EXISTING HOMES
AIR SEALING
AS 1.0—Introduction
Material shall be installed according to the applicable codes and shall meet the requirements of the Existing Homes program. Air sealing is meant to increase comfort and energy efficiency of the home without sacrificing indoor air quality and health issues. All weatherization measures have the potential to tighten a home. Basements containing HVAC ducts or which have a direct access to the interior conditioned space of a home shall be considered conditioned space and should be considered in volume calculations. A house sealed below the Existing Homes Minimum Ventilation Level (MVL) will require mechanical ventilation, as described in the MV section of this manual. A mechanical ventilation strategy should be included as part of the scope of work if sealing below the MVL is possible.
The contractor shall provide the homeowner (and occupant) with Energy Trust’s Minimum Ventilation Level letter if an air leakage test determines the home is at or below MVL standards.
All significant accessible air sealing opportunities 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).
A functioning UL-listed carbon monoxide detector shall be installed according to manufacturer's specifications whenever combustion appliances are present in the home, garage or other attached space.
The air sealing incentive requires verification through diagnostic testing; a pre- and post-test CFM50 is required. Air sealing can be achieved through a number of processes, such as (but not limited to) sealing electrical, plumbing and ducting penetrations, chimney chases, dropped soffits, holes in the pressure boundary, and other such places where the air and thermal barriers are not aligned. Weatherstripping of exterior doors and sealing around interior window casings and baseboards can also reduce air leakage and air infiltration.
Air sealing on Existing Mobile Homes is only permitted if the trade ally is a participating contractor in the Existing Mobile Homes program. Contact Existing Mobile Homes for more information.
AS 1.1—Measurement
The air sealing incentive requires verification by performing an air leakage test using diagnostic testing equipment to depressurize the conditioned space of the home. A Blower Door test and manometer shall be used to perform the air leakage test, with the house set up in the following condition:
- Open all register dampers
- Close all exterior windows and doors
- Open all interior doors
- Close fireplace or wood stove dampers and doors
- Turn off all exhaust devices
- Turn down combustion water heaters (i.e., set to pilot)
- Set all HVAC system controls to off
- Set all ventilation controls to off
- Set up Blower Door; setting Channel A, pressure tap to measure house pressure with reference to the outside and Channel B, fan pressure with reference to the house
The air leakage test shall be performed before air sealing (pre-test) and after air sealing (post-test). Reductions in leakage shall be measured as follows:
Pre-Test CFM50 - Post-Test CFM50 = Total Leakage Reduction CFM50
Pre- and post- CFM50 data shall be recorded on the contractor's invoice, or on an attachment to the contractor's invoice, and submitted with the Existing Homes incentive application. Incentive application materials shall also include documentation of the areas where air sealing products were installed.
AS 1.2—Air Leakage Testing Replication Standard
When QC inspection is performed on an air sealing job, the QC post-test CFM50 shall be within 20% or 100 CFM50, which ever is greater, of the contractor's post-test CFM50 as recorded on the contractor's invoice.
Diagnostic equipment should be maintained and calibrated according to the manufacturer's requirements (see section IN 1.9).
AS 1.3—Installation
All materials shall be installed according to manufacturer's instructions and shall provide a strong, airtight, permanent, durable, safe and code-compliant seal. If insulation is being added, air sealing shall be performed to that area prior to installing insulation. Due diligence shall be applied to prioritize energy savings and reasonable effort made to address all accessible air sealing opportunities in order to attain a "complete measure." Operating the Blower Door while performing air sealing is recommended to monitor reduction and ensure building tightness does not fall below the MVL, unless the scope of work includes adequate mechanical ventilation.
See MV 1.2 section in this manual for calculating the minimum ventilation level required for a home.
Air sealing materials installed within 3" of heat-producing fixtures such as chimneys shall be fire-block rated. No foam product is fire-block rated.
Weatherstripping shall contact both surfaces and ensure gaps are adequately sealed. Weatherstripping shall not prevent easy operation of doors, latches or bolts.
AS 1.4—Minimum Ventilation Level
Calculating the MVL is required as part of a complete air sealing incentive. Mechanical ventilation is required when the ventilation potential is below the MVL (see MV 1.2).