Research

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EPA's Heat Island Reduction Initiative (HIRI) focuses on translating research results into outreach materials, tools, and guidance to provide communities with information needed to develop heat island projects, programs, and policies.

This page highlights one related research effort that EPA is supporting and describes several existing studies aimed at better understanding the impacts that heat island reduction strategies have on urban meteorology, air quality, energy demand, and human health.

What Current Heat Island Research is EPA Supporting?

Through HIRI, the EPA is supporting research on the impact that cool pavement materials have on urban heat islands and energy consumption. EPA worked with Arizona State University (ASU) to launch the National Center of Excellence on SMART Innovations for Urban Climate and Energy on April 24, 2006. The Center of Excellence will develop the next generation of sustainable materials and renewable technology (SMART) innovations that can help reduce urban temperatures and the resulting effect on energy consumption in U.S. cities. It will bring together leading researchers, government officials, and industry representatives to find solutions that have a sound scientific, economic, and practical basis. For more information, see the National Center of Excellence on SMART Innovations for Urban Climate and Energy.

What Meteorological and Air Quality Research Has HIRI Supported?

HIRI's past support of meteorological and air quality modeling research has resulted in several key initiatives:

Urban Heat Island Pilot Project (UHIPP)

Measuring the reflectance of a cool roof in Salt Lake City, UT.

HIRI supported research on the impacts of heat island reduction strategies on local meteorology and air quality in five UHIPP cities: Baton Rouge, Salt Lake City, Sacramento, Chicago, and Houston. Using meteorological, building energy, and air quality models, researchers determined that heat island reduction strategies can reduce air temperatures, ground-level ozone concentrations, and energy consumption. See the Pilot Project pages for more information.

Research in Northeastern Cities

HIRI conducted studies to determine the impacts of heat island reduction measures on meteorology and air quality in northeastern cities with long-standing ground-level ozone problems.

Interactions between meteorology, pollutants, ground-level ozone formation, and transport are complex, and results from this study indicate that heat island reduction strategies may have mixed effects on ozone in these cities. See the report (PDF, 19pp., 36 KB).

Homology Mapping

HIRI supported a study to select U.S. cities that are "prototypical" and could be used to represent other cities to extend the utility of modeling results. Based on geographical, land-use, emissions, and population characteristics that are important for meteorological and air quality modeling, this "homology mapping" technique would allow cities that have not been modeled to apply results from a similar, modeled area to determine if heat island reduction strategies can improve air quality in their area. See the report (PDF, 28pp., 88 KB).
Meteorological Modeling in Eight Regions

HIRI supported research on the impacts of heat island reduction strategies on local meteorology using the MM5 mesoscale meteorological model. Researchers identified eight regions that include over 20 cities. These "domains" cover:
- California: Los Angeles-Bakersfield-Fresno, San Joaquin Valley, Sacramento, San Francisco East Bay, Visalia-Tulare-Porterville, San Diego, and Merced.
- Texas: Dallas-Ft. Worth and Tyler. · Michigan: Grand Rapids and Detroit.
- Arizona: Phoenix and Tucson.
- Mid-Atlantic: Washington, Baltimore, and Philadelphia.
- Southeast: Charlotte and Atlanta.
- South: Louisville and Knoxville.
- Louisiana: Baton Rouge and New Orleans.
These areas were selected because: (a) they had air quality and ozone problems based on one-hour and eight-hour ground-level ozone data, (b) they represented diverse locations to compare heat island reduction effects, and (c) representatives from these cities had expressed interest in introducing heat island reduction measures. See the final report, written by Portland State University.

Additional air quality analyses were conducted for a subset of these cities.

What Has EPA Done to Include Heat Island Mitigation Strategies in Air Quality Planning?

EPA has developed a policy guidance on bundled measures (PDF, 55 pp., 3.05MB) that describes how states can aggregate, or "bundle" multiple smaller emission reduction measures together in their State Implementation Plan (SIP). If a state and local governments can demonstrate to EPA that heat island reduction measures will improve air quality in their area, one or more these strategies can be included in their bundle. The benefit of "bundling" is that the responsible agency does not need to demonstrate that each measure performs as predicted, rather that the whole bundle does.

EPA has also published guidance on non-traditional air quality improvement measures of which heat island reduction strategies are considered. See: "Incorporating Emerging and Voluntary Measures in a State Implementation Plan (SIP)." (PDF, 30pp., 63 KB)

What Heat-Related Health Research Has HIRI Supported?

To better understand how heat affects public health and the extent to which reducing temperatures can save lives, HIRI worked with the University of Delaware to determine the potential for heat island reduction to alleviate heat-related mortality in select U.S. cities.

The University of Delaware's Synoptic Climatology Group developed a method for identifying oppressive air masses in urban areas that are historically associated with elevated mortality. Tulane University and LBNL provided information on the impacts various heat island reduction scenarios have on meteorology in these cities, using MM5. The results were fed into the University of Delaware's heat-related mortality model to see if the following occur: the number of oppressive air mass days was decreased; the severity of the remaining oppressive days was diminished; or there was a marked reduction in estimated heat-related mortality. See the final reports .

How Is HIRI Turning Research into Action?

Through a cooperative agreement with HIRI, ICLEI—Local Governments for Sustainability has been developing and distributing information to local governments on heat island reduction strategies. ICLEI has developed a policy package that contains:

Fact sheets on urban heat island reduction;
A sample resolution to adopt urban heat island reduction policies affecting both local government and private sector operations;
A reduction policy framework that provides information necessary to construct a heat island reduction policy;
Model ordinance language to help practitioners modify development standards and planning, landscape, and building codes; and
Other resources including links to product lists, scientific studies, and successful programs.

In October 2001, ICLEI initiated the Urban Heat Island Mitigation Policy Adoption and Peer Exchange Initiative. ICLEI and HIRI selected five cities to participate: San Jose, CA; Tucson, AZ; Philadelphia, PA; Atlanta, GA; and Louisville, KY. Each city has committed to developing, adopting, and implementing reduction strategies within their jurisdictions.

ICLEI, HIRI, and national experts provide customized technical assistance to participating cities. ICLEI hosted the first of two workshops for participants on December 6, 2001 in Chicago. The second workshop occurred in Toronto, Ontario, Canada in May 2002 during the North American Urban Heat Island Summit .

What Is EPA Doing to Include Heat Island Mitigation Strategies in Air Quality Planning?

EPA has developed policy guidance describing how states can"bundle" multiple smaller emission reduction measures together in their State Implementation Plan (SIP). If a state and local governments can demonstrate to EPA that heat island reduction measures will improve air quality in their area, one or more these strategies can be included in their bundle. The benefit of "bundling" is that the responsible agency does not need to demonstrate that each measure performs as predicted, rather that the whole bundle does. Also see: "Incorporating Emerging and Voluntary Measures in a State Implementation Plan (SIP)." (PDF, 30pp., 63 KB)