A Field Study of Ventilation System Effectiveness in Low Air Leakage Residences

This paper reports on the results of a field study of five different ventilation system types in 29 homes in the Pacific Northwest. The homes studied ranged in air-tightness from just over three air changes per hour at 50 Pascals to less than one. Carbon dioxide, relative humidity and temperature were monitored in multiple rooms in both the heating and shoulder seasons while residents performed week long experiments with bedroom doors open or closed and ventilation systems on or off. Residents were asked to keep journals of these actions and use of auxiliary fans, and bedroom door closures and ventilation fan status were also monitored. In addition the paper reports the results of one-day tracer gas decay tests done on 26 of these homes. The paper compares the measured effectiveness of the five types of ventilation systems in terms of removing site-generated CO2 and tracer gas. It also assesses the impact of house tightness on ventilation performance and the fan electricity invested in providing ventilation. Resident knowledge of their ventilation systems, maintenance of systems and as-found control setting impact on ventilation effectiveness are also reported.