This CIR concerns handling of HVAC openings during the blower door test for LEED-NC v2.2, EQ prerequisite 2, Environmental Tobacco Smoke Control. To satisfy EQp2, residential buildings which will allow occupants to smoke in residential units may meet the set of requirements under Option 3. This requires demonstration of acceptable sealing by conducting a blower door test in accordance with ASTM-E779-03 on a sample of the residential units. The units must demonstrate less than 1.25 square inches of leakage area per 100 SF of enclosure area. Leakage area is calculated in accordance with the referenced Standard and represents the total cumulative open area in the enclosure surfaces that define the test unit\'s boundary. The test procedure described in ASTM-E779-03 includes the stipulation that, "HVAC balancing dampers and registers should not be adjusted. Fireplace and other operable dampers should be closed unless they are used to pass air to pressurize or de-pressurize the building." (See Para. 8.2) Regardless of the reasoning behind it, this stipulation presents a problem when the test results are to be measured against a fixed maximum leakage area as in this case. In many instances the open area of HVAC openings alone may exceed the allowable leakage area for a unit, rendering this requirement impossible to meet. For example, a 600 SF apartment with 2050 SF of enclosure area would have a maximum allowable leakage area of 25.6 square inches. If this unit has a 6" square exhaust grille (such as might be required for the toilet exhaust) the open area of this alone would exceed the allowable 26 square inches of leakage area. We propose to meet this requirement by conducting the necessary blower door tests in accordance with ASTM-E779-03, with the sole exception that HVAC openings are closed or sealed during the test similar to fireplace dampers. Please confirm this interpretation or provide an alternative which would address this issue.
The project team is requesting an exception to ASTM-E779-03, Section 8.2, with regards to HVAC openings, so that they can be closed or sealed. ASTM-E779-03 is explicit in stating that "HVAC balancing dampers and registers should not be adjusted", and also that "Fireplace and other operable dampers should be closed unless they are used to pass air to pressurize or de-pressurize the building." The practice for outdoor air leakage measurements, which is the intent of this standard, is to test the building without sealing over openings to outdoors. If the openings have dampers that can be closed (e.g. fireplace) then they are closed. For projects to meet the intent of this credit all openings to outdoors (kitchen and bathroom exhausts, z-duct outdoor air transfer grilles, mechanical system outdoor air intakes) should be sealed; forced air unit supply and return ducts should not be sealed and the system should be off. To clarify the method of conducting the test and determining the leakage area, the test method involves pressurization and de-pressurization of the building and measurements of the resulting airflow rates at the given indoor/outdoor pressure differences. The air leakage characteristics (including the leakage area) of the building envelope are determined based on the relationship between airflow rates and the pressure differences. These readings are taken at a range of induced pressures, with all other items being constant ¬ and the average of the before/after zero flow envelope pressures is subtracted from the measured envelope pressures at each instance to determine the corrected envelope pressures (per 9.3 of ASTM-E779-03). Applicable Internationally.