The Issue

Healthy Zero Energy Buildings (HZEB)

Previous studies have shown that low ventilation rates are associated with reduced performance by workers and students. Low ventilation rates, which can lead to inadequate removal of indoor-generated air contaminants, have also been associated with negative impacts on human health. In contrast, provision of ventilation rates above current guideline levels has been associated with reduced absenteeism in schools and offices.

Outside air ventilation is the principal mechanism by which indoor-generated air pollutants are removed from our buildings; however, ventilation comes with a significant energy cost. Currently, heating, cooling and ventilating commercial buildings represents 29% of their total on-site energy use, with roughly one-third of this energy used to heat and cool ventilation air. As we aim to make buildings more energy efficient through programs such as California’s Zero Energy Buildings mandate, it is expected that energy consumption for building ventilation will become one of the limiting factor in achieving energy reduction goals.

To date, ventilation standards have not explicitly considered the health impacts of indoor contaminants. Current standards are not based on established environmental health risk assessment methods used in setting exposure standards. Inadequately based ventilation standards can lead to either under-ventilation of spaces, which reduces indoor air quality (IAQ), or conversely to over-ventilation, which wastes energy. In order to develop the health-based ventilation standards needed to build the energy efficient buildings of the future safely, it is important to first understand how much ventilation is needed to provide healthy, productive environments.