Center for Earth Systems Engineering and Management

As the number of heat waves are expected to increase significantly into the future in the U.S. Southwest, new insight is needed into how urban infrastructure can be repositioned to protect people. In the Phoenix metro area infrastructure have largely been deployed over the past half century, during a time when climate change was not a concern. Now, as the county struggles to protect people from heat, there is a need to reassess how existing and new infrastructure can be positioned to reduce health impacts while improving sustainability. Using a neighborhood in Mesa, Arizona as a case study, we assess how changes to transportation infrastructure, building infrastructure, and landscaping can reduce heat exposure. A number of strategies are considered including the optimal deployment of heat refuges, deploying less convective surface materials, and deploying more thermally preferable building materials. The suite of strategies could be considered by cities throughout the Phoenix metro area.

The leading source of weather-related deaths in the United States is heat, and future projections show that the frequency, duration, and intensity of heat events will increase in the Southwest. Presently, there is a dearth of knowledge about how infrastructure may perform during heat waves or could contribute to social vulnerability. To understand how buildings perform in heat and potentially stress people, indoor air temperature changes when air conditioning is inaccessible are modeled for building archetypes in Los Angeles, California, and Phoenix, Arizona, when air conditioning is inaccessible is estimated.

An energy simulation model is used to estimate how quickly indoor air temperature changes when building archetypes are exposed to extreme heat. Building age and geometry (which together determine the building envelope material composition) are found to be the strongest indicators of thermal envelope performance. Older neighborhoods in Los Angeles and Phoenix (often more centrally located in the metropolitan areas) are found to contain the buildings whose interiors warm the fastest, raising particular concern because these regions are also forecast to experience temperature increases. To combat infrastructure vulnerability and provide heat refuge for residents, incentives should be adopted to strategically retrofit buildings where both socially vulnerable populations reside and increasing temperatures are forecast.