Mechanical Air Distribution and Interacting Relationships

It has been determined from extensive testing conducted between May 1987 and May 1988, in the hot and humid climate of central Florida, that pressure differences within the envelope of residential housing exists. These can range from near neutral to pressures, either positive or negative, as great as 0.24" W.C. (60 pascals). Reasons sighted and discussed in this paper include duct system design, duct system failure, airtightness of the residence and human interactions. This testing further reveals that one of the largest driving forces in air change rates can be attributed to mechanically induced infiltration and exfiltration. Airtightness can also drastically affect this pressure difference within the envelope. In conclusion, the effects of these pressure differentials on energy consumption, indoor air quality, comfort, and degradation of building materials will be discussed. Possible solutions and practical field test protocol to correct these ill effects both in new and existing residential housing will be covered