This cold windy weather is a great time to find and repair air leaks in your home. It turns out that air sealing your home is just as important as insulation in maintaining comfort and reducing utility bills. Run your hand around the perimeter of windows and doors. If you feel air movement there is a leak that needs to be fixed. Other likely places to find leaks are at light switches and outlets. Also plumbing penetrations such as under sinks can provide opportunities for leaks.
Often these leaks are easily fixed by homeowners with caulk or canned foam insulation.
We think of drafts as coming from wind pushing air into the home, but the opposite also happens. On the leeward side of the house a negative pressure is created which sucks air out of the house. When outside air is forced into a house the same amount of conditioned air is forced out of the house. These leaks can often be felt as a slight breeze.
While a cold blustery day is a good time to identify air leaks in your home, it is not the best method. When we do an energy audit, we use a piece of equipment called a blower door. The blower door depressurizes the house allowing us pin point leaks. The blower door also allows us to calculate exactly how much leakage the house has under a set pressure differential between the inside and outside.
In most homes a large number of leaks will be found in the attic. These leaks tend to be more difficult to find and to seal, but they are a crucial part of reducing energy loss. Unless you have an unvented attic, which is relatively uncommon, in the summer your roof acts like a solarcollector heating up the attic and forcing hot air out the attic ventilation. This air movement creates a siphon effect (also known as the stack effect) that pulls conditioned air out of the house.
The best way to deal with energy loss through stack effect is to have an unvented attic. In an unvented attic insulation is placed at the rafters rather than the joists. The rafters are the framing members that create the roof and the joists are the framing members that create the ceiling. Also, all venting to the outside is removed. This creates multiple happy results. By putting the insulation at the rafters, we prevent heat and cold from getting into the shell of the building. Also insulation at this location, especially foam insulation, helps better air seal the house, stopping the stack effect.
Most AC ducts run through the attic and they tend to be leaky. In a typical vented attic we are running our air conditioning ducts through super heated attic air resulting in significant energy loss.
New homes should be built with unvented attics. Often this is a good consideration as a retrofit solution. But there are several circumstances that can make this a less desirable option as a retrofit. Low pitched roofs make it difficult to properly insulate the crucial area where the roof meets the outside wall. Combustion equipment such as furnaces and water heaters in the attic make retrofitting an unvented attic more difficult and costly. Without ventilation to the attic combustion equipment must be separated from the rest of the attic to provide fresh air in order to prevent back drafting.
We encourage everyone to have an energy audit done on their home. This is a relatively small investment that will pay off through energy savings very quickly. In many homes air sealing the attic will be a good option to pursue. Like replacing incandescent light bulbs with CFLs, these things are the low hanging fruit of home energy savings and, in most circumstance, should be considered before more costly efforts such as window replacement.
If you are in the Brazos Valley and interested in having an energy audit done on your home, call our office for scheduling.