1. Urban Heat Islands and Mitigation Strategies
LIHEAP Webinar
May 25, 2016
Victoria Ludwig, U.S. EPA Heat Island Reduction Program

2. What is the Heat Island Effect?
Micro-scale temperature differences between urban and rural areas
Urban areas can be 2 – 22 º F higher than rural areas
Air and surface temperatures
Day and night temperatures
Complex due to….
Surface vs. air temperature
Diurnal and seasonal variability
Dependent on synoptic conditions
Geographic vs. topographic causation
Importance of other weather variables (humidity, etc)

3. What Causes the Heat Island to Form?
Reduced vegetation
Materials used to build urban infrastructure
Urban geometry
Generation of waste heat (e.g., air conditioners, engines)

4. Climate Change and Heat Islands
Nationwide, unusually hot summer days (highs) have become more common over the last few decades
The occurrence of unusually hot summer nights (lows) has increased at an even faster rate. This trend indicates less “cooling off” at night
Climate models project increases in the frequency, intensity, and duration of extreme heat events in the decades ahead
Heat islands amplify extreme heat events

5. Heat Island Impacts Increased energy use
5 – 10 % of summertime electricity demand cools heat islands
1.5 – 2.0% E demand  for every 1 ºF  in the summer
Longer peak periods; pressure on E grid; brownouts, blackouts
Air quality and carbon pollution
Increased greenhouse emissions (climate change)
Increased air pollution
Increased ground-level ozone formation
Water quality
Warmer water runoff = ecological shock in waterways
Increased water runoff = more pollutants in waterways 5 5

6. Extreme Heat and Public Health
Heat is a serious danger:
Respiratory problems
Heat cramps, heat exhaustion
Non-fatal heat stroke/sun stroke
Heat-related mortality
Extreme heat is often the most deadly weather-related event in a given year (compared to hurricanes, lightning, tornadoes, earthquakes, etc.).
Overall, nearly 8,000 Americans suffered heat-related deaths since 1979
Peaked in 2006, a year that was the second-hottest year on record in the U.S.
Extreme heat contributed to the deaths of about 8,000 people since 1979
Older adults and young children are physiologically sensitive to extreme heat.
People living in poverty are vulnerable due to substandard housing and lack of access to air-conditioning. Note that 8.7% of the U.S. population of older adults lived below the official poverty level in 2011. 6

7. Who is the Most Vulnerable?
Reducing heat islands helps protect public health…now and in the future
Lower temperatures provide direct benefits to vulnerable populations:
Older adults,
Young children,
People with lower incomes
Outdoor workers
People with compromised health
Indirect health benefits include better air quality due to reduced ozone formation
More than 9% of U.S. children and nearly 8% of older adults aged currently have asthma. Exposure to ozone can exacerbate asthma. 7

8. Urban Design Can Reduce Vulnerability
Incorporating heat island mitigation measures in built environment considerations offers an opportunity to improve public health AND MORE:
Trees and Vegetation: Better air quality, carbon storage
Green Roofs: Stormwater benefits, improved human comfort
Cool Roofs: Increased grid reliability, energy savings
Cool Pavements: Lower air temperatures, public safety benefits
Smart Growth: More vegetation, less paved areas
Infrastructure projects often have long lifetimes; if their design can be influenced today to incorporate heat island mitigation measures, they’ll provide health and other benefits for years to come.
ACEEE (American council for an energy-efficient economy) and GCCA survey of 26 cities in North America (Vancouver and Toronto) found that each city had at least one mitigation strategy and 25 had more than one. Most popular is tree canopy.

9. Mitigation Strategy: Trees & Vegetation
Most U.S. communities have opportunities to increase the use of trees and vegetation in their land cover to reap multiple benefits.
Strategically planting trees maximizes energy savings.
Buildings
Parking lots
Streets

10. Mitigation Strategy: Green Roofs
Decrease heat island impacts by shading roof surfaces and through evapotranspiration
Can save energy both in the summer and winter; energy savings depend on local conditions and building circumstances
Can be installed on a wide range of buildings, from industrial facilities to private residences

11. Mitigation Strategy: Cool Roofs
Cool roofing products are made of highly reflective materials that can remain about 50 to 60°F cooler than traditional materials during peak summer weather.

12. Implementation through Voluntary Efforts
Demonstration Projects
Incentive Programs
Urban Forestry and Community Tree Planting Programs
Weatherization
Outreach and Education
Awards

13. Implementation through Policy Efforts
Procurement
Resolutions
Tree and Landscape Ordinances
Comprehensive Plans and Design Guidelines
Zoning Codes
Green Building Programs and Standards
Building Codes
Air Quality Requirements

14. Opportunities and Strategies to Consider
Work with utilities and public utility commissions
Collaborate with state and local government environmental agencies
Promote energy savings benefits to developers and landlords
Develop education materials in cooperation with community action groups
Talk with other state governments that have implemented heat island reduction strategies

15. EPA’s Heat Island Program

16. Program Overview Mission
The EPA Heat Island Reduction Program works to increase the number of programs and policies that include heat island reduction measures to create comfortable and sustainable communities.
Heat Island Community
Local and state policymakers/program designers
Academia/researchers
Other federal agencies
Non-profit organizations
Industry 16

17. Heat Island Program Resources
Website: Basic information on heat island topics, calendar of events, heat island newsroom, science corner and more
Examples: Database of info on more than 75 local and state initiatives to reduce heat islands and achieve related benefits
Compendium of Strategies: Reducing Urban Heat Islands, provides scientific background, mitigation strategies, case studies, and links to other resources
Heat Island Basics
Trees and Vegetation
Green Roofs
Webcasts: Cover topics such as local/regional urban heat island case studies, new scientific findings, and specific mitigation strategies
Newsletter
Cool Roofs
Cool Pavements
Heat Island Reduction Activities

18. Heat Island Newsletter Sign-Up:
Contact Information
Victoria Ludwig
U.S. Environmental Protection Agency
State and Local Climate and Energy Program
Website:
Heat Island Newsletter Sign-Up: