Extreme Heat and Urban Heat Island Code Overlay

Guideline / March 20, 2024 / Codes And Policy

The Extreme Heat and Urban Heat Island Code Overlay provides code language for jurisdictions interested in acting against extreme heat and mitigating the urban heat island (UHI) effect.

The Code Overlay strengthens and expands on cool surface requirements in model energy codes and standards. These expansions include ASHRAE 90.1-2022, the International Green Construction Code (IgCC) 2021, and the 2021 International Energy Conservation Code.


In addition to cool surface language, the code overlay adds maximum temperature setpoints in the:

  • 2021 International Mechanical Code
  • 2021 International Residential Code (IRC)
  • 2024 International Building Code (IBC)

This language mirrors the minimum temperature setpoints that exist in these codes.

While the report is written as a code overlay, jurisdictions can modify the language and implement it in an ordinance, zoning code, incentive program, or other policy that best fits their needs.

We have provided a comprehensive PDF document via the download button above.

Email us at [email protected] to request the code provisions in a Word document.


Additional Resources

Policy Actions to Tackle Extreme Heat and Urban Heat Islands

This factsheet briefly summarizes the extreme heat and urban heat island (UHI) mitigation strategies covered above in NBI’s Extreme Heat and Urban Heat Island Code Overlay. Strategies include cool roofs and walls, cool/permeable pavement, trees and vegetation, and maximum indoor temperature setpoints. The factsheet also describes the various policy pathways that jurisdictions can take to implement extreme heat/UHI mitigation strategies, such as energy, green, or building codes, zoning codes, ordinances, and programs. In addition, the factsheet includes talking points for jurisdictions and community members to help advocate for solutions, along with examples of jurisdictions that have implemented the UHI/extreme heat policy solutions.

Download the factsheet: Policy Actions to Tackle Extreme Heat and Urban Heat Islands (PDF)