Modified Air Circulation: Energy Savings and Indoor Air Quality

John Gusdorf and Frank Szadkowski, Natural Resources Canada
Craig Simpson, Craig J. Simpson Technical Services
Mike Swinton, National Research Council Canada
T.J. Hwang, Enbridge Gas Distribution

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Abstract

An experiment at the Canadian Centre for Housing Technology (CCHT) showed that most of the energy savings achieved by more efficient furnace fan motors can be obtained by using low-cost, commercially available, programmable fan controllers with standard (PSC) motors. Energy efficient fan motors (brushless DC, or ECM) can save up to 75% of fan energy, but they are expensive, and retrofits to existing furnaces are not practical. The fan controllers are easy to install in houses with standard fan motors. The identical CCHT houses have mid-efficiency gas-fired furnaces with PSC motors. The experimental house was fitted with a fan controller while the control house continued to operate normally. Four different furnace fan schedules were run in the experimental house, and the consumption of furnace natural gas and electricity were monitored for several days in each schedule. To investigate possible effects on indoor air quality and comfort, carbon dioxide (CO2) was released in both houses, and CO2 levels and temperatures at several points were compared. The fan controller produced 49% to 65% reductions in furnace fan electricity, and 7% to 10% increases in furnace natural gas use, when compared with continuous circulation. This fuel switching results in net savings to homeowners, and if the saved electricity is fossil fuel generated, it results in net reductions of greenhouse gas emissions. CO2 levels did increase, but remained well below Health Canada limits, and within levels generally observed in Canadian houses. There were no statistically significant differences in temperatures.