Energy Saving Ideas

Find and Stop Air Leaks

A home is a complex system of interacting units that work together to keep it running. By making a few changes you can increase the efficiency of those systems and reduce energy bills. There are numerous areas with in the home that should be checked and sealed to reduce the amount of air leaking both in and out.

Dealing with Your Ducts
Because of duct leaks, gaps or improper installation, 24-40 percent of the heating and cooling energy used in a home may be lost. To decrease the amount of energy and resources lost in ducts, locate gaps and leaks, paying close attention to curves or joints where ducts are placed together. Patch gaps with mastic tape or aluminum foil backed duct tape, fasteners or butyl tape. Be sure to look for tape with the Underwriters Laboratories (UL) logo to avoid tape that degrades, cracks, and loses its bond over time. Duct tape is actually not the best solution for these leaks as the ducts are often in dirty, dusty places where the tape will dry and lose its adhesive power. For leaks that are hidden in walls, a contractor can use an aerosol-based mastic.

It is impossible to accurately estimate the tightness levels of a home by visual inspection alone. Consider contracting a local energy technician, ventilation or duct cleaning service for a duct blaster or blower door test to evaluate the duct system.

A duct blaster test will directly pressure test the system for air leaks, similar to how a plumber tests water pipes for leaks. First, the duct blaster fan is connected to the duct system at the air return grille or air handler. After sealing all remaining registers and grills in the home, the duct blaster fan is turned on to force air through all holes and cracks in the ductwork. A technician may use a non-toxic fog machine to indicate where leakage is occurring. The pressure gauges on the duct blaster help estimate efficiency losses from ductwork leakages.

The blower door test also uses air pressure to reveal hard to find leaks in a home. The test pinpoints the air leakage areas and measures the magnitude of air infiltrating the home. To conduct the test, a professional installs a fan into an exterior door of the home. All other exterior windows and doors should be closed while interior doors remain open. When the fan is turned on, the inside pressure of the home is reduced. With a stronger outside pressure, air flows into the house through cracks or unsealed openings from the outside. A pressure gauge connected to the fan determines what rate of airflow is required to maintain the homes inside pressure, indicating just how much air is entering through leaks. The professional can feel the leakage areas by hand or use a smoke puffer to show infiltration spots. These problem areas can then be sealed.

The Attic:

• Holes in the attic floor and walls
  
• Doors and hatches to the attic
  
• Plumbing stacks
  
• Attic knee walls/storage drawers
  

The Basement:

• Around the sill plate and band joists
  
• Around basement windows
  
• Ducts
  
• Openings in the basement walls and ceiling including dryer vents, electrical wiring, plumbing stacks, etc.
  

The Main Level:

• Around the chimney and fireplace dampers
  
• Around windows, doors, trim and baseboards
  
• Electrical outlets and other exterior wall openings
  

The Outside:

• Cracks in exterior siding
  
• Around windows and doors
  
• Around outdoor faucets, vents and electrical outlets

More Information and Additional Resources
Some of this information was adapted from the American Council on an Energy Efficient Economy's publication, Consumer Guide to Home Energy Savings, 7th Edition, the Energy Efficiency and Renewable Energy Network as well as Homemade Money by Richard Heede and staff of the Rocky Mountain Institute.

Additional information on home energy savings can be found in the Home Series: Home Tightening booklet available on the Iowa Energy Center’s Web site, www.energy.iastate.edu or by calling (515) 294-8819.

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