems represents a considerable share of the energy consumed in the UK. At the same time up to a quarter of English homes have inadequate controls on the central heating systems. Current modelling tools, and results from the limited field trials that have been carried out, are problematic due to the influence of the behaviour of occupants and variability of weather conditions. The Salford Energy House is a full-sized end terrace house built within a climate controlled laboratory. This allows a house of typical construction to be extensively analysed while completely disconnected from the unpredictability of weather conditions and human behaviour. This paper presents a series of tests carried out in the Salford Energy House into the effectiveness of installing room thermostats and thermostatic radiator valves. Savings of 40% in terms of energy consumption, cost and CO2 were achieved. The results should be regarded with caution in terms of their extent and application to real homes, but represent a significant contribution to the gap in current knowledge due to the ability to isolate the performance of homes from uncooperative variables, and a potential base for the development of more effective modelling tools.
Practical application: This research provides evidence to support installation and use of room thermostats and thermostatic radiator valves as an effective means of reducing domestic energy consumption and overheating.
Overheating is increasingly becoming a key issue for building design across the world. In the UK, better building fabric performance and warmer weather can increase the risk of overheating events in badly designed buildings. The impacts of these overheating events could be reduced by adapting building designs at an early design stage using building thermal models using appropriate weather data such as a design summer year. In this work, a method to determine probabilistic design summer years will be presented. These years take into account the return periods of actual events, are presented within a probabilistic framework and therefore include a description of the severity of the year at each location.
Practical application: Design summer years are designed to be used to optimise building performance in terms of thermal comfort at design stage. This paper demonstrates a method to create probabilistic design summer years which contain a range of overheating events which can be used to inform designers of the overheating risk to occupants. The proposed method is then used to generate new near extreme weather files for the UK.
The performance of hybrid solid desiccant–vapor compression air conditioning system is studied for the typical hot and humid climatic zone of North India (Roorkee). The system consists of a rotary desiccant dehumidifier coupled with heat recovery wheel and a conventional vapor compression air conditioning system. A FORTRAN program was developed to calculate different psychrometric properties like humidity ratio, dry-bulb temperature, wet-bulb temperature, relative humidity, specific heat, etc. at each state point of the system on the basis of ambient and desired inside room conditions, room cooling load, sensible heat factor, and required air flow rate. The overall system performance has been evaluated in terms of the coefficient of performance and the dehumidifier effectiveness. The influence of variation in ambient conditions on regeneration temperature of desiccants has also been discussed. The simulated results are validated using experimental measurements. The present system has ensured a reduction of 79.15% in processing air humidity ratio at an outlet of the desiccant dehumidifier as compared to the outdoor humidity ratio. The results show that the performance of the system is significantly affected by the variations in ambient temperature and humidity ratio.
Practical application : The proposed model of solid desiccant–VCR hybrid air conditioning system minimizes the energy usage in comfort cooling applications such as auditoriums, supermarket, hospitals, central library, offices, and lecture halls in hot and humid climate while maintaining an acceptable thermal comfort level and improving the performance. The proposed approach will give valuable insights to the researchers and building engineers to analyze the impacts of ambient conditions on the energy requirements and performance of solid desiccant cooling to ameliorate comfort, energy, and cost savings. Moreover, its potential contribution in environmental protection makes it more attractive at a time where depletion of energy resources and environmental degradation are of major concerns.
This paper reports results of a series of year-long simulations using TRNSYS computer code applied to Direct Solar Floor of a building made of local materials in Algeria. The Direct Solar Floor system was modeled and implemented using TRNSYS code. Then, energy saving was assessed through a mathematical approach calculating the heating load during winter. The internal climate was also evaluated by analyzing indoor temperatures and PMV along with PPD indices. Moreover, a parametric study was performed in order to evaluate the main characteristics that affect the performance of DSF with different construction materials used in Algeria.
Practical application: The use of renewable energies in Algeria is still not widespread despite its strategic geographical location. Because that the residential sector seems to be the biggest consumer of energy and it widely contributes to greenhouse gases (GHG) emissions, the technique of heating by Direct Solar Floor (DSF) could be a very interesting solution to reduce both of energy consumption and GHG emissions.
The DSF is still a relatively novel heating technology in Algeria. This paper describes the use of this technique in some typical Algerian constructions: old traditional buildings which are rarely used and modern buildings which are very common. Such as presented in this article, the use of local materials contribute to improving DSF performance. The parametric study presented in the paper offers designers decision-making tools to size appropriately a DSF heating system according to the construction materials used.
The article describes from an architectonical point of view the design, assembly, and energy behavior of a prototype for air-conditioning in residential buildings using Peltier cells, which means the application in the field of construction of a technology used in very specific areas. The new system has been designed as an independent, prefabricated, modular construction element that must fit perfectly between the structural floors and is easily adapted to the demands of different buildings. The thermoelectric cooling heating unit is designed to offer a high level of comfort to those living in the building. The only mechanical elements are the dissipation heat fans placed on the outside of the prototype, and heat sinks to transfer the heat from the power elements, reducing the possibilities of failure. The result of all these ideas is the construction of a prefabricated module, consisting of a simplified inhabited housing unit with a thermoelectric installation serving the module, which has obtained a national patent. The results of the thermal and electric behavior demonstrate that the system does not work as well as had been expected; nevertheless, the system has a high potential for its use in buildings associated with photovoltaic.
Practical application : The system opens new ways to the air-conditioning without using the traditional concepts of primary and secondary loop, because the system is highly independent. Their applications could be in building refurbishment where other systems involving the use of water or air are complicated to implement, in spaces where security and resilience are crucial factors (such as surgeries or computer server rooms), or those situations with extreme maximum and minimum temperatures or irregular electrical supply, as those could exist when the army must intervene or an humanitarian disaster occurs.
There are over 70 low energy and carbon standards in use around the world. None of these standards have been designed by the clients who pay for and occupy the buildings in question. In this work, the client was asked to define the building code for the construction of a new 2800 m2 building via a structured survey. The resulting zero-energy standard simply required the building to incur no energy utility bill. One year of monitoring of the completed building was used to see if the standard had been met. The result of this work is a new way of thinking about environmental building standards that solves many of the issues of obtaining and maintaining buy-in from the client.
Practical application: This is the first time that the client has played a key role in the definition of a low-energy building standard. Measured energy consumption and renewable energy generation data are presented and demonstrate that the zero-energy criteria were successfully met. This work is important as it shows that the client can have a meaningful input into the design of an environmental standard. The paper should be of interest to architects, engineers, building energy researchers and those interested in methods that can be used to reduce the energy demand of buildings.
A noble integration of a cascade refrigeration system with a two-stage compression chiller is proposed. The compression and the absorption systems have a cascade inter-cooler/evaporator, and the compression system has two compressors working in series. The compressors can be either reciprocating or screw type. This system runs by a driving unit which can be a micro-turbine or a solid oxide fuel cell. The system components are modeled and analyzed through the energy and exergy approaches. The performance parameters of the systems and the second law efficiency are calculated in different operating conditions. The results show that the maximum irreversibilities happen in the generator and the first-stage compressor, and the total destruction is higher when a micro-gas turbine is used as the prime mover. It appears that by using reciprocating compressors, energy and exergy are consumed up to 260% and 188% more efficiently in the proposed system compared to a traditional single-stage compression refrigeration system. The two latter parameters would be 53.7% and 29.2% in case of using screw compressors.
Practical applications: So much of our lives rely on refrigeration, from the food that we eat to the transportation and processing of vital resources. Industrial refrigeration systems such as gas compression, oil and gas processing, petrochemicals, power generation, carbon capture and food processing and storage are dependent on low-temperature refrigeration systems. Multi-stage refrigeration cycle is a conventional approach to provide low temperature for industrial processes. The proposed cascade system can reduce the energy consumption of a two-stage refrigeration system, using the waste heat from an industrial process. The first and second law analysis of the proposed system approves the upgrade in energy and exergy efficiencies of this system.
The effective design of an energy efficient heating, ventilation and air conditioning system is reliant on multiple components. Among others, the air-handling unit cooling coil and its ability to perform efficiently directly influences heating, ventilation and air conditioning system performance. This paper investigates the energy and thermal performance of a water-cooled central cooling plant when combined with a direct evaporative cooling system located between the cooling tower and cooling coil of the air-handling unit. The evaporative cooler uses the water made by cooling tower to reduce the temperature of the 100% ambient air. The cooled air then passes through the cooling coil. This paper will demonstrate a series of mathematical models of the system components and validate them against experimental results. For this purpose, the central cooling plant is extensively equipped with a number of sensors and instrumentation devices for experimentation and data collection. The influence of the evaporative cooler on the energy saving potential and thermal comfort of the central cooling plant is evaluated. The advantages of this proposed hybrid system rests with the fact that the refrigeration effect of the chiller’s evaporator is decreased, which causes reduction of compressor power consumption. Results show that the hybrid system can provide average monthly energy savings between 11% and 24%, while enhancing the comfort level inside the building.
Practical application : With traditional heating, ventilation and air conditioning systems contributing to 40% of a building’s overall energy consumption, the public’s increasing reliance on them as a necessity rather than a luxury is an issue in urgent need of attention. This together with a growing demand for cost-effective infrastructure and appliances has necessitated new installations and major retrofits in occupied buildings to achieve energy efficiency and environmental sustainability. The aim of this paper is to present a new integrated heating, ventilation and air conditioning system to meet these requirements without compromising comfort and indoor air quality.
Defrosting is an important controlled event of variable refrigerant flow air conditioning system (VRF AC). The whole course includes defrosting preparation phase, defrosting execution phase, defrosting end preparation phase and pump-down residual running phase. The defrosting control function can make a great influence on the performance of variable refrigerant flow air conditioning system, whose elements are composed of a certain controlled event, controlled components, executed conditions, controlled time, controlled courses and control logic. A sequence diagram is adopted to express the defrosting dynamic process and the control models of execution conditions on defrosting arrival, defrosting end and pump-down residual running end have been built. Thus, the defrosting control function has been formed based on the model and sequence diagram. The defrosting experiments demonstrate that the built model and sequence diagram can scientifically and accurately express the defrosting control function.
Practical application: Defrosting is an important controlled event of variable refrigerant flow air conditioning system. It is difficult to describe the complex controlled course, which is composed of defrosting preparation phase, defrosting execution phase, defrosting end preparation phase and pump-down residual running phase. A sequence diagram can be adopted to express the defrosting dynamic process and the control models of executed conditions on defrosting arrival, defrosting end and pump-down residual running end have been built. Thus, the defrosting control function has been formed based on model and sequence diagram.
The merit of applying variable-speed ground-source heat pumps (VSGSHPs) to displacement ventilation (DV) systems was investigated for use in offices in Hong Kong. To improve the dehumidification capacity of the DV systems, a sensible heat recovery wheel was added between the mixed and supply air streams with a heat recovery effectiveness of 0.4. By maintaining the peak fluid temperature leaving the ground heat exchanger borefield after one year to be the same, the required borehole depth and the total energy consumption of the modified DV system were reduced by 16.8% and 19.4%, respectively, as compared to a conventional mixing ventilation system which employed a constant-speed ground-source heat pump. This enhanced the economic feasibility of applying ground-source heat pumps to sub-tropical regions.
Practical application: The high initial cost of ground-source heat pump systems is the main obstacle to their wide acceptance in actual practice, particularly for application to sub-tropical regions where the air-conditioning demand is cooling-dominated. The present study demonstrates a design strategy in which both the initial and running cost of the ground-source heat pump systems can be reduced, thus enhancing the economic feasibility of the systems.
Heat transfers into refrigerated cabinets from their surroundings. Currently, this heat transfer is ignored in building design compliance protocols (National Calculation Methodology), and a heat gain to the zone is included in modelling the retail floor, to represent the energy use of the refrigeration system, although this is normally outside of this zone. Previous work has established that a store designed for energy reduction with the heat transfers to refrigerated cabinets from the surroundings included in the modelling could have at least 20–35% lower energy demand (and CO2 emissions) than a store modelled and ‘optimised’ on the National Calculation Methodology basis. This paper therefore offers an appropriate algorithm for ‘negative gains’ relating to refrigerated cabinet heat transfers for use in design and compliance modelling of supermarket buildings.
Practical application: The algorithm offered, when incorporated into design modelling, will enable significantly improved identification of the sensitivity of the thermal balance of the supermarket building to variation of building envelope parameters, and thereby enable significantly improved energy savings to be realised.
Improving energy efficiency and temperature control in hot water heating (HWH) systems are important considerations. The more challenging problem is to maintain good set point control under failure conditions. In this paper, model-based fault detection and diagnosis (FDD) and fault tolerant control (FTC) strategies were designed and simulated for a high-rise building HWH system. An overall system dynamic model with multiple control loops was developed. In the FDD methodology, fuzzy inference systems were employed to isolate the faults and evaluate the fault level. In the FTC strategies, error correcting function was defined consisting of set points, measurement and FDD information. A supply water temperature sensor fault and a multi-fault scenario consisting of heater efficiency fault combined with a partially blocked control valve fault were studied. Simulation runs showed that the developed FDD strategies isolated the faults and the designed FTC strategies were able to improve the system performance.
Practical application: The performance of control systems is frequently degraded by the faulty sensors and actuators in hot water heating systems. By implementing the designed fault tolerant control strategies the hot water heating system can be operated to achieve higher energy savings both under fault free and faulty conditions.
It is important to limit dwelling infiltration to reduce energy demand and help meet national climate change commitments while concurrently providing sufficient ventilation to deliver adequate indoor air quality. DOMVENT3D is a model of infiltration and exfiltration that assumes a linear pressure distribution over any number of uniformly porous facades and integrates the airflow rate in the vertical plane to predict the theoretically correct airflow rate through them. DOMVENT3D is a new development of an existing two-dimensional model of infiltration that provides more opportunities for investigating a greater number of dwellings than was previously possible. Initial testing suggests that DOMVENT3D is mathematically robust and is suitable for modelling a wide variety of dwelling types and geometries to assist engineers and policy makers.
Practical application: The modern building services engineer may be required to model airflow networks in a building to balance the conflicting needs of energy consumption reduction and occupant health. Limiting exfiltration is one method of reducing heat losses from a building and so there is a need to model it accurately. This article presents a new model of infiltration and exfiltration through a uniformly porous facade that can be incorporated within advanced complex airflow network tools or applied using a simple spreadsheet.
Seasonal input–output efficiencies of two heating plants with condensing boilers in cold climate institutional buildings (3300 m2 school and 12,000 m2 university building) were evaluated. Plant efficiency remained about the same or declined with load, contrary to typical lab boiler ratings, which show efficiency increasing at lower loads. These results occurred when the boilers were operated with return water temperatures largely in the condensing range. Heating plant load was often 25% or less of the rated load of a single boiler, resulting in heating plant input–output efficiencies well below rated boiler efficiencies.
Practical application : In-situ boiler plant input–output efficiencies can differ widely from manufacturer's boiler efficiency curves. For applications such as simulation for energy-efficient design, effective decision-making depends on accurately estimating real-world performance.
It has been shown by many researchers that over a long term there has been a slow but steady rise of ambient temperature within the Indian sub-continent. Due to an increased economic prosperity there has been an accompanied increase in the urban heat island effect. Furthermore, urbanisation of large cities in India has also led to higher population densities. The above factors had the combined effect of a significant increase of cooling load of buildings. The high density of dwellings and other building construction has resulted in shading of walls. However, the flat roof spaces are exposed to an uninterrupted solar radiation regime and this in turn leads to generation of high sol-air temperatures which cause higher cooling loads. Presently, it has been argued that roof spaces are one of the major contributors to building cooling load. In this article, the reasons behind the phenomenal rise in the installation of air-conditioners in India are reviewed. The dual role of roof-top PV systems in electricity generation and reduction of building cooling load due to the shading they provide is then investigated. For this purpose, the CIBSE method to obtain sol-air temperature with solar radiation and outdoor ambient temperature has been used. Sol-air temperature for five key Indian locations (Delhi, Bhopal, Ahmedabad, Bhubaneswar and Chennai), based on the recently presented data by the NREL-India Meteorological Department consortium, were then obtained. A computer simulation routine was presently developed for solving the classical transient heat conduction problem with hourly sol-air temperature data and roof construction details provided to the routine. This program was executed to obtain the cooling load profile for each of the five Indian locations for the respective design day.
Practical application : The present work reviews the reasons behind the phenomenal rise in the installation of air-conditioners in India. The dual role of roof-top PV systems in electricity generation and reduction of building cooling load due to the shading they provide has been investigated. The computer simulation demonstrated that the energy required for roof-induced cooling load decreased between 73% and 90% after installation of the PV system. The method used in this work has the advantage that it enables the user to obtain cooling load estimates using a general transient heat conduction approach. Moreover, all software was developed within MS-Excel environment, this is also an additional advantage as the cost associated with purchase and training of proprietary building energy software can be prohibitive for many consultants who are based in developing countries.
Energy-saving elevator dispatching has been recognized as a challenging issue in building transportation, and we develop a novel energy-saving dispatching strategy for regenerative group-elevator system. Group-elevator dispatching is a typical combinatorial optimization problem, and three keys of the dispatching optimization are optimization method, objective, and model. The three keys of energy-saving-oriented elevator dispatching are studied in this paper. First, robust optimization method is introduced to handle dispatching optimization under uncertain elevator traffic flows; uncertain flows influence energy-saving dispatching seriously. Second, dispatching energy-objective function for regenerative group-elevator system is derived both schedule energy for four traffic patterns (up-peak, down-peak, up/down-mixed, and night) and return energy for two peak patterns (up-peak and down-peak) are considered. Third, four robust optimization-dispatching models for four traffic patterns are built, and optimization objectives of four models are minimizing the energy-objective function. Moreover, because we cannot solve robust optimization models with uncertain parameters directly, model counterpart transformation is studied. Finally, we solve the four transformed models by Linear Interactive and General Optimizer software and obtain robust optimization-dispatching solutions. In practice, four energy-saving-dispatching robust optimization models are switched according to real-time traffic patterns, and elevators are dispatched based on the dispatching solutions. We reduce elevator system-energy consumption effectively and keep average waiting time of the passengers acceptable under multi-traffic patterns. Simulation results demonstrate the validity of our strategy.
Practical application: Group-elevator system spends much unnecessary energy because of the uncertainty of elevator passenger-traffic flows. This paper develops an energy-saving elevator-dispatching optimization strategy, which is immune to the uncertainty of four typical traffic flows. In practice, we update the group-elevator controller by our algorithm to realize energy-saving dispatching of regenerative group-elevator system under multi-traffic patterns.
Legislation in the Netherlands requires routine analysis of drinking water samples for cultivable Legionella species from high-priority installations. A field study was conducted to investigate the presence of Legionella species in thermostatic shower mixer taps. Water samples and the interior of ten thermostatic shower mixer taps were investigated for cultivable Legionella species. In seven cases, Legionella species was found in at least one of the samples. In four cases, Legionella species was detected in the biofilm on the thermostatic shower mixer taps interior, with the highest values on rubber parts, and in five cases in the cold supply water. These results show that thermostatic shower mixer taps can play a role in exceeding the threshold limit for cultivable Legionella species, but the cold supply water can also be responsible.
Practical implications: This study showed that contamination of thermostatic shower mixer taps (TSMTs) with Legionella spp. was frequently observed in combination with contamination of the water system. Consequently, a combined focus is necessary to prevent the proliferation of cultivable Legionella spp. in TSMTs. In addition, the results also demonstrated that biofilms on rubbers inside the TSMT had high numbers of Legionella spp., probably because rubber contains relatively high concentrations of biodegradable substrates. Therefore, improvement of the rubber materials is necessary to reduce the proliferation of cultivable Legionella spp. in TSMTs.
Increasing building tightness is one of the measures taken by the construction industry to reduce energy losses, but leading to unhealthy environments. Efficient ventilation strategies with low energy consumption are necessary in order to design and improve the existing forced ventilation systems. This paper assesses the potential use of different strategies, independently from the architectural design, to achieve efficient ventilation. To this end, the airflow pattern and the age of air have been assessed in an en suite bedroom within a Spanish house with the use of computational fluid dynamics predictions. The computational fluid dynamics model predictions were validated by the comparison against experimental measurements, with good agreement. An alternative ventilation strategy is proposed, not affecting the architectural design of the room. Statistical analysis is used to assess and compare the results obtained for the different cases simulated. Results show that although the room has a forced ventilation system, air stagnates and ventilation are not homogeneous. Statistical analysis shows that this strategy produces a significant impact on indoor air quality, particularly in bedroom areas where air tends to stagnate.
Practical application: The Spanish Building Code provides a minimum level of air quality within the buildings although it does not ensure an efficient design of the ventilation system, being necessary the use of guidelines or other recommendations to advise the designers in order to achieve efficient ventilation designs. Implementation of strategies independent from the architectural design, as studied in this work, can improve the indoor air quality and therefore reduce the global building energy consumption. In addition, these solutions are recommended for construction works requiring quick-easy implementation without disturbing the inhabitants of a house and allowing the normal use of the building during the refurbishment works.
It is always a challenge to develop appropriate mathematical model for a direct expansion (DX) air conditioning (A/C) system, whose operational parameters are highly coupled and behave non-linearly. Different modeling approaches have their own merits. However, none of the currently available modeling approaches can solely satisfy the requirement, in terms of accuracy and sensitivity, for simultaneous control of air temperature and humidity using a DX A/C system, without any inadequacies. On the other hand, when developing a model for the purpose of controller development rather than investigating complete system characteristics, the focus would be on several key components, and the modeling for other components that are relatively less important may be simplified. Therefore, it is possible to utilize different modeling approaches for different physical processes to develop a novel control-oriented hybrid model, named as semi-physical model (SPM). In this paper, rationales for using different modeling approaches for different physical processes of a DX A/C system are firstly discussed, followed by the development and validation of the SPM. The development of a SPM-based controller for the simultaneous control of air temperature and humidity is also briefly introduced, and its control perform acts as additional evidence for validating the SPM.
Practical application: This paper presents a hybrid modeling method, which combines the complementary merits of various modeling approaches and avoid the inadequacies of them based on the analysis of the requirement of controller development. Such a new control-oriented hybrid modeling method can be applied to not only simultaneous temperature and humidity control using a variable-speed DX A/C system but also other control applications where control loops are coupled and system operational characteristics are complicated.
Monthly-averaged daily global irradiation data are now easily available from NASA website. Using established models it is then possible to decompose the daily to averaged-hourly global irradiation. The missing link so far has been hourly averaged diffuse irradiation. In this article data was pooled from 10 UK locations to obtain a regression model to complete the above missing link. It was presently shown that the averaged-data regressions are distinctly different from previously available hour-by-hour regressions.
Practical application : The present work has explored a correlation between averaged-hourly diffuse and global irradiation using the diffuse ratio–clearness index envelope. Results show that a strong regression relationship is thus obtainable. The present work has therefore the potential for other similar research that may be followed up in a likewise manner.
Renewable energy plays a crucial role in replacing major part of fossil fuels to generate sustainable, inexhaustible, clean, and safe energy. In Hong Kong, solar energy has been identified suitable for wide-scale applications. Photovoltaic (PV) and solar water heating (SWH) facilities are the two promising solar-based conversion technologies. Electricity and hot water generations via solar energy means fossil fuel saved together with the likely pollutants and greenhouse gases reductions. However, there are a number of barriers including high initial cost and large installation space required. This paper studies the cost, energy, and environmental issues when PV and SWH systems are widely used in Hong Kong. The energy expenditures in the forms of electricity, gas, and hot water, and the global solar radiation in Hong Kong were analyzed. The total required land areas, the financial implications, and the environmental benefits for such solar energy applications were estimated and reported.
Practical application: Solar energy plays an important role in replacing fossil fuels to generate electricity without emitting pollutants and requiring no fuel. This paper analyzes the energy, financial, and environmental aspects for solar thermal and solar electric installations. The findings in this study provide the information when active solar energy systems are widely applied in Hong Kong.
Nowadays, the most applied insulation material in the building sector is the expanded polystyrene. Different types of expanded polystyrene are used but more widely used is the graphite added type. Our research focuses on the analysis of heat conductivity and sorption properties of expanded polystyrene as these two are the most important physical properties from energy saving point of view. In this paper, the variation of heat transfer coefficient of an insulated wall is analysed in function of humidity content of insulation material. Brick and concrete walls with 0.4 m thickness were chosen for substrate and 0.1 m expanded polystyrene (30, 100, 150, 200 and the so-called grey expanded polystyrene) materials were applied as insulating layers. The investigations of sorption behaviour of the materials are important from the point of view of fundamental research and building technology as well. Sorption data taken from our previous measurements results were used for predicting the change of the overall heat transfer coefficients of different wall structures constituted this way.
Practical application: The present technical note is based on our previous measurement results. Water can cause undesirable changes in the building structures and introduced in this article. During the fixing procedure of the additional insulating of a given building bad weather conditions (high relative humidity and/or low external temperature) can dominate. These phenomena can be imagined for building new houses. By the ‘in-building’ of the moisture into the wall structure, numerous and measurable change can happen in the U-value of the building envelope. The presented changes are estimations only, but can be used and can also help for planning and executing the insulating process.
Since radiant floor heating systems utilise part of the building as a system for controlling the indoor environment, the integrated analysis considering the interaction between the building and the system needs to be conducted for the performance evaluation. Integrated simulation can be applied for this purpose; however, it is somewhat difficult to evaluate the impact of the system hardware such as hydronic circuits and heat sources due to the lack of modeling information. Although the experimental methods can guarantee the most reliable results, they have a limitation on the repetitive comparison due to the restriction of time, space and cost. For this reason, this study presents an emulation method that can mitigate the disadvantage of the simulation as well as experimental methods, especially for the performance evaluation of radiant floor heating systems. To achieve this, the factors to be considered in radiant floor heating systems were examined by reviewing the previous studies on the emulation. This study suggested an emulation method that can physically represent pressure loss in the hydronic circuits and heat output from the floor structure, which are distinguishing features of radiant floor heating systems. With the developed emulation method, this study showed that the control performance and energy consumption of a radiant floor heating system can be investigated.
Practical application: This study presents an emulation method to evaluate the energy consumption and control performance of radiant floor heating systems. The proposed emulation method will be able to supplement a pure simulation and to contribute to the development of an evaluation method considering the impact of system hardware on the overall performance of radiant floor heating systems. Therefore, it is expected that the results will be helpful to researchers for indoor environment, heating, ventilating and air conditioning engineers, system manufacturers and those who want to analyse the energy performance of radiant floor heating systems.
Building more air-tight dwellings is having a deleterious impact on indoor air quality. In a range of recently completed dwellings CO2 concentrations were measured in occupied bedrooms at unacceptable concentrations (occupied mean peak of 2317 ppm and a time weighted average of 1834 ppm, range 480–4800 ppm). Such high levels confirm that air-tight dwellings with only trickle ventilators as the ‘planned’ ventilation strategy do not meet the standards demanded by the Building Regulations. Reducing ventilation rates to improve energy efficiency and lower carbon emissions, without providing a planned and effective ventilation strategy is likely to result in a more toxic and hazardous indoor environment, with concurrent and significant negative long-term and insidious impacts on public health. Furthermore, the methodology underpinning the current regulations cannot be considered as creditable. While the complexity around numerical modeling often leads to conclusions based upon simplistic and unrealistic assumptions around all doors in a dwelling being open and trickle ventilators being unobstructed, this paper demonstrates that in ‘real life’ situations, this is not the case and could lead to significant risks of under ventilation. This is particularly the case when standards and guidance are based upon theoretically modeled scenarios that are not representative of real-life operation. The consequences of this are important in terms of the likely negative impacts on occupant health.
This paper presents an approach towards enhanced building-integrated wind harnessing. It uses building forms and profiles to trigger continuous air entrainment to power turbines. Computational fluid dynamics is used for evaluating, testing, and optimizing proposed designs. Wind separation around buildings is modeled alongside an investigation into the parameters of a wing-profile to accelerate wind. Computational fluid dynamics provides a good tool for modeling, designing, and optimizing aerofoil shapes. The main parameters affecting the wing’s wind harnessing capabilities are the distance between the wing and the building and the angle of attack of the wing. The aerofoil can magnify wind velocity by a factor ranging from 0.53 to 3.5; that is, from just below Betz limit to over six times the limit, depending on incident velocities.
Practical applications: The approach presented in this paper can be implemented directly into optimization of new designs of buildings to integrate wind energy harnessing. Furthermore, new proposed wing shapes or profiles can be investigated by the same procedure presented in this study. Computational fluid dynamics investigations to building-mounted wind technologies, such as the ones presented here, are becoming increasingly adopted in the design process in practice, in university courses and future research.
Air source absorption heat pump is promising in energy saving and emission reduction of heating and domestic hot water, but performs badly or even cannot work in cold climate. The ammonia/absorbent air source absorption heat pump with low-pressure boosting is proposed to solve the problem. The hybrid air source absorption heat pump + compressor system is modeled and the compression ratio is optimized to obtain maximum primary energy efficiency. The integrated system is simulated with air temperature ranging from –30°C to 10°C and hot water temperature from 30°C to 60°C. Comparative simulations on three working fluids reveal that NH3–LiNO3 system has the lowest compression ratio and the highest primary energy efficiency value. By pressure boosting, the air source absorption heat pump can operate under air temperatures as low as –30°C. Primary energy efficiency of the hybrid system is about 15–50% higher than that of coal boiler, showing great potential for heat supply in cold regions.
Practical application: Heating and domestic hot water consumes a large amount of energy every year. Air source absorption heat pump can be a potential alternative to the traditional boiler systems in the point view of primary energy efficiency. However, air source absorption heat pump performs badly or cannot work when the air temperature is low. This paper presents a hybrid air source absorption heat pump with pressure boosting to improve the performance of the air source absorption heat pump heating system, making it operate under lower outdoor air temperatures with higher primary energy efficiency. The novel heat supply system is expected to make contributions to building energy saving as well as pollution reduction.
Lift traffic design can employ calculation or simulation methods. Calculation can be split into main categories: analytical equation-based methods and numerical methods. Simulation can be split into discrete event simulation and time-slice simulation. These methods vary in the level of computational complexity, as well as their ability to arrive at a value for the required performance parameters with acceptable accuracy and under the general case. Moreover, the repeatability of the results is an important consideration, as well as the simplicity and calculation time of the method used. This technical note provides a general overview of each of the four methods. It also discusses the suitable areas of application of each of the methods, showing the strengths and weaknesses of each of the four methods. This technical note concludes by outlining the current hybrid method used by designers in lift traffic design, whereby one of the calculation methods is used to find a starting arrangement and then the design is fine tuned using one of the simulation methods (e.g. changing speed, capacity of the lifts as well as the group control algorithm) in order to achieve the required average passenger waiting time and average passenger transit time.
Practical application: This technical note provides a blueprint to lift traffic designers for the lift traffic design process. It emphasises the fact that calculation and simulation are not mutually exclusive methodologies, and shows how they complement each other, where the former provides a starting design and the latter allows the designer to fine tune the lift traffic design.
The performances of combined cooling, heating and power (CCHP) system are greatly dependent on its design, operation strategy and thermal and electric demands. This paper illustrates how the use of a genetic algorithm can provide speedy optimization, by applying it to two styles of buildings operated in different operation strategies. The primary energy consumptions of CCHP system following electric demand management (EDM) and thermal demand management (TDM) are firstly analyzed respectively. Then, sixteen hypothetical buildings are constructed to represent various energy demands. Primary energy saving (PES), annual total cost saving (ATCS), and CO2 emission reduction (CO2ER), are weighted to evaluate the integrated performances of CCHP system in comparison to separation production system. Finally, the optimized CCHP system for sixteen scenarios using GA are compared.
Practical application: This paper provides an optimization design method for CCHP system. The performance analysis of CCHP systems running different operation modes for different buildings is believed by the authors to contribute to a significant guide for the fundamental design of CCHP systems. Although sensitivity to a number of other important design considerations such equipment performance, possible future changes in operating conditions, changes to the price or carbon intensity of grid-supplied energy etc are not addressed, the conclusions present a simple and effective direction and the proposed optimization algorithm and the evaluation method for CCHP system can be extended to other buildings.
This paper concerns the impacts of future climate change under two forcing scenarios on energy demand of commercial building and residential buildings with different energy-saving levels in Tianjin. Heating load of commercial building will decrease under the two scenarios in the next 90 years but increase of cooling load is found. All residential buildings will decrease heating load in the future 90 years. In particular, the decreasing rate of energy demand during 2011–2100 by the residential building slows down from the first- to the third-stage energy-saving levels. Additionally, the difference in energy demand between the two scenarios becomes smaller as the energy-saving level increases. These suggest that higher energy-saving levels are beneficial for decreasing not only energy consumption but also its sensitivity to climate change.
Practical application: Climate change in the future causes the large and significant increase in cooling energy demand but decrease in heating energy demand. This would be helpful for the adjustment of energy use strategy by government. Also, the possible changes in future energy demands for heating and cooling will be of interest to energy providers. The responses of heating energy demand to the future climate change show large difference among the residential buildings with different energy-saving levels. This will provide useful information for policy makers and building industry managers on how to make appropriate measures keep occupants comfort and reduce energy use.
Balconies are green features commonly used in residential buildings to improve natural ventilation and air quality. Small vents, if mounted with an acoustic silencer, can reduce noise penetration while still allowing natural ventilation to occur. In this study, the computational fluid dynamics method is used to investigate numerically the effect of balconies with small upper and lower vents on the ventilation and air quality of the 4th, 5th and 6th floors of a 10-storey building. The results show that balconies can significantly increase the natural ventilation on these floors and generally have a more positive effect on the improvement of natural ventilation and the reduction in pollutant concentration on the floor on which they are located rather than on the levels above or below.
Practical application: This study will help designers and engineers understand more about the effect of balconies and lower and upper vents on natural ventilation and indoor air quality in buildings. This study will also help them to incorporate with confidence the design of balconies with lower and upper vents.
In the past, the building energy consumption was surveyed without distinction of air-conditioning system types, which caused large dispersal of the energy consumption of the same building type. To study energy consumption of office buildings using air-source heat pump, six office buildings using air-source heat pump in Shanghai were investigated through energy audit and field test. The energy use intensity (EUI) per annum ranged from 102 to 139 kWh/m2, with an average value of 126 kWh/m2. The EUI range of office buildings using air-source heat pump is much smaller than the EUI of office buildings according to the literature. Based on field test of the air-conditioning (A/C) system, it was found that the present main problem of A/C system included insufficient refrigeration capacity of A/C system, low A/C system energy efficiency, and small cold water temperature difference. Countermeasures were brought forward to solve the problems, including retrofitting part of the present air-source heat pumps to water-cooled cold water air-conditioners, retrofitting present air-source heat pumps into new air-source heat pumps, and pump variable frequency renovation. The A/C load is estimated by Bin method. According to the case study in this paper, the pay back period are about two years for the first measure, five to seven years for the second measure, and 0.65–2 years for the third measure.
Practical application: Generally, the energy consumption survey gives a wide range of data. To some extent, it is caused by the survey method which does not take the air-conditioning type into consideration. The work stresses on the energy consumption of office buildings using air-source heat pump. The result showed that the energy consumption was in a relatively small range, which will be more meaningful to industry. Energy saving measures concerning air-conditioning system is studied on the basis of the survey.
Recognizing high-rise building water-use maneuver should be helpful for developing some practical strategies when indoor room space safety becomes a crucial feature in the building operation. This paper presents a data-processing approach for exploring the water-use maneuver of high-rise building. This approach combines the empirical mode decomposition and statistical analysis to process the mezzanine-floor air-pressure data measured in the drainage stack system of Li Ka-Shing building at PolyU of Hong Kong on 28th of April of 2008. Because the mezzanine-floor air-pressure signals in the building drainage system are recorded within about 10 hours with a recording rate of one signal per second, data re-sampling is obviously needed. Otherwise, the direct application of empirical mode decomposition should be unavailable because the mezzanine-floor air-pressure data are too massive. Statistical analysis is further encompassed after the empirical mode decomposition to seek the influences of re-sampling time interval and the empirical mode decomposition index so that the building water-use maneuver can be understood in detail.
Practical application: From the viewpoint of Building Services Engineering, any occupied space should be safeguarded, because the depletions of the trap seals and the bathroom floor drain traps can result in cross-contamination via the drainage system. This suggests that it is crucial to investigate building water-use maneuver when indoor room space safety becomes urgent. To explore the water-use maneuver, an indirect way is by analyzing the mezzanine-floor air-pressure in the drainage stack system in terms of an appropriate approach. Since the mezzanine-floor air-pressure in the drainage stack system of an 18-floor building, i.e. Li Ka-Shing building at PolyU of Hong Kong has been recorded it can be used to propose the water-use maneuver approach which is helpful for developing some practical strategies for indoor room space safety when the safety should be carefully and urgently faced.
Siphonic roof drainage systems are an efficient method of removing rainwater rapidly from roofs. Siphonic roof drainage systems are designed to run full-bore, resulting in sub-atmospheric system pressures, higher driving heads and higher system flow velocities. Hence, siphonic roof drainage systems normally require far fewer downpipes, and the depressurised conditions also mean that much of the collection pipework can be routed at high level, thus reducing the extent of any underground pipework. But, they work properly at only one roof run-off rate and therefore suffer from sizing and operational problems that limit their performance. Climate change is creating situations where normal ranges of rainfall intensity are being frequently exceeded, and this may have an impact on the performance of siphonic roof drainage systems. A multiple parallel pipe siphonic roof drainage system appears to offer benefits and avoids sizing problems associated with current siphonic roof drainage systems. A movable cap covering the inlet to a small bank of parallel pipes has the potential to avoid noise associated with making and breaking siphonic action through flow modulation. Laboratory scale tests demonstrate the basic feasibility of the multiple parallel pipe system and indicate that handover of flow between pipes occurs smoothly and that the flow modulation cap functions reliably. This technology includes moving parts and smaller diameters (19 mm ID) than are currently accepted (32 mm ID) in the British Standards and product development will be required.
Practical application: Original research detailing an innovative development of a multi-pipe siphonic roof drainage system. This provides a wide design flow rate range and flow modulation caps reduce noise significantly by avoiding priming failure. Potentially extends the technique to a smaller building size than with current siphonic systems and offers climate change resilience potential.
This article presents the effect of envelope measures on thermal environmental conditions of a naturally ventilated building block in composite climate of India. Envelope measures such as roof U-value, wall U-value, glass U-value and glass solar heat gain coefficient, roof reflectance and two combinations of these measures (total seven cases) are analysed as recommended by National Energy Conservation Building Code-India (ECBC) through prescriptive route. Subject building is modelled and simulated using dynamic thermal simulation tool. Two approaches of thermal comfort have been used in this study such as heat balance model based on laboratory study and adaptive model of thermal comfort based on field findings. Thermal environmental conditions are evaluated based on operative temperature with and without considering the effect of thermal adaptation. This study found that comfortable temperature varies from 20.3°C to 31.5°C based on calculation of comfortable temperature through comfort temperature equation during winter to summer season in warm climatic conditions. This study concludes that envelope with ECBC specifications offer 60% hours under comfort state which were not comfortable with conventional practiced envelope specifications of India. The same methodology is also used to investigate the effect of ECBC envelope specifications in other climatic conditions such as hot and dry, and warm and humid climate of India.
Practical applications: The thermal performance of building envelope varies from climate to climate therefore care should be taken to choose particular envelope measure. This study aims to improve comfort conditions in naturally ventilated building block considering building code with/without thermal adaptation. This research would be helpful to architects, engineers and building constructors to choose the most effective or climate responsive envelope option for better thermal environment quality of the proposed building design. Use of thermal simulation tool is also recommended to examine the effect of envelope options on thermal comfort.
To reduce work in assessing alternative system structures in low-energy design, a Branch and Bound method is proposed. The bound is based on exploiting the thermodynamic constraint of exergy destruction along a heat flow path. A novel derivation of exergy in a flow system is provided and used to show its fundamental relationship with temperature and primary energy. The method is applied to two simple systems.
Practical application: In novel low-energy design, there can be many structural solutions that meet the client brief, especially at early stages in design, before full simulation/optimisation can be efficiently applied. The technique presented offers an application of the Branch and Bound algorithm that can be implemented on a spread sheet and which usually reduces the number of full structural solutions that have to be produced. It relies on working in exergy as the metric rather than temperature, and the work explains why this approach, common in optimising services components, can be applied to heating systems.
Renewable energy can play an important role in meeting the ultimate goal of replacing parts of fossil fuels to generate sustainable, inexhaustible, clean and safe energy. One of the promising applications of renewable energy technology is the installation of wind turbine that has been identified as having potential for wide-scale application in Hong Kong. Locally, wind turbines are seldom installed in building developments. The barriers include limited installation space available, the heavily obstructed external environments and noise and vibration problems. The apposite places for the installation would be on the roof/rooftop of low-rise buildings located in low-density zones. Relevant wind data and output power generated on-site, which may be quite site-dependent, are essential for modelling and evaluating the wind energy conversion system. Long-term measured wind data are crucial to the study of wind energy potential. This work studies the wind data and micro-wind turbine used in dense urban terrain and low-density area. Technical data including wind speed and output power were analyzed and reported. To achieve 1% of total building energy consumption generated from wind power, 17 micro-wind turbines are required to be installed in this institutional building located in low-density zone.
Practical application: Wind turbine is one of the typical applications of renewable energy technology. However, micro-turbines are not popularly installed in building developments. This work analyses the measured wind data and the energy performance of micro-wind turbines installed in an institutional building. The findings provide the on-site measured data for design and assessment of micro-wind turbines installed in building blocks.
A potential cross-transmission route, first identified in the spread of the SARs virus in South East Asia, in which infection was spread by virus-laden aerosolised droplets entering habitable space via defective water traps is investigated. The main aim of this work was to detect norovirus in wastewater from the collection drain in a hospital Building Drainage System and attempt to trace it in the BDS vent airflow. The methodology employed polymerase chain reaction tests on waste water samples and indicated strong positives for the norovirus GII strain from the collection drain, corresponding to an outbreak in the building, confirming that the BDS is contaminated in such circumstances and poses a threat. Pathogens were not detected in the BDS vertical stack airflows; however, the methodology employed to collect samples from the airflow was considered ineffective requiring further research. An average temperature of 24.3°C was recorded, together with an average humidity of 96.6%. This research also confirmed that inside the building drainage stack, air flow movement occurs in both the ‘up’ and ‘down’ direction. Thus, aerosolised pathogens could travel from the contaminated horizontal collection drains upwards and enter wards via defective traps or little used showers, sinks, baths and sluices.
Practical application: The detection of norovirus from raw, unprocessed samples taken from the collection drain of a hospital complex highlights the need for caution in dealing with these large contaminated systems. The obvious area affected by these findings is in the awareness by building managers and facilities managers that this contamination exists and that all appropriate measures are taken to minimise infection spread due to normal o&m operations. While it was not possible to detect the virus in the airflow itself, it is considered significant that the identification of the direction and magnitude of these airflows confirms that building drainage stacks could act as conduits for the transmission of aerosolised pathogen-laden water droplets. This research suggests that there is a need for a secure and verifiable seal between the building drainage/sewer network and habitable space within a building to minimize the likelihood of any potential cross-contamination and consequent risk to human health.
Absorption chillers, having thermal compressors, need a heat source at high temperature to obtain cold energy. Because thermal comfort needs are continuously growing, thermal wells placed near cities with high cooling needs might be exploited efficiently all over the year, and the payback time of these systems might be reduced. To investigate the possibility of geothermal energy utilisation for cooling, the parameters of geothermal wells were analysed in the North Great Plain region. From available geothermal wells database, some wells were chosen in order to see which the possibilities are to raise the calculated efficiency value. Based on the repartition of the temperature gradient in Hungarian territory, a diagram was developed in which the efficiency of thermal compressors variation versus well depth is presented. It was stated that deepening the analysed wells with 600–700 m, the efficiency of thermal compressor will be two to three times higher than the original value.
The loss of fixture trap seals presents a potential cross-contamination route for sewer-borne pathogens. The defective trap identification method was developed to assess the status of trap seals using a non-destructive ‘sonar-like’ test based on the reflected wave technique. System diagnosis, proven over several years of laboratory and sited-based validation, primarily depended on manual interpretation of system pressure responses to identify the trap location from the reflected wave return time. This paper advances the technique by introducing the developed ‘TRACER’ program which includes a time series change detection algorithm allowing automatic system diagnosis. Outputs were validated against simulations using the AIRNET numerical model which, together with the ‘PROBE’ Method, was used to determine trap pipe periods, and therefore the location of defective trap seals, with improved accuracy over those calculated theoretically. This technique thus provides a reliable and automated approach to monitoring the protective seal between habitable space and the sewer network.
Practical application: Once installed, the building drainage system is often afforded little consideration in terms of regular maintenance, due partly to the problem of the ‘out of sight, out of mind’ mentality which is so often associated with this fundamental system, but also due to the practicalities of executing such an onerous task. Armed with a greater appreciation of the health risks associated with fixture trap seal loss, due to understanding its role in the transmission of the severe acute respiratory syndrome virus in 2003, building owners, operators and regulators must take action to safeguard the integrity of this important protective seal.
The design of vertical transportation systems still heavily relies on the calculation of the round trip time (). The round trip time () is defined as the average time taken by an elevator to complete a full trip around a building. There are currently two methods for calculating the round trip time: the conventional analytical calculation method and the Monte Carlo simulation method. The conventional analytical method is based on calculating the expected number of stops and the expected highest reversal floor and then substituting the values in the main formula for the round trip time. This method makes some assumptions as to the existence of some special conditions (such as equal floor heights and a single entrance). Where these assumptions are not true in a building, this invalidates the use of the analytical formula the use of which will lead to errors in the result. The conventional analytical equation can be further developed to cover some of the special conditions in the building, but they do not cover all these special conditions and also do not cover combinations of these special conditions. The simplest round trip time equation makes the following assumptions: equal floor heights, a single entrance, equal floor populations and that the rated speed is attained in one floor jump. The case of unequal floor populations can be accounted for by amending the values of the probable number of stops and the highest reversal by using the formulae for the unequal floor population case. The work presented in this piece of work identifies the most important four special conditions (out a total of nine conditions) that are assumed in the classical round trip time analytical equation. It then develops analytical formulae for calculating the round trip time equation for any of the four special conditions or any combination of these conditions under incoming traffic conditions. A numerical example is given and verified using Monte Carlo simulation.
Practical application: This piece of work presents new equations that allow the designer to evaluate the value of the round trip time. The equations can deal with special cases such as top speed not attained in one floor journey, multiple entrances, unequal floor heights and unequal floor populations. Once the value of the round trip time is obtained, the elevator system can be designed, providing the required number of elevators, their speed and capacity.
Ground source heat pumps connected to a floor heating system can offer high efficiency for heating and cooling. However, the inertia of the floor heating creates a thermal lag that can lead to discomfort with conventional controllers. For this reason, a neural predictive controller for single-speed ground source heat pumps systems was developed. The objective of the controller is to minimize the energy consumption and maintain a good comfort level anticipating the thermal behavior of the building and external disturbances. A new neural network module for the heating power prediction of a single-speed ground source heat pumps system is proposed. The operation of the controller has been tested by simulation on a typical French dwelling during the month of March. In addition to an increase of comfort, numerical results showed that the predictive controller can provide up to 18% energy savings with the studied building in comparison with conventional controllers.
Practical Implications: Ground source heat pumps are currently equipped with conventional controllers that are not necessarily suited for such systems, leading to overconsumption and discomfort. In the medium term, ground source heat pumps could be equipped as standard with predictive controllers as presented here. Further work needs to be done to evaluate the feasibility of such an implementation as regards the return on investment and the controller’s robustness.
Energy demand attributable to the operation of supermarkets is thought to be responsible for 1% of UK greenhouse gas emissions. Current building regulations in the UK require the "building related" energy use of new commercial buildings to comply with particular requirements. Supermarket buildings are therefore modelled in considerable detail, according to these protocols to establish their predicted energy demand. Lighting, occupancy, and small electrical energy impacts are included in this modelling. However, a large gap is found between the design outputs of this modelling and the energy performance of the store in operation. One reason for this is that thermal interactions at the refrigeration cabinets are not included in this modelling, as refrigeration is classified as "process energy" rather than "building related." This paper explores the comparative energy demands of supermarket retail floors simulated both with and without the cooling effect of refrigeration cabinets included in the simulation. The retail floor of a recently built supermarket is modelled using EnergyPlus.
Practical applications: It has been shown that the energy demand of the retail floor of a new store could be reduced by 25% by improvement of the envelope, by halving ventilation rates and doubling insulation levels. This has been shown by simulation of the building energy flows with refrigeration cabinets included in the modelling (whereas these are currently excluded as process energy). Changes in modelling protocols, and regulations, to encompass refrigeration energy transfers, could reduce the national load, due to supermarkets, by at least 140 MW in 5 years. Energy costs to the retailer would be reduced by 20%. Additionally, the simulation has shown the contribution of rooflights to the reduction of energy demand to be lower than previously predicted, saving only around 1/3 of design expectations.
Representative, site-specific weather data is a key requirement for building performance simulation. In the UK, such data is available in two formats, Test Reference Years for analysing building services loads under ‘typical’ year conditions and Design Summer Years for estimating summer discomfort of naturally ventilated and free-running buildings. Currently, Design Summer Years are determined as a complete year based on the rank of the average dry bulb temperature from April to September. The simplicity of this approach does not take into account extreme temperature values in individual months or the incident solar radiation, both of which are however of great significance for the summer overheating performance of a building. This paper analyses the implications of this simplified approach for the resulting data. It is shown that there is no consistent relation between the Design Summer Years and the corresponding Test Reference Years and that, for some sites, building performance simulations using Design Summer Year files deliver unreliable results.
Practical application: This paper demonstrates that the current approach for deriving Design Summer Years (DSYs) can lead to data series that are not representative for near-extreme summer conditions at a given location. It highlights that a new approach for deriving near-extreme summer years for building performance simulation is needed in order to overcome the inherent shortfalls of the current DSY data.
This paper presents the findings of an 18-month study of detritus accumulation at two siphonic rainwater drainage systems installed in a building in Edinburgh. Findings are based on an analysis of data recorded from the site, and are positioned within the context of enhancing representation of the outlet loss coefficient used within both steady-state design calculations and finite-difference-based unsteady flow modelling techniques. The scope of findings reported herein is extensive but, in the main, shows how detritus accumulation not only builds relatively rapidly but also that ‘wash-through’ or ‘displacement’ occurs. Further, data suggest that detritus accumulation in the gutter, that is either wind-blown or is introduced from roof runoff, can, and does, build around the outlet with only relatively low intensity rainfall but that high-intensity rainfall events do seem to result in a direct and significant increase in blockage. An indication of the impact upon performance, assessed using simulation software, is also presented.
Practical application: This paper reports patterns of detritus accumulation at on-site siphonic rainwater outlets. Changes in detritus ‘categories’ are mapped to corresponding weather data and conclusions drawn on influencing factors. The paper therefore yields key information for building owners/operators on the extent of detritus accumulation at siphonic system outlets. Outcomes also inform designers of the potential shift in loss coefficient and flow performance post-installation.
This article presents an adaptive thermal comfort model study in the tropical country of Malaysia. A number of researchers have been interested in applying the adaptive thermal comfort model to different climates throughout the world, but so far no study has been performed in Malaysia. For the use as a thermal comfort model, which better applies to hot and humid climates, the adaptive thermal comfort model was developed as part of this research by using the collected results from a large field study in nine hospitals with 293 workers. The relationship between the operative temperature and behavioral adaptations was determined. In the developed adaptive model, the acceptable indoor neutral temperatures lay within the range of 23.3–26.5°C, with outdoor temperatures ranging between 25.4°C and 35.0°C. The most comfortable temperature for hospital workers was 26.4°C.
Practical implications: The new conclusions from the adaptive thermal comfort model in hospitals in the tropics could be used as an important guide for building services engineers and researchers. Their intentions are to minimize energy usage in HVAC systems in hospitals operating in the tropics while maintaining an acceptable thermal comfort level and thus improving the performance and well-being of hospital workers.
This article presents a study of airflow pattern inside a five-story wind-driven naturally ventilated atrium building. Firstly, field measurement conducted in the atrium building reveals the existence of reversed flows from the atrium to windows, which could cause air cross-contamination between floors during the period of an infectious disease outbreak. The computational fluid dynamics technique was then employed to further investigate the airflow pattern inside the building, under different wind directions and opening ratios. It is found that the airflow pattern inside a wind-driven naturally ventilated atrium building is very sensitive to the oncoming wind direction. Under parallel and perpendicular incident wind directions, the existence of adversely reversed flows in a certain floor and the re-entry of used air from an upper floor into its adjacent lower floors through the atrium results in the decrease of indoor air quality and the effective air exchange through windows. Nevertheless, the building has good natural ventilation performance under oblique incident wind direction, although the expected role of the atrium is still not fully achieved. In addition, the improvement of airflow pattern inside wind-driven naturally ventilated buildings cannot be achieved by simply modifying the opening ratios.
Practical application: Considering the indoor airflow pattern could substantially influence the elimination efficiency of pollutants and overheated air, this study is expected to help designers and engineers who are considering the use of an atrium at the design stage to have a better understanding of the airflow pattern inside a wind-driven naturally ventilated atrium building.
Water-saving facilities were constructed in response to the sustainability and global issues all over the world. However, the performance of drainage systems must be ensured as the volume of flush water is reduced. Otherwise, it might cause sanitary problems to indoor environments and interrupt building functions. According to the methodology of investigation and observation, this paper categorized parameters that dominate the solid transportation performance of main drains. An empirical experiment was executed to clarify the quantitative influence of these parameters. A calculation model for estimating the boundary condition of main drain design is conducted. Furthermore, an estimation interface is validated and proposed as an assessment tool for practical application.
Practical implication: This paper offers an evaluation tool by statistic methodology to ensure solid transportation performance. An estimating model and regulation proposal of solid transportation in main drains of buildings that can guide the designer and engineer to confirm the performance of drainage system is validated and proved to be practicable. Furthermore, this research conducted an estimation interface to validate the solid transportation performance, which can offer an assessment tool for practical application. The results can contribute to building code guidelines and lead to new technical development of building drainage systems.
Predicting the performance of internally cooled/heated liquid desiccant dehumidification system is complicated, which requires a large number of iterative calculations. This article numerically developed a quick prediction method for falling film dehumidifiers and regenerators in internally cooled/heated liquid desiccant dehumidification system by non-linear regressions, to predict the mass transfer performance directly with design variables, including inlet parameters of fluids (air, desiccant, and heating/cooling fluid) and system configuration (size, air channel thickness wetting factor, and flow pattern). The LiCl and water were chosen as the solution and cooling/heating fluid. Comparison shows that differences between our results and those by existing mathematical models are acceptable, with an average absolute error of 8.0% for dehumidifiers and 5.2% for regenerators. The prediction results also appear similar with previous experiment data, showing errors of less than 10%. The solution temperature has the greatest impact on moisture effectiveness and removal rate of internally cooled/heated liquid desiccant dehumidification system. Air humidity, air flow rate, solution concentration, and solution flow rate also significantly influence the system performance. Considering the limitations of practical projects, two more simplified equations with lower but acceptable accuracy were developed. This prediction method is very useful for researches and practical applications concerning the dynamic system performance.
This paper describes a full-scale experimental investigation into the effects of box gutter geometry on the open channel flow conditions above siphonic roofwater outlets. In particular, the effects of channel width (300, 400, 480 and 600 mm) and length (14.86 and 32.00 m) were investigated through measurements of flow rate, water depth and longitudinal velocity in the box gutter. The experimental results showed that for the same outlet flow rate, the depth of water in the gutter varied by up to 211% for the two different gutter lengths tested. Generally, the greatest water depths for the different flow rates were recorded in the 400-mm wide gutter and the lowest water depths were recorded in the 300-mm wide gutter. It was also found that the maximum flow rate through the single 110-mm diameter outlet varied depending on the width of the gutter.
Practical application: The depth of water in the open channel box gutters above the outlets of siphonic drainage systems is an important design variable and it is imperative to be able to accurately estimate these water depths during all phases of operation to reduce flood damage risk. This research study has found that for the same flow rate, varying the length of gutter on either side of a siphonic outlet strongly influences the depth of water along the gutter and above the outlet. The results suggest that there may be an optimum gutter width and length for which different siphonic outlets may perform more efficiently.
Monthly building thermal energy demand calculation procedures such as the utilisation method described in EN ISO 13790 and the monthly degree-day procedure contain parameters that reflect the variation of heating and cooling demands within a particular month. The frequency distribution of the loads is, however, neither explicit nor visible. This frequency information is important when calculating seasonal system efficiency and when apportioning load between the different fuels used in bivalent systems. This paper extracts the distributions embedded in the two procedures and examines the similarities and differences between them. It also illustrates how the distributions vary with the effective thermal capacity of the building. The report proposes appropriate areas of application for these methodologies, bearing in mind the levels of generalisation on which they are based.
This study proposed a method to construct urban hourly weather data by adopting the ‘morphing’ approach considering urban heat islands. The method starts with the surrounding rural weather as the ‘baseline climate’ and an Urban Canopy Model is used to provide the differences in the monthly average values of major climate parameters due to urban heat islands. The ‘baseline climate’ is then morphed to generate the urban hourly weather file for building simulations. It was demonstrated that the constructed hourly weather data agree well with the observations. When used for building thermal simulations, the differences between the proposed approach and the observation in the total energy requirement of space heating and cooling and heat stress risk index were within 5% and 1.0°C, respectively.
Practical applications: The proposed approach will allow academics and building engineers to construct realistic urban hourly weather data to analyse the impacts of urban heat islands on energy requirements and thermal stress for different urban planning and design options.
Due to recent studies and government policies, designers and facilities managers are becoming increasingly aware of the role of occupant behaviour in energy conservation in buildings. While the use of post-occupancy surveys and benchmark tools is widespread in the built environment, there is limited research on assessing environmental and energy saving behaviours – particularly in non-domestic buildings. This article focuses on the development and pilot-testing of a novel benchmarking tool for the assessment of behaviour change potential for energy saving in the workplace, with findings from an industrial case study comprising a manufacturing and office environment. Beyond the findings of the case study, the article aims to provide a methodological framework for an easy-to-use benchmarking tool of user-behaviour within the context of energy saving in factories and offices.
Practical Implications: This article discusses the development and pilot-testing of a novel questionnaire-based benchmarking tool for the assessment of behaviour change potential for energy saving in office and industrial settings. Its application to a case-study from the manufacturing sector demonstrates that the tool is easy to use, and it provides valuable insights on areas for improvement in energy use within non-domestic buildings, with a focus on user behaviour and management approaches. The tool can be used in applied research, for example in intervention studies for comparison within the same organisation (before and after), and/or for benchmarking against the performance of similar organisations.
This paper presents a literature review of the Fanger’s predicted mean vote and adaptive thermal comfort models developed in different buildings and climates. An important premise of this paper is the fact that Fanger’s model underestimates the thermal impression in the actual case and thus is no longer valid for use in certain climates. As a consequence, many researchers have developed adaptive models from field studies for different climates and countries. However, there is still no adaptive model that can be applied in designing air-conditioning systems for different buildings in all tropical climate countries. Based on this comprehensive review, an internationally recognized adaptive model is needed to achieve better thermal conditions in a variety of buildings such as hospitals, offices, factories, lecture halls, museums, hotels and libraries in the tropics.
Practical application: The new conclusions from the comprehensive review on an adaptive thermal comfort model in buildings in the tropics could be used as an important guide for building service engineers and researchers. Their intentions are to minimize energy usage in heating, ventilation and air conditioning (HVAC) systems in buildings such as hospitals, offices and lecture halls operating in the tropics while maintaining an acceptable thermal comfort level and thus improving the performance and well-being of the occupants.
An experimental heat pump utilizing wastewater discharged from the common bathroom in a SPA center as a heat source was built. In this article, the field measured operating performance of the wastewater source heat pump is reported. An analysis based on the collected field data under various operating conditions is included. It was shown that the temperature of wastewater greatly affected the evaporating temperature and the coefficient of performance of the wastewater source heat pump. Circulating wastewater from the bottom to the top of the wastewater storage tank could weaken even out the vertical wastewater temperature distribution inside the wastewater storage tank and improve the coefficient of performance and compressor suction pressure of the wastewater source heat pump accordingly. The daily averaged coefficient of performance of the wastewater source heat pump was monitored for over an entire month. It was shown that the measured coefficient of performance gradually reduced, suggesting the need for regular cleaning of the heat exchangers used in a wastewater source heat pump system. In addition, the recorded maximum transporting capacity of the wastewater pipe reduced by 16.9% over the 1 month operation and by 20.1% after ~5 months due to the bio-fouling build-up. Finally, an analysis comparing the economics of operating a wastewater source heat pump system with that of operating conventional water heating systems is presented.
Practical application: The use of heat pump to recover heat from wastewater is significant to energy conservation and environmental protection. A number of researches and projects on wastewater source heat pumps using urban sewage or treated sewage as a heat source have been carried out. However, field measured results on a heat pump, which recovered heat from waste bath water, was not previously reported. As the quality of waste bath water was different from that of sewage in terms of temperature, amount, and the degree of cleanliness, the experiences on designing and operating urban sewage source heat pumps previously obtained could not be used as a full reference for designing a waste bath water source heat pump. In this article, field experiment work of designing and operating a heat pump which used waste bath water as a heat source for hot water heating is presented, and the results can be used as a key reference for designing and operating waste bath water source heat pump systems in the future.
Retrofit insulated window shutters are examined. An initial investigation reveals that internal shutters are more viable in this context. Condensation is identified as a potential risk. Extensive investigations using modelling software as well as site and laboratory experiments are described which demonstrate that this risk is low. The thermal effectiveness of internal shutters is modelled and laboratory tested.
Practical application
This article results from research into the possibility of creating a retrofit thermal shutter system for existing commercial buildings. Building on earlier research, the paper examines whether this type of shutter is best fixed externally or internally to existing brick clad buildings and concludes that the latter is the best strategy. It then examines whether condensation between existing glazing and the outer shutter face is a problem and finds that this is not a significant issue. The way is clear for the development of this type of system as an alternative to costly triple glazing solutions.
The overall assessment of an intensive green roof located in a sub-tropical region has been undertaken. The results showed a fairly good agreement between the published and measured solar radiation data and also confirmed July and January as the hottest and coldest periods, respectively, for the region. The soil was established as a silt type with good planting medium properties for green roofs. The overall thermal performance showed that the green roof provided an average temperature reduction of 3.3°C (i.e. 50% temperature reduction) through the roof in July. Equally, its performance was remarkable during the coldest period of January. A maximum differential temperature of 15.5°C was achieved with the soil contributing to 24% of the temperature difference through the roof. Further studies are, however, needed to cover a wider area of influence such as effects of different types of construction materials, plants, locations and soil. In view of the limitation of the theoretical model, it would also be useful to consider some of the factors which were either neglected or assumed to be constant in any future comparative studies.
This article presents the results of water sorption properties investigation and thermal conductivity measurements of expanded polystyrene thermal insulation materials with different mass densities. The sorption behaviour of the expanded polystyrene materials was achieved in a Climacell 111 type climatic chamber, after drying in a Venticell 111 type desiccator apparatus. The relative humidity varied from 25% to 90% at 293 K for 240 min. The thermal conductivity of each sample was determined using a Holometrix 2000 (HLS) heat flow meter. In this article, the sorption isotherms, sorption kinetics, thermal conductivities and the prediction of changes in function of water content of four pure expanded polystyrene (30, 100, 150, 200 and grey) slabs with different densities (14, 17.5, 23.7 and 27.5 kg/m3) and one expanded polystyrene mixed with graphite are given (grey expanded polystyrene).
Practical application: The thermal conductivity as well as the moisture content are key thermal transport properties of building materials. The role of insulating materials in the building energy and moisture balance is more significant when compared with the other materials of the building structures. The laboratory measurements of these values of the insulating materials are very important either for the manufacturers or the contractors. The available bibliographic data for these materials are strongly incomplete and somewhere out of date.
Building drainage demands are assumed random and intermittent. The existing Hunter-based models have been developed to aid in the sizing of pipes for instantaneous demands but not to predict the occurrence and duration of such demands. This paper proposes a time series model to determine the occurrence and duration of drainage demand, which are greater than some predefined flow rates due to a number of appliances that discharge randomly and intermittently with variable flow rates. While the duration is resolved using the time series data for simultaneous demands, the occurrence together with the time-dependent flow rate is quantified via Monte Carlo simulation based on occupant usage patterns and appliance discharge profiles derived from appliance flushes at the base of the main vertical stack. The applicability of this model is demonstrated with example discharges from a number of water closet (WC) cisterns with reduced flush volume.
Practical application
This study will help designers determine the duration and occurrence of drainage demand due to a number of appliances that discharge randomly and intermittently with variable flow rates.
Energy efficient new and retrofit building construction relies heavily on the use of thermal insulation. A focus on the environmental performance of current construction materials with regards to both embodied energy and energy in-use has resulted in a growing interest in the use of natural fibre insulation materials. The results of heat flow meter thermal conductivity tests on a range of straw samples of different densities are presented. The innovative use of straw in the development of a prefabricated straw-bale panel and the results of guarded hot-box testing are presented. In common with most building materials, there is a degree of uncertainty in the thermal conductivity due to the influences of temperature, moisture content and density; however, from evaluation of a range of the literature and experimental data, a value of 0.064 W/m·K is proposed as a representative design value for straw bales at the densities used in building construction. Computer simulation and experimental testing suggest that the overall heat transfer coefficient (U-value) for the complete prefabricated panel is approximately 0.178 W/m·K. This article also briefly discusses the use of this innovative unit in a highly instrumented test building constructed at the University of Bath.
Practical application: Knowledge of the thermal properties of building materials is necessary for evaluation of energy performance of the building envelope and appraisal of retrofit fabric improvements. The presentation of robust data for the thermal properties of straw will be of interest to designers developing projects employing this natural fibre insulation material.
The sound transmission loss of a stiffened window was investigated using a coupled finite element and boundary element method. This approach allowed the window to have arbitrary elastic boundary conditions and the stiffeners to be located at arbitrary positions inside the window. The in-plane deformation of the window was also taken into account. The natural frequencies predicted by the present approach showed good agreement with earlier published results. The prediction method was subsequently applied to parametric studies examining the effects of stiffeners on the sound transmission loss of a window. The results showed that the stiffeners (or their locations) notably influenced the window’s sound transmission loss values, thereby demonstrating the possibility of using stiffeners to improve the sound insulation of a practical window.
Practical applications: This study provides an approach that can be used to predict the sound insulation of a window with arbitrary elastic boundary conditions and with any-shape stiffeners lying anywhere inside the window. This approach can also be used to guide the design of windows (or other plate-like building structures) with better sound insulation.