DU 1.0—Introduction
Supply and return ducts and plenums shall be insulated. Sheet metal ducts and plenums shall be insulated with R-11, or greater, insulation batts. Flexible duct shall be R-8, or greater. Special attention shall be paid to elbows and termination areas to ensure complete coverage. Basements containing HVAC ducts or which have a direct access to the interior conditioned space of a home. Insulation installed on ducts in conditioned space will not be eligible for Energy Trust incentives. To qualify for an Existing Homes incentive, existing insulation condition must be R-2 or less and ducts must be insulated to R-11 or greater.
All accessible ducts, regardless of eligibility for incentives, must meet the applicable requirements to be considered a complete measure, unless a requirement is waived by Existing Homes or physical barriers exist (see section IN 1.5). Areas where existing insulation is greater than R-2 are not eligible for incentives. However, areas where existing insulation is greater than R-2 must meet all applicable specifications so that areas where existing insulation is less than R-2 may qualify for an incentive.
DU 1.1—Prescriptive Duct Sealing
Before insulating ducts, all physically accessible ducts in unconditioned areas must be sealed according to specifications in Sections DS 1.3 – DS 1.6. Combustion Appliance Zone testing shall be performed according to specifications in Section DS 1.7. Carbon monoxide detectors shall be installed according to specifications in Section DS 1.8.
Duct sealing may be eligible for a waiver when duct leakage to outside (measured in CFM50) is less than
10 percent of the square footage of the conditioned space of the home. Contact the trade ally coordinator at existinghomesta@energytrust.org or call 1.866.365.3526 option 9 for a waiver.
DU 1.2—Insulating Ductwork
All ducts in unconditioned areas shall be insulated. Duct insulation installed in basements, garages, storage areas or other Human Contact Areas shall be covered to limit occupant exposure to insulation fibers. Covering shall meet applicable fire codes. Do not insulate flex ducts or preformed fiberglass duct board. Insulation shall be secured to ductwork every 12 inches with twine, noncorrosive wire or vinyl tape.
DU 1.3—Supporting/Repairing Ducts
Ducts shall comply with the requirements of DS 1.4 for support and repair specifications.