Article #1530 - Are Duct Sealing Requirements in Codes Working?
It sounds simple, doesn''t it? Constructing airtight conduits known as ducts through which air passes to be distributed to the different rooms within a house, apartment, or condo. However, study after study shows that ducts in new buildings are not only not airtight, but often have major leaks. For buildings with ducts passing through spaces outside the thermal envelope--like attics or garages--building scientists typically estimate average losses in the neighborhood of 25% of the total energy. Once new buildings are completed, air will be pumped through these ducts for many hours during most days of the year for decades. The total cost of energy passing through these ducts over their lifetimes will typically be in the tens of thousands of dollars. Clearly, improving the air-tightness of duct installations makes economic sense and has the potential to improve occupant comfort and air quality.
While the energy codes require that ducts be properly sealed, traditional visual inspections--looking for what are often tiny cracks and leaks--are time consuming and problematic. The ducts are often in difficult-to-access areas such as attics and crawlspaces, and leaks often are not obvious or not even visible at all. Most building scientists agree that the only sure way to check for duct leaks is to perform a pressurization test on the ducts.
Adding pressurization tests to code requirements would give teeth to the existing air-sealing requirements, guaranteeing homeowners the level of efficiency and comfort they expect from their code-compliant homes. The tests could be done in a matter of minutes using widely available "duct blaster" equipment. Is it time for energy codes to address this serious problem head on?
The DOE Building Energy Codes Program is interested in your thoughts on this topic. To let us know what you think, complete the survey at
energycode.pnl.gov/EnergySurvey/entry.jsp?id=1135271249041