Building air entry can occur by air moving into the home through cracks and voids and by air moving from the inside to the exterior of the home. Excess air movement increases energy costs in the home and can make your home drafty, humid or too dry. There is a balancing act that needs to be performed when designing and building a home. Too much air leakage can cause a drafty and cold house and lead to higher energy costs.
The paths to air leakage are most often found in penetrations drilled for plumbing, electrical, vents, and other utility services. Also devices installed on the exterior of the home such as light fixtures and outlets, can also greatly contribute to air leakage in the home.
One area of probable air leakage that gets ignored are the spaces between the bottom of the sill plate and the foundation walls of the home. In newer constructions there is usually a foam gasket installed. In older construction there are usually gaps that will also a lot of air leakage into the basement. Foam insulation can be installed into these gaps to help keep air leakage to a minimum. The areas where patio doors and windows attach to the home should also be sealed in order to prevent air leakage. Use silicone caulk in order to seal these areas. Silicone caulk is flexible and will stand up better to changes in weather. Avoid using fiberglass insulation to fill gaps. Fiberglass batt is porous and does not stop air movement effectively.
Another area that is neglected and can cause a great deal of air leakage is the perimeter bands in between the floors of the home. Air can enter through gaps in the siding and travel far into the home away from its entry point into the home.
There are many products on the market to help you seal the air leaks in your home. Caulk can be used to seal smaller holes or gaps. Expandable foam can be used to seal up larger holes and gaps. Rope caulk can also be used to seal up areas around windows and doors. There are foam gaskets that can be purchased to seal areas behind outlets and other penetrations. Weather stripping can be used to make windows tight in their frames.
Older homes can benefit the most from air sealing measures. It is easier to do this type of air sealing when the home is under construction or under renovations. Stopping air leaks is a very cost effective method to lower energy bills in your home.
One very effective way to check for air leaks is to hire a professional that uses a device called a blower door. The house is closed up and the large fan that is installed in the doorway exhausts air to the outside. While operating the blower pulls outside air through the gaps located around the home. Air flow through the fan can be measured using flow meters. The method is also very effective with isolating the various air leaks in the home.
Often infrared cameras can be used in conjunction with the blower door. Infrared will tell you where the home is loosing energy by exposing areas of air leakage. Infrared will scan the home using a blue and red color spectrum to detail where the home is leaking air. Areas of blue are the coolest areas and areas of red indicate hot areas. Depending on the time of the year and temperatures the infrared camera can show you where to install additional air sealing measures.