Fans and Exhausts
Homes without adequate ventilation can experience a variety of problems with indoor moisture, odors, and pollutants. Moisture from cooking and bathing needs to be removed before high humidity levels lead to mold growth and/or physical damage to the Portage, MI, area home.
Too little ventilation can allow unpleasant odors to linger. Contaminants like formaldehyde and volatile organic compounds (VOCs) can accumulate and may cause health problems in poorly ventilated homes. Typically, newer, or recently air-sealed homes have less natural ventilation, which means these pollutants aren’t regularly flushed out of the home.
The issue isn’t that these homes are too “tight”—it’s that they not “breathing” properly. Mechanical ventilation, in the form of bath fans and kitchen exhaust fans, allows homeowners to better control the breathability of their home, improving indoor air quality in the long term.
These fans typically have two to three speeds which can be controlled by a motion sensor or switch. The continuous or low speed setting is typically 30-50 cubic feet per minute (CFM). Higher speeds are used when bathing (50-110 CFM) or cooking (more than 100 CFM).
In terms of duration, we recommend running fans at high speed for 20-30 minutes to clear out excess moisture and odors. The installers at Better World Builders will set the exhaust fan ventilation speeds based on the number of occupants or bedrooms and the home’s tightness.
Better World Builders recommend running the fan continuously, 24/7. By running it all the time, the fan can be set at a lower very quiet speed. The savings from air sealing and insulation work are typically much greater than the small amount of air the fan removes from the home. The benefits of healthier indoor air quality by removing indoor moisture, odors, and pollutants usually outweigh the additional cost.
These fans are pulling air from air leaks, cracks in your home, and/or a combustion air inlet (a flexible ductwork tube that goes into your mechanical room). A considerable amount of conditioned air can leak through these gaps and into the unconditioned attic space, which can create air pressure imbalances, leading to a host of secondary issues related to energy efficiency and comfort.
This is why Better World Builders always recommends proper air sealing and insulating your home for true indoor air quality improvements. When we install fans in your home, we make sure to seal them around the trim to stop air leaks from occurring.
If your ventilation fans are not air sealed the pressure and temperature differences between conditioned and unconditioned spaces encourage air flow where these leaks occur. Such air leakage represents energy loss.
It could also potentially allow warm, moisture-laden air into unconditioned attics, where it can condense on cold surfaces, creating moisture problems, including mold growth. Air barriers need to be continuous to be effective; this means sealing all penetrations in exterior walls, ceilings, and floors adjoining unconditioned spaces.