Impact of Extreme Heat and Rising Temperatures on Urban Development

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WASHINGTON — The impact that rising temperatures and excessive heat waves are having on urban development, and strategies to mitigate urban heat island effects are explored in a new report, Scorched: Extreme Heat and Real Estate, published by the Urban Land Institute (ULI).

ULI is a global real estate organization with more than 44,000 members dedicated to responsible land use and the creation of sustainable, thriving communities.

Scorched, published with support from The JPB Foundation, explores how extreme heat is emerging as a growing risk factor and planning consideration across the United States, and how the real estate industry is responding with design approaches, technologies and new policies to mitigate the impacts and help protect human health. The real estate sector can improve resilience to extreme heat through mitigation strategies that reduce temperatures, as well as adaptation tactics to help people and businesses cope with extreme heat, it says.

Among the key take-aways in the report:

  • More cities in the United States are or will be at risk of extreme heat because of climate change and increased urban development.
  • Extreme heat is a pressing public health risk, particularly for low-income and elderly communities. Cool design strategies, combined with public health and emergency responses, can help offset heat-related mortalities.
  • Without intervention, the current and potential future impacts of extremely high temperatures — on real estate developments, infrastructure, and the economy — could be substantial.
  • Widespread adoption of mitigation strategies could help reduce the urban warming trends currently occurring in cities, leaving them to contend with a more manageable 1-degree to 2- degree Fahrenheit increase, rather than the 5-degree to 10-degree increase currently projected for some cities due to the urban heat island effect. (The urban heat island effect is the difference in temperature between urban and rural areas.)

It points to a broad range of options, many of which also add value as an amenity, including the use of light colored surfaces and materials, providing increased shade from built and natural canopies, and the use of “heat aware” building envelopes and heating, ventilation and air conditioning (HVAC) choices that stabilize indoor temperatures even during power outages.

“Real estate developers, designers and public policymakers are increasingly acknowledging the detrimental consequences of extreme heat and are seeking solutions to make buildings, neighborhoods, parks, and other outdoor spaces more adaptable to environmental conditions and comfortable for occupants,” said ULI Global Chief Executive Officer W. Edward Walter. “This presents an opportunity to reduce climate risk and create better communities in the process.”

Scorched provides a snapshot of the issue with several statistics documenting the impact of extreme heat as well as the significant potential of strategies to address it in the built environment:

  • $1 billion – the amount saved on electricity costs if all commercial buildings in the U.S. switched from dark to light roofs (source: Global Cool Cities Alliance)
  • 30 to 40 degrees Fahrenheit – the amount by which green roofs can be cooler than conventional rooftops (U.S. Environmental Protection Agency)
  • 2 years – The average payback time for installing a green roof on commercial buildings (General Services Administration)
  • 35 degrees Fahrenheit – The maximum amount that trees reduce surface temperatures — trees also reduce summer air temperatures from 2 degrees to 9 degrees Fahrenheit (Scientific American)
  • 10 percent – The decrease in office worker productivity in thermally uncomfortable and poorly ventilated environments (UK Green Building Council)

Investments in extreme heat mitigation technology and approaches can lead to a host of benefits, including an improved tenant experience, reduced operating costs, an improved likelihood of business continuity, enhanced branding, and additional foot traffic in pedestrian and retail environments, notes the report. For instance, being “heat-resilient” can potentially reduce the likelihood of construction delays caused by extreme heat; increase support from investors, public officials and other stakeholders; and reduce stress on public infrastructure. In addition, heat resilient projects can reinforce the developer’s reputation for high-quality, green design; and they can become heavily patronized places of refuge during extreme-heat events, leading to enhanced asset value, higher rent premiums and lower vacancy rates. In addition, the operating costs can decline due to less frequent replacement of heat-damaged materials, lower utility costs, and higher chance of sustained operations during extreme heat events.

Scorched highlights several case studies of developments that have successfully incorporated extreme heat mitigation strategies, including:

  • Bagby Street in Houston – a commercial corridor redeveloped with ample shade trees as well as rain gardens to help with flood mitigation
  • Edison Eastlake in Phoenix –a mixed-income development under construction that is designed to maximize shade, ventilation, and energy efficiency
  • National Landing in Crystal City, Virginia –the neighborhood that will house Amazon’s HQ2 will test the effectiveness of a reflective pavement sealant; and it will feature additional shade trees, green space and green roofs
  • Skysong in Scottsdale, Arizona – a mixed-use development designed with a heat-conscious building orientation, heat-efficient façade, natural and built shade, and energy efficient lighting and HVAC
  • Sundance Square Plaza in Fort Worth, Texas – a two-acre parking lot transformed into a plaza featuring elaborate shade umbrellas, shade trees, large water structures, and reflective building materials

“As extreme heat becomes increasingly prevalent because of the urban heat island effect and climate change, designing for heat and ensuring users’ comfort is likely to become a mainstream concern,” the report says. “This translates into different design and development decisions for buildings, which may need enhanced cooling capacity, and for public spaces and outdoor retail environments that are likely to be used differently in hot weather.”

The funding provided by The JPB Foundation for Scorched was contributed as part of a grant to the ULI Foundation, which provides philanthropic support for ULI initiatives to create thriving and sustainable communities worldwide.