The need for efficient, sustainable, and planned utilization of resources is ever more critical. Several building energy analysis tools have been developed to assess energy demands and lifecycle energy costs in buildings. Such analyses are essential for an efficient heating, ventilation, and air conditioning design that overcomes the pitfalls of an under/over-designed system. Studies have estimated air infiltration accounts for up to 50% of a building’s energy demand. This stresses the need that energy simulation engines accurately account for air infiltration. An Enhanced Model for air infiltration has been developed.