The Prediction of Air Infiltration

Air infiltration is responsible for about one-third of the space conditioning loads in
residential buildings; it is also the principal method for maintaining adequate indoor air
quality (by diluting internally generated pollutants). Recent recognition of this dichotomy
has increased the desire for a simple and reasonably accurate method for estimating
air infiltration. This paper describes such a method in a practical manner so that
engineers or auditors who are not specially trained in infiltration research can estimate air
infiltration. The predIction of air infiltration with this method requires two steps: field
measurement of the building properties, and calculation of the infiltration from weather
data and the measured properties. In this paper we will describe fan pressurization techniques
(e.g. blower door) and how to use them to measure the air tightness of the building
envelope, and we will describe the procedures required to make infiltration predictions
with the Lawrence Berkeley Laboratory (LBL) infiltration model.