An energy efficient home
can be a healthy home
UPdate Fall 2007
Saving energy is a win-win move good for the environment and good for the wallet. As winter nears, thoughts turn to reducing heating costs at home. Stopping air leakage by tightening up the house is an obvious way to save on heating bills. Weatherstripping, caulking, and placing a seal over windows are all good ways to reduce air leaks and energy loss.
However, people can try to save heat in the wrong ways, ways that can have serious health risks. Professor Tang Lee teaches Building Science at the University of Calgary’s School of Architecture. He’s seen people make some bad mistakes trying to save energy in the wrong ways.
“ Some people try to save some of the heat from their clothes dryer, Lee explains. “They disconnect the hose that goes to the outside, because somebody said ‘Oh, the humidity is going to be good for your house, the filter in your clothes dryer is going to filter all the lint.’ But the large lint which is captured by the lint filter is not hazardous to your health. It’s the smaller particles that come out of your clothing which are very harmful, that go deep into our trachea, into our air sacs, and of course they are too tiny to be filtered out by the lint filter.”
Another consequence of not venting the clothes dryer outside is that all the chemicals in the laundry, fabric softeners, clothing dyes, other cleaning chemicals, give off more fumes when they are heated up. “There is absolutely no way that the filter can catch those chemicals,” says Lee. “People have a misconception that a filter filters out everything. No it doesn’t. So you are breathing in absolutely all of those chemicals.”
The simple act of disconnecting a dryer hose can have even more harmful results. “The humidity that is coming out of the clothes dryer can cause molds,” Lee explains. “It can increase humidity levels in the house and you can get condensation, what we call intersticial condensation, meaning not just the condensation on the window pane, but inside the wall or in the attic. Lee says you don’t see this type of condensation “until its too late. It eats away your building. You get rusting steel, rotting wood. That humidity from the dryer can exceed the ability of what we call the building envelope to withstand.” In addition, the small lint which circulates through the house can become a food source for molds.
Bottom line: “We don’t recommend that people do that. The heat that you save is not significant,” Lee says.
Closing off a combustion air duct for the furnace is another way people may try
to save energy, not realizing that this is extremely hazardous.“People go down
to the basement and say, “Oh, this basement is cold. Oh, look at that, there’s
a big hole, 8” diameter, 6” diameter, a duct that’s coming directly down to the
floor, no wonder we are getting cold in this house, we want to save energy.” So
they plug it up, they put a garbage bag over it, they even throw socks in there,
stuff it with towels, because they don’t understand that any combustion furnace,
including fireplaces and wood burning stoves, has to have an outdoor source of
air. When a furnace burns, it consumes oxygen. Without air coming in, nothing
is going to go up the chimney.
Plugging up that air intake duct can cause chimney
backdrafting which can result in carbon monoxide poisoning. Every year about
two dozen Canadians die due to chimney backdrafting, and thousands more get sick.
“That happens because they don’t understand the function of those things,” says
Lee. “Just because there is a hole doesn’t mean there is a problem. Tightening
up really means only tightening up the envelope, not those areas that have other
Even tightening up a home the right way can have unexpected consequences. It
is especially important for tight homes to have fewer indoor pollutants, explains
Professor Lee. When there is less air leakage, contaminant levels in the house
will go up, because the contaminants are not diluted by outdoor air. The more
pollutants, the more the health of the people in the home is at risk.
to two major sources of indoor air pollution which can lead to health problems.
These contaminants are health risks whenever they are present, but their risk
increases as homes are tightened up.
Mold is one, says Lee. “When you enter the house, is there a musty odor? A musty
odor means there is mold growing there, and that’s not good for you. So, one
should try to find out where the molds are coming from, and get rid of it. Once
that is gotten rid of, the house is cleaner and you don’t need so much ventilation.”
more information on safe and effective mold removal, see Canada Mortgage and
Housing’s Fighting Mold - The Homeowner’s Guide at
The second is volatile organic compounds, VOC’s for short. They come from many,
different sources. “There are about 63,000 chemicals in the home,” says Lee. “The
books that you have, the clothing that you wear, the dry cleaning solutions,
the Scotchguard you may be putting onto your carpet, there are so many chemicals.
We are also bringing in devices that we have never had in the past, like laser
printers and photocopiers. Some of them off-gas more than others, and some are
more toxic than others.”
The trend to stronger and stronger cleaning products is another significant source
of pollutants. Lee points out that people often think they need a product which
will “eat up dirt and grime” - but they don’t realize that in order to do this,
the cleaning chemical would have to be very strong - and those strong chemicals
then off-gas into the home and can make people sick. Milder products can be just
as effective at cleaning, only take a minute or two longer to use, and do not
put people at risk.
Lee’s advice is to decrease the chemicals that you bring into your house. “Don’t
bring in any air fresheners, they do not freshen air, they just mask over the
odors that are still there, and that can be even more polluting. Buy non-scented
cleaning solutions. Why do we have to have lemon smell in our clothes, in our
dishes? Those are just more chemicals which add to the pollution in our house.
I would even say, don’t buy perfume. Obviously, don’t smoke, and don’t burn incense.”
Especially in homes which are not equipped with air exchangers or ventilators,
keeping the house free of mold and pollutants can help avoid that “closed up” feeling
houses often get in winter. Lee also believes in the basics what he calls “good
house hygiene.” Lee compares it to body hygiene - washing hair, taking a bath,
brushing your teeth. “You have to think about a house that way, you have to clean
it, it has to be hygienic. Not go overboard and spray everything with Lysol,
that’s no good either. Just keeping it clean. You have a pizza box, throw it
away. Garbage is piling up, get rid of it. Meanwhile, vacuum and dust,” says
Lee points out that ventilation is an important aspect of a home environment. “The
building code is very clear, we should tighten up the house, but then we have
to bring fresh air into the building.” In buildings which don’t have air exchangers
and ventilation fans, people can use bathroom and kitchen fans and even central
vacuum systems, to help exhaust air out. It is important that these units be
Many people ignore instructions which say “use in well ventilated area.” Whether
it’s a printer, a cleaning product, or renovation materials, these instructions
are there for a reason. Ignoring them results in higher levels of indoor air
pollution and increased health risks.
Tight houses help save energy and reduce greenhouse gases. Reducing pollution
inside the home will ensure that a tight, energy efficient house is also a healthy