Home Performance Energy Audit
Making a Difference
Saving hundreds of dollars thanks to an energy audit at their last home, Kerry and Brian Hogg were eager to do it again when they moved. But saving money isn't all they care about. "Looking at our energy use at home is one way we can make a difference," Brian says.
The first step in a home performance energy audit is to insert a device called a blower door into an exterior doorframe. When the fan is turned on, the auditor measures airflow to determine how tight the house is. After improvements are made, the test is repeated to determine the effectiveness of any changes.
How It Works
A fan blows air out of the house, creating a negative pressure inside. The blower door test reveals air leaks in the envelope of the home, often hidden behind insulation. Sealing the leaks makes a home more comfortable, healthier, and more energy efficient.
Another instrument used in a home performance energy audit is a thermal scanner. This infrared device provides a visual representation of hot and cold spots wherever it is pointed. Viewing the handheld screen aids the auditor in identifying problem areas that can often be addressed in the improvement phase.
An energy audit is not all high-tech. Here, a visual inspection reveals a chimney damper left partly open to vent fumes from the pilot light of this gas-log fireplace. Installing a glass door and keeping it closed will help prevent heated air from going up the chimney.
Sealing Supply Ducts
A big part of an energy audit is examining the HVAC system (heating, ventilation, and air conditioning). Here, the supply ducts in the bathroom and bedroom aren't adequately sealed, letting in air through the house overhang. Caulking the supply boot (the gap between the heating supply duct and the subfloor) will prevent this leakage.
The auditor found large leaks at the duct trunk and floor framing above the furnace. Sealing with mastic, expanding foam, caulk, or tape will make these joints airtight. The result will be a more even distribution of conditioned air throughout the house.
Gaps in Construction
Gaps and cracks between construction materials have their origin either at the time of construction or as the result of settling. Here, the sill plate and the foundation wall cause air leakage and heat loss. Expanding foam will effectively plug the gaps.
A little thing such as an uninsulated attic access door produces an enormous amount of heat loss. Insulating and weather-stripping the door will solve the problem.
Checking Under Insulation
It is important to pull back the insulation to check for air leaks wherever dissimilar construction materials come together. Here, the floor insulation in the attic is adequate, but some gaps exist between framing and drywall. Expanding foam will fill these gaps.
Insulating Wire Pathways
Holes to accommodate wires through exterior walls allow air loss. Expanding foam squirted into the holes will easily solve the air leakage problem.