equipment sizing

In the United States, the realm of building enclosure design and commissioning is separate and distinct from the realm of mechanical design and commissioning. This paper will illustrate how and why these disciplines have been historically separated and outline the consequences of this division and describe the opportunity that a closer relationship between the two represents in terms of costs and environmental impact.

Cracks in building fabric lead to air infiltration due to wind and buoyancy driven forces. In the heating season, the cold air entering the building needs to be heated up to room temperature, thus leading to an energy demand. Conventionally, the measured infiltration rate at 50 Pa (expressed as n50 or q50) is recalculated into an average infiltration flow rate (yearly based) using leak infiltration ratio’s (LIR) ranging from 0.033 to 0.1, the origin of these values being sometimes unclear.