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Principle Investigator: Francis J. Offermann PE CIH
Indoor Environmental Engineering
Sponsors: California Air Resources Board
California Energy Commission

The primary goal of this study is to obtain information on ventilation characteristics and indoor air quality (IAQ) in new single-family detached homes in California through a field study.

Concerns have been raised regarding whether households in new California homes use windows, doors, exhaust fans, and other mechanical ventilation devices enough to remove indoor air pollutants and excess moisture. Various building materials, heating and cooking appliances, and other products used in new homes can emit substantial amounts of formaldehyde, other toxic air contaminants, combustion pollutants, and/or water vapor. Building practices and building standards for energy efficiency have led to more tightly-sealed homes that rely on occupants to open windows for ventilation. However, there is very little information on current ventilation practices, IAQ, or indoor pollutant sources in new California homes.

Project Summary

We will study 108 new, single family homes from two climatic regions of the state, including a subset of 20 homes with mechanical fresh-air ventilation systems. We will measure and record ventilation characteristics, including window opening and closing, indoor pollutant concentrations, residents’ ventilation practices, residents’ IAQ perceptions, and residents’ decision factors for ventilation and IAQ-related actions. Measurements of indoor and outdoor air quality and ventilation parameters will be made in the summer and winter. Indoor air levels of volatile organic compounds, aldehydes, PM2.5, and nitrogen dioxide will be measured over one day. Home ventilation will be determined through tracer gas measurements, building leakage measurements, window use measurement, air flow measurements of fan systems, and occupant diaries. Some homes will have additional measurements, including Spring or Fall measurements, multiple-day sampling (especially for weekday-weekend differences), and formaldehyde sampling in the attic and heating, ventilating, and air-conditioning (HVAC) systems.

This project has the following specific objectives:

1. Determine how residents use windows, doors, and mechanical ventilation devices, such as exhaust fans and central heating and air-conditioning systems.

2. Measure and characterize indoor air quality (IAQ), ventilation, and the potential sources of indoor pollutants.

3. Determine occupant perceptions of, and satisfaction with, the IAQ in their homes.

4. Examine the relationships among home ventilation characteristics, measured and perceived IAQ, and house and household characteristics.

5. Identify the incentives and barriers that influence occupants use of windows, doors, and mechanical ventilation devices for adequate air exchange.

6. Identify the incentives and barriers related to people’s purchases and practices that improve IAQ, such as the use of low-emitting building materials and improved air filters.

This study will provide, for the first time, representative, accurate and current information on both ventilation and IAQ in new California homes. IAQ and household ventilation practices will be obtained from multiple seasons and regions of the state, which will help characterize the full range of indoor pollutant exposure in such homes. Measured levels of ventilation and IAQ will be compared to current guidelines and standards. Information on the use of windows, fans, and central systems will help establish realistic values for developing state standards for building energy efficiency.

The Commission will use the study results as a scientific basis to revise the state’s building energy efficiency standards in order to provide more healthful, energy-efficient homes in California. The study results will improve ARB’s ability to identify current sources of indoor air pollutants, to assess Californians current exposure to measured toxic air contaminants, and to recommend effective strategies for reducing indoor air pollution.

Current Status

Indoor Environmental Engineering was awarded this project in June, 2005 and has completed the Summer (July-August, 2006), Fall (October, 2006), and Winter (January-February, 2007) field monitoring sessions in 54 Northern and 54 Southern California homes. The project Final Report is expected to be completed in April, 2008. The report containing the results of the ventialtion rate and formaldehyde concentration measurments for the Summer field session session is now available. (Download Summer Field Session Report)

Quiet air sampler developed specifically for the Ventilation and Indoor Air Quality in New California Homes study. Collects integrated 24 hour samples of particles, nitrogen dioxide, volatile organic compounds, including formaldehyde, as well as real time measurements of carbon dioxide, carbon monoxide, relative humidity, and temperature.