Research Program Area: Health & Exposure
Topic Areas: Indoor Air Quality
Outdoor air supply rates and indoor air/pollutant transport between units have been a long standing problem in multifamily buildings. In medium and high-rise buildings, ventilation is often provided by vertical-stack exhaust ventilation systems, with make-up air coming from hallways and/or from the outdoors (through designed openings or leaks). The two major problems in these buildings have been: 1) significant exchange of air and pollutants between units; and 2) inadequate, time-varying ventilation rates of units. This study will investigate the impact of compartmentalization of multifamily units (e.g. apartments) on IAQ, energy usage and GHG emissions. Compartmentalization in this project means the process of air sealing all boundary walls of a multifamily unit (shared walls, floor, ceiling, and exterior walls). Unlike single-family homes, multifamily units have many shared walls with neighboring units. Reducing leakage between units can dramatically reduce smoke transfer, cooking odors, and even noise transfer. Units in three new multifamily buildings will be tested by measuring total air leakage and exhaust-flow variations across units. Two buildings will have some units receive different degrees of air sealing to produce three tightness levels, ranging from as-built to very tight (~0.15 cfm/ft2). Guarded blower-door air leakage testing will be conducted for a subset of units to distinguish outdoor air leakage from air leakage to neighboring units. For this project, air/pollutant transfer rates between units will be measured at different levels of compartmentalization using tracer-gas and PM2.5 sources. Airflow modeling will then be conducted to help generalize the field-test results. Modeling will be used to assess air exchange rates, inter-unit pollutant transfer, pollutant exposures, energy savings, and GHG reduction potential for different levels of compartmentalization in CA multifamily buildings. The modeling results will also be compared with field-test results for a subset of monitored apartments. These results will provide critical information to the CARB and the California Energy Commission (CEC) regarding the impacts of current and suggested future building standards on health protection, energy efficiency, and GHG emissions, in support of improving CA's Title 24 Building Energy Efficiency Standards (Energy Code).
For questions regarding this research project, including available data and progress status, contact: Research Division staff at (916) 445-0753
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