Q&A: preparing for winter.

Q: I want to tighten up my house for winter. How do I find drafts and what is the best way to fix them?

Tightening up your house is a great retrofit project that will benefit your home, your wallet, and your health this winter. We receive many questions about the pros and cons of having a "tight" house. This leads me to believe that the general public isn't sure what to think of the concept. Most people immediately voice concerns about indoor air quality and the need for a house to breathe.

People intuitively know there's something not right about sealing ourselves up in a box and breathing the same air over and over and over again. It just doesn't make sense. This would, without a doubt, decrease the overall air quality of the living environment and the health of the occupants.

With fresh air being so important to people, why would anyone want to create a tight house? The answer can be summed up with the catchy phrase: "Build it tight, ventilate it right!" In order to create a healthy living environment, we need to know that the "fresh air" coming into the house truly is fresh. If we rely on holes in the building envelope to supply "fresh air" then the air frequently comes from not-so-fresh places like crawlspaces, basements, attics, and attached garages.

It's important to define the difference between tight and leaky, so we're all on the same page. A tight house is one that does not allow outside air into the living environment through unintentional holes, cracks, and gaps in the building envelope. A leaky house does allow outside air to enter into the living space through unintentional holes, cracks, and gaps in the envelope.

Studies indicate that the majority of air infiltration originates from the basement or the crawlspace--the bottom of the house. Since we heat our homes in the winter, this warm air wants to rise to the top of the house, often leaking out through small holes into the attic. When this air leaks out, other air leaks in to replace it. Basically, houses become huge chimneys in the wintertime. In fact, houses become two chimneys. One in the living space and one within the wall cavities--each of which are working hard to waste your hard-earned-money all winter long. The larger the opening in the top of your chimney (your house), the greater the suction is at the bottom of your house: increased leakage. This natural suction created by the unintentional holes in the building envelope is what introduces the not-so-fresh air into the living space and creates an unhealthy environment.

People know they want a healthy environment, but they also intuitively know that it is not a good idea to waste things ... especially their money. Through the years, we have found that the average house "leaks" its entire volume of air fifteen times per day. Doesn't this seem wasteful? What if you could cut that down to six or seven times a day? You could cut your heating bills in half! I think most people would agree that the less money sent to the utility company, the better.

So how do we achieve a home with good indoor air quality that is efficient and inexpensive to maintain? Well, I'm happy to say that you can have your cake and eat it too! By introducing fresh air (that you know is actually fresh) through your mechanical system's ductwork, you can tighten up your house as much as you wish-the more the merrier!

The major holes in houses are in the top and bottom of the house. Beginning in the basement or crawlspace, seal electrical and plumbing penetrations with caulk, foam, or any other material that will stop airflow. If you live in a home with diagonal 1-by subflooring, it may be in your best interest to have a foam insulation professionally installed, as it will save you a lot of time and caulk.

In the attic, seal around electrical boxes, duct registers, and exhaust fans that penetrate the upper-level ceiling. It is also a good idea to pull back the insulation that covers the top-plates of interior walls, air-seal the gaps along the edge of this top plate, and then re-insulate. These interior walls leak a tremendous amount of air into the attic. If you see any chaseways, or openings traveling between floors, cover them with a rigid material, air-seal the perimeter of this piece, and then insulate. Sealing around baseboards and window trim may also prove beneficial. But you'll get more bang for your buck by starting in the attic and basement/crawlspace.

Leaky ductwork is often times more detrimental to the efficiency of a home than air leakage through the building envelope. By sealing these duct connections with mastic, this leakage is eliminated. Tape should never be used on ductwork. It simply won't last. While you're at it, take the opportunity to ensure that all of your ductwork is properly insulated.

Now that your house and ductwork are tight, it's time to introduce air that is truly fresh. You have a few options here. The most cost effective way is to run a four- or six-inch duct from outside (the farther away from the ground, the better) to your return plenum. Ideally, this air supply would be filtered and this connection would be accessible from the inside of the house. Filters get changed more when it's convenient. Now, every time your air handler turns on, it pulls in some outside air. The drawback to this scenario is that you get exactly what's outside: hot, cold, wet, or dry.

The best option is to use an energy recovery ventilation machine. This machine brings air into your house and also pulls stale air out of your house. It has a heat exchanger, which passes about seventy percent of the outgoing heat (wintertime) to the incoming air, thus preconditioning it. It also runs the incoming air through a HEPA filter to remove particulates. These models also pass moisture from one air stream to the other, assisting in humidity control and mold prevention.

Both of these options allow your fresh air to be distributed to every room in the house, as they typically use your existing duct system for distribution. With either of these methods you know where your fresh air comes from, where it goes, how much you're getting, and you're able to pre-filter and pre-condition it.

Now that you understand how to tighten your house and improve your indoor air quality, it's time to get to work! Regardless of how macho you may be, don't forget your respiratory mask ... you'll need it. Old insulation in the attic and who-knows-what in the crawlspace will certainly be much easier to work around when you protect your lungs and your sniffer.

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Isaac Savage is president of Home Energy Partners, a Building Performance Contracting firm that is located in Asheville, NC. He can be reached at 828-350-1155 or on the web at www.HomeEnergyPartners.com