Ductwork Air Leaks Account For
As Much As 20% of Your Electric Bill
Duct Leaks Increase Cost by 20%
Studies conducted throughout the country have found that duct leakage contributes 10% to 30% of heating and cooling loads in many homes. In addition, duct leakage can decrease comfort and endanger health and safety. In a typical house, however, about 20 percent of the air that moves through the duct system is lost due to leaks, holes, and poorly connected ducts. The result is higher utility bills and difficulty keeping the house comfortable no matter how the thermostat is set.
The Problem of Duct Leakage
Leaky Return Ducts
Chart shows the impact of return and supply air leaks on HVAC equipment efficiency when the return air is drawn from a hot attic. For example, a HVAC system having 15% return leakage in a moderately hot attic (125°F) can suffer a 50% drop in efficiency – from SEER 10 to SEER 6.
When HVAC supply ducts leak air to outside, the return side of the system still requires the full amount of air back. In a home with 15% supply leaks, if 100% of the replacement air comes from the attic at 125 degrees, the efficiency of the system will drop from SEER 13 to about SEER 8.0, a 40% reduction in efficiency. Note that duct leak age of only 5% results in efficiency losses of 5% to 15%.