Ventilation system performance evaluation using tracer gas techniques.

Based on current concerns regarding indoor air quality and energy use, there is a need for in situ techniques for evaluating buildings' infiltration and ventilation characteristics. The U.S. National Bureau of Standards has developed and employed equipment and techniques for such evaluation. The measurement of whole building leakage and ventilation rates has been reported on previously. Additional procedures are presented here for a more complete evaluation of the ventilation system operation and the distribution of air within the building. The measurements reveal both the amount of outside air infiltrating through the envelope and the amount of intentional intake through the air handlers, Tracer gas techniques to study the uniformity of air distribution throughout a building are also discussed. These in situ evaluation techniques are described and results from their application are presented. The measurements reveal that, in some cases, a significant amount of a building's net ventilation rate is due to envelope leakage as opposed to intentional outside air intake through the air handling system. Also, air distribution inadequacies are often encountered in buildings , leading to effective ventilation rates of occupied zones which are less than intended or advised.