Seal tight; ventilate right

Posted on Nov 29 2016 in Energy, Product Picks

By Patrick Keegan and Amy Wheeless

Blower door

Parke County REMC energy advisor Jeremy Montgomery programs a blower door before beginning a test for a consumer to measure air infiltration in the home.

Now that winter is here, I’d like to make my home more comfortable by keeping cold air out. I’m planning to have a contractor inspect and seal air leaks. However, a neighbor mentioned that I could seal up my home too much and cause ventilation problems. Is this true?

Sealing air leaks is usually one of the best energy efficiency investments a homeowner can make. A typical home leaks about half of its air every hour, which is like having your kitchen window open all day, every day. Sealing leaks can also eliminate drafts that keep your home from being cozy.

It is possible, though, to seal up some homes so “tight” they have little ventilation. This can contribute to indoor air quality problems or a build-up of moisture. The challenge is to achieve the best home performance and energy savings while maintaining air quality.

The first step to take is to eliminate or reduce indoor air pollutants. Experts then recommend sealing air leaks as much as possible and installing mechanical ventilation, as needed. Simple mechanical ventilation can be controlled and consistent, as opposed to “natural” ventilation from air leaks, which can result in a home being too drafty in colder weather and not ventilated enough in milder weather.

The best way to inspect your home for air leaks is to have a contractor or energy auditor to conduct a blower door test, which uses a powerful fan to measure the air infiltration rate. Many of the state’s REMCs have energy advisors who will do this for you or can give you names of local contractors.

There is no simple way to determine how much mechanical ventilation your home will need — it depends on a combination of factors, including how your home is constructed, what kind of climate you live in, and whether there are other indoor air quality concerns, such as combustion appliances like gas furnaces.

Mechanical ventilation systems allow for controlled air movement and a rate of ventilation, helping ensure good indoor air quality and appropriate levels of moisture.

There are two primary categories of mechanical ventilation:

Spot ventilation systems are the fans that you find above your oven range, in your laundry room, in your bathroom and perhaps above a garage workshop. They focus on removing moist air and indoor air pollutants at the source.

Whole-house ventilation circulates air throughout the home and introduces the right amount of outside air.

There are four categories of whole-house ventilation systems; determining which method is best for you will depend on your home’s needs, your budget and your climate:

 Exhaust systems: Fans pull air out of the home, which increases infiltration from the outside.

 Supply ventilation systems: Fans bring outside air into your home.

 Balanced ventilation systems: Both supply and exhaust fans circulate air in and out of the home.

 Energy recovery ventilation systems: Fans, combined with heat exchangers, modulate the temperature and humidity of incoming air.

Ask your energy auditor whether you need additional mechanical ventilation, and if so, which system would work best for your living space.

Patrick Keegan writes on consumer and cooperative affairs for the National Rural Electric Cooperative Association, service arm of the nation’s 900-plus consumer-owned, not-for-profit electric cooperatives based in Arlington, Virginia. Amy Wheeless writes for Collaborative Efficiency. For more information, or email Pat Keegan at