We seek to develop a cost effective method to meet the intent of the ETS prerequisite in residential projects that do not have gasketed doorways (required by USGBC-approved alternative methodology, but not commonly used in Pacific Northwest highrise residential design). The proposed alternative relies on a combination of three strategies to meet the Intent: construction methodology, tracer gas testing, and pressure differential testing, as follows. (1) Construction All units will be constructed to function as designated smoking rooms to effectively contain ETS: - All unit perimeter walls are contiguous, from structural slab to structural slab. All leakage paths are caulked and sealed. All demising walls are of double wall construction with no continuous pathway between units. Sheetrock is continuously sealed with a flexible caulk at the floor and ceiling. All electrical and telephone outlets in demising walls are smoke sealed. - No supply ductwork pathways between units. Ductwork pathways between units are limited to central exhausted airstreams with exhaust fans operated continuously on emergency power. (2) Tracer gas testing Testing procedure will be conducted on six units as follows: - Two corner units (NW and SE) on a lower floor; - One North exposure only unit on a lower floor; - Two corner units (NW and SE) on a higher floor; - One South exposure only unit on a higher floor. With predominant site wind direction being NW (summer) and ESE (winter), these locations provide optimum testing of the impact of wind forces and stack effect on ETS contamination. Test to be performed with residential windows closed. Specific measurement methods and locations follow ASHRAE 129-1997. The objective of the test is to demonstrate the effectiveness of passive or architectural measures at preventing ETS from migrating between units. (3) Pressure differential testing Tracer gas testing will include local differential pressure testing between the test condos and the corridors. Since the corridors are the most likely path for leakage of ETS between units, corridors will be maintained at positive pressure to prevent the leakage of ETS from condos into corridors. Tracer gas testing will demonstrate that migration of ETS between adjacent condos tested is essentially zero. This will be the result of a combination of the building design and construction described above and corridor pressure difference. We will then test an additional sampling of 10% of the building condos using pressure testing only as an effective surrogate for tracer gas testing. Testing Procedure 1. Verify the following conditions at the start of the test: a. Toilet exhaust fans running; b. Dryer exhaust fans running; c. Test and adjacent condo HVAC unit supply fans running and outlets are balanced; d. Corridor Makeup air unit is running and outlets are balanced; e. Corridor life safety pressurization dampers are closed; f. All corridors doors are closed on the test floor; g. Windows are closed in the selected test spaces and adjacent units; h. Wind speed outside is greater than zero; i. Outdoor air temperature difference with indoor spaces is greater than 50% of the design value. 2. Establish stable tracer gas concentration in the test space. Provide a concentration above the test value for a minimum of 15 minutes. 3. Measure concentration of tracer gas in the corridor outside the test space. 4. Measure concentration of tracer gas in the spaces adjacent to the test space. 5. Measure pressure differential between tested condo test space and corridor. 5. Repeat for additional test spaces. CRITERIA FOR PASSING Building passes if tests show that concentration in the corridor and adjacent spaces is below one percent of the lowest stable established value maintained in the test space.
The proposed approach is not acceptable. The project team has proposed a hybrid approach, in an effort to meet the intent of the prerequisite, claiming to reduce costs associated with tracer gas testing for 10% of the units. The 12/3/03 credit ruling that provides for blower door testing resulted from a combined effort by the LEED IEQ Technical Advisory Group, national IAQ experts and users to find a more economical approach for residential projects to achieve this prerequisite. In the course of this study, the team found that the blower door test method was not only less expensive for projects, but was also readily available across the country in contrast to the tracer gas test method. The proposed approach attempts to combine methodologies approved in previous CIR rulings for both tracer gas and blower door testing procedures and reduces the quantity of units required to be tested under each procedure. The sampling sizes and testing methods approved in previous CIR rulings (dated 1/18/02 and 12/3/03) were established to provide a consistent approach that can be applied to multi-family residential projects, regardless of building type, climatic conditions or configuration. As this proposed sampling strategy applies to the building size and configuration of this particular project, but cannot be applied consistently to other multi-family residential projects with different conditions and configurations, it is not approved as an alternative approach. If customized hybrid approaches to this credit were allowed, the door would be open for all projects to propose different methods to achieve compliance. It is impossible for the USGBC to assess individual approaches for this credit on a project-by-project basis.