Informing decision-making about indoor heat risks to human health.
Status: Current
Funding Sources: California Department of Housing and Community Development
Project Objective
The purpose of this work is to identify maximum safe indoor air temperatures for California residential dwelling units, and also strategies for maintaining indoor temperatures within these limits. This work will provide guidance to support the California Department of Housing and Community Development (HCD) in its development of statewide policy recommendations.
Significance to Industry
Heat is the leading weather-related cause of death in the United States and heatwaves are increasing in frequency, duration, and intensity across the country. California residential building standards, based on international and uniform model codes, have long specified that residential dwelling units must be able to maintain a minimum indoor temperature of 68° Fahrenheit (20° Celsius), yet there is no requirement with respect to a maximum indoor air temperature. While there is considerable literature on the effects of heat on health, there is no clear consensus on a maximum safe indoor air temperature. In addition, significant economic and environmental costs may be associated with keeping homes cool, particularly when done with mechanical air conditioning. The primary tradeoffs that should be considered when establishing a maximum safe indoor air temperature for California residential dwelling units include human health, economic, and environmental impacts.
Per Section 31 of California Assembly Bill 209, the California Department of Housing and Community Development (HCD) has been tasked with developing policy recommendations to the California Legislature to ensure that residential dwellings can maintain a safe maximum indoor temperature. The Center for the Built Environment (CBE) is conducting research and stakeholder meetings to support HCD in developing these recommendations.
Research Approach
CBE’s research team is using multiple approaches to inform this important policy issue. We are performing a critical literature review on the relationship between residential thermal conditions and human health. We are also conducting building performance modeling and simulation studies to characterize the costs and performance associated with meeting a broad range of possible upper temperature limits for new and existing single and multifamily dwellings in all California climate zones. We will also conduct a review of climate forecasts, and investigating whether HVAC climate design data should be updated to reflect the latest forecasts.
We are also participating in stakeholder meetings to present the work as it evolves and to gather input. We plan to organize a workshop with heat stress physiology experts from around the world, including many current collaborators, to evaluate our proposals. We will also investigate and propose mechanisms to collect thermostat data to monitor indoor temperatures in California dwellings for ongoing research and assessment in the state.
Using information from critical literature reviews, results from this research effort and stakeholder input, we will create a policy proposal document. Finally, we will develop guidelines to help Californians keep cool in their residences during climatic heat events, publish these in the form of a website, and conduct outreach to draw attention from relevant stakeholders. We will also implement the final AB209 policy into the free online CBE Thermal Comfort Tool.