AC-2337 -- Dynamic Characteristics of Air Infiltration ✓ Most Recent

In the design of a building, the heating and cooling load should be calculated accurately in order to properly size the heating and cooling system and to make a suitable prediction of the seasonal energy requirements.

Energy is added to or taken from a structure in a variety of ways: conduction of heat through the solid portion of the structure; thermal radiation through transparent surfaces such as windows; the addition of energy from people and equipment inside; and finally the energy associated with the air that is either introduced through the ventilation system or continually infiltrating into and exfiltrating out of the structure. Of all these factors, infiltration is perhaps the most difficult to predict and can be as much as 1/3 of the heating load and even a larger percentage of the cooling load.

The ASHRAE HANDBOOK OF FUNDAMENTALS (1) describes the two basic techniques used in predicting air infiltration rates. Much research has been done to refine the design calculations of heating and cooling loads, and in particular, the infiltration portion as it applied to complex buildings and structures. The purpose of this study was to determine, experimentally, if meaningful infiltration data could be obtained from observing this fluctuating wind speed and pressure difference exerted on an enclosure. In addition, an attempt was made to evaluate the correlation between these two dynamic variables.