While keeping conditioned air in the home has been a recurring theme in my columns, it is also very important to address the removal of unhealthy air from inside the home.
Bathrooms are locations that regularly generate undesirable air. Exhaust fans, used to remove this air, should be located in every bathroom. But the quality and proper installation of this equipment are the keys to their effectiveness.
Bathrooms, where we shower and do other hygienic activities, introduce a considerable amount of moisture into the air. This humidity can result in mold and mildew growth, the consequences of which can be unhealthy air for breathing and potential degradation of building materials within the home. It is the bath fan’s function to eliminate this air by pulling it out of the room and dispensing it outside the home.
But not all bath fans are created equal, and not all installations maximize their effectiveness.
Fan performance is measured in “cfm,” or how many cubic feet of air is removed in one minute from any given space. Energy Star, the joint program of the Environmental Protection Agency and the Department of Energy that assists Americans in protecting the environment through energy-efficient products and practices, requires bath fans to have a minimum 50 cfm installed performance in its new home specifications.
Keep in mind that the effectiveness of all fans will lessen upon installation, so to achieve an installed yield of 50 cfm one must have a fan with a higher rating. For instance, bath fans rated at 80 cfm consistently test above 50 after installation. However, results will vary because of the way in which a fan and its ducting are installed. The best fan’s performance can be nullified by poor installation. Length and curves are the obstacles to optimizing fan effectiveness.
According to Canada Mortgage and Housing Corp., “Straight, short duct runs, with few turns, will result in the highest fan flow.” It is a good idea to check the ducting on your existing fans for these things as well. I also recommend inspecting the outside termination point of your duct. I have frequently found the back draft damper flaps off or bent, bringing outside air into the ductwork and creating nice warm locations for birds and bees to build nests.
Once you have a high-quality, well-installed fan in your bath, make sure it gets used. Any fan that does not get turned on yields zero cfm.
I frequently wire bathroom fans to turn on with the light in the bathroom. This guarantees they get used often. For households with absentminded teenagers, a situation I understand from personal experience, there are fan switches available that are humidity controlled and motion sensitive. Timers are also available so that the fan will operate after the user has left the bathroom.
As we construct our New Year’s resolutions for 2011, let us include improving the air quality in our homes as well as reducing waste and pollution on our planet. Happy New Year!
Gary Silverstein, chairman of the Triad Green Building Council, is owner of Silverstein Construction Corp. and president of Energy Reduction Specialists of N.C. Inc. He can be reached at gary@silversteinconstruction.com or 643-9199.
