By Duane Amundson
My home in Wisconsin was well built in 1966, with extra insulation and good air sealing, attributes which have only recently become common in today’s energy conscious homes. What it did not have was adequate ventilation given its tight envelope. We found a solution for this problem by installing an Energy Recovery Ventilator (ERV).
We moved into the home in 1996. During that first summer, with air conditioning operating for several days, I noticed the house had a stale odor to it. I attributed this to the fact that the windows had been closed, and we were just cooling and breathing the same air every day. Some time later, we decided to install an ERV with hopes of improving the indoor air quality (IAQ). We were glad we did.
What is ERV Technology?
An ERV exhausts stale air with its fan, and brings the same volume of fresh air back in. A built-in heat exchanger allows the fresh air to be semi-conditioned by the exhaust air, so that you aren’t just tossing out air you’ve already paid to heat or cool. A master control timer runs the ERV fan from 6-60 minutes every hour to manage how much fresh air is introduced, based on the amount of activity or number of people in the home.
Following the ERV installation in my home, I also began investigating options for solving some bathroom ventilation issues we were having. Specifically, the bath fans were noisy and did not do a good job removing odors or humidity. The white ceiling above the shower was developing black and gray patches due to mold and mildew. At least twice a year, I had to carefully maneuver a ladder into the shower to reach the 8-foot ceiling in order to scrub it down with bleach. In between cleanings, the stains were embarrassing when guests came to visit.
The Problem with Bath Fans….
Manual on/off control of bath fans was part of the problem. One of two things always happen with this type of control. You either turn the fan off upon leaving the bathroom which isn’t a long enough run time, or you end up leaving it to run all day, which wastes energy. To solve this problem, I installed a timer wall switch that would operate the fan for a set period after it was turned on.
But this didn’t solve all of our problems. For one thing the bathroom fans vented directly into the attic, a common practice years ago, but one that is forbidden by most current building codes today because of associated moisture problems. I also wasn’t crazy about exhausting all that heated or cooled air from the living space every time we turned on a fan. So, I began to investigate ways to connect the bathrooms and the even the kitchen area to my ERV. That way we would be extracting some of the energy from the exhausted air to temper the fresh air being introduced into my home via the ERV.
ERV Does All the Work
With the help of an HVAC technician, ductwork from these areas was routed back to the ERV. I actually removed the inner workings of the bathroom fans, leaving that space free of obstructions to airflow, so that the ERV could pull air from the bathroom when we operated the timed switch. As a result, the measured airflow from the bathrooms nearly doubled that of the previous bath fans, and both bathroom and kitchen odors have been noticeably reduced.
More Energy Efficient Home Ventilation
For the past three years, I have activated my ERV daily with the timed bathroom switch for 20 minutes in the morning for showering, while the master ERV control automatically provides additional ventilation every hour. In terms of every day living, this change has resulted in my no longer having to clean the shower ceiling and the elimination lingering kitchen odors—even after a stir fry meal. And we don’t have to operate the loud kitchen fan as often as before.
I’m also not throwing away air that I have already heated or cooled just to ventilate the bathrooms and kitchen area, and the ERV is saving me energy (and money) that was previously wasted. Moisture isn’t being blown into the attic, and I no longer have to listen to the irritating drone of the bath fan when I am in the bathroom. My house is now a quieter, more energy efficient place to live.
Duane Amundson lives in Prairie du Sac, Wisconsin and has worked as an energy saving consultant for the past 10 years. He has incorporated many energy saving features to his own home, including CFL bulbs, ceiling fans, a more energy efficient light colored shingles, and an air source heat pump and a closed combustion gas fireplace insert. Plus, all his family vehicles are now hybrids. His other “green” claim to fame is that he was the very first Campus Recycling Coordinator at University of Wisconsin-La Crosse, when he was a freshman in 1973.