DALLAS URBAN HEAT ISLAND - Vision North ... The Dallas Urban Heat Island Study examines how and where

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  • DALLAS URBAN HEAT ISLAND DALLAS SUSTAINABLE SKYLINES INITIATIVE

    Prepared by:

    Houston Advanced Research Center Prepared for

    U.S. Environmental Protection Agency

    March 2009

  • THE SUSTAINABLE SKYLINES INITIATIVE The Sustainable Skylines initiative is a three-year partnership between the City of Dallas, the U.S. Environmental Protection Agency, and the North Central Texas Council of Governments to promote sustainability within the City via voluntary programs which emphasize air quality improvements. The Sustainable Skylines Initiative (SSI) at EPA provides a framework that, when implemented in an area, can achieve measurable emissions reductions and promote sustainability in urban environments. Under the SSI, an area can choose to perform projects from seven categories: central city livability, stationary and area sources, energy and climate change, land use transportation strategies, diesel engines emission reduction, green building and green building development, and off-road/non-road sources (emission reductions).

    HOUSTON ADVANCED RESEARCH CENTER 4800 Research Forest Drive • The Woodlands, Texas 77381 • http://www.harc.edu HARC is a 501(c)(3) not-for-profit organization based in The Woodlands, Texas dedicated to improving human and ecosystem well-being through the application of sustainability science and principles of sustainable development. HARC's mission is to move knowledge to action to improve human well-being and the environment.

  • TABLE OF CONTENTS Dallas Urban Heat Island Overview................................................................................................................................1 The Dallas Urban Heat Island................................................................................................................................1 Reducing Dallas Urban Heat Island Effects...........................................................................................................6 Conclusions ...........................................................................................................................................................8 Options for Urban Heat Island Mitigation ...............................................................................................................8 Trees and the Dallas Urban Heat Island ......................................................................................................................10 Executive Summary .............................................................................................................................................10 Options for Dallas Trees: Summary.....................................................................................................................11 Introduction ..........................................................................................................................................................14 A. Tree Costs and Benefits .................................................................................................................................15 B. Planting for Heat Island Reduction .................................................................................................................19 C. Options for Trees and the Urban Canopy ......................................................................................................30 1. Setting Goals..........................................................................................................................................30 2. Consolidate Outreach and Education ....................................................................................................31 3. Obtaining Urban Forest Management Data ...........................................................................................33 4. Funding for Tree Planting and Conservation .........................................................................................35 5. Incentives and Regulations ....................................................................................................................36 Cool Roofing and the Dallas Urban Heat Island...........................................................................................................42 Executive Summary .............................................................................................................................................42 Options for Cool Roofing Actions: Summary ......................................................................................................43 Introduction ..........................................................................................................................................................44 A. Thermal Effects of Roofing .............................................................................................................................45 B. Cool Roofing Costs and Benefits ...................................................................................................................46 C. Cool Roof Technologies .................................................................................................................................49 D. Options for Cool Roof Actions ........................................................................................................................50 1. Increasing Awareness Through Outreach..............................................................................................51 2. Policies to Encourage Cool Roofs..........................................................................................................53 3. Incentives and Regulations ....................................................................................................................54 Cool Pavements and the Dallas Urban Heat Island .....................................................................................................56 Executive Summary .............................................................................................................................................56 Dallas Cool Paving Strategies and Actions: Summary ........................................................................................57 Options for Cool Paving Actions: Summary.........................................................................................................58 Introduction ..........................................................................................................................................................59 A. Thermal Effects of Paved Surfaces ................................................................................................................60 B. Costs and Benefits of Cool Pavements ..........................................................................................................62 C. Cool Pavement Technologies ........................................................................................................................70 D. Cool Paving Strategies and Actions ...............................................................................................................71 1. Increasing Awareness Through Demonstration and Outreach ..............................................................71 2. Policies for Parking, Medians, and Freeways ........................................................................................72 3. Incentives and Regulations ....................................................................................................................73 Endnotes ....................................................................................................................................................................76

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    DALLAS URBAN HEAT ISLAND OVERVIEW DALLAS SUSTAINABLE SKYLINES INITIATIVE: DALLAS URBAN HEAT ISLAND STUDY

    Many people understand from their own experience that cities are often hotter than rural areas. Research suggests a difference of 6 to 8ºF. As cities develop, trees and vegetated areas are reduced, natural surfaces are paved, and buildings constructed. Together these changes produce the “urban heat island effect” illustrated in Figure 1.

    Figure 1. Urban Heat Island Effect

    Dallas has recognized heat island concerns in plans and discussions, and there are several

    references in the 2006 Dallas Comprehensive Plan, forwardDallas! The plan’s Vision mentions the heat island effect as a component of policies to help ensure environmental stewardship.1 Heat island policies are also found in other sections of the plan.

    “Central to this Key Initiative is identifying, inventorying and protecting important natural resources, sensitive ecosystems, open spaces and cherished views. Included are policies to mitigate the urban heat island effect, improve storm water management within the city, reduce smog, expand the absorption capacity of floodplains and allow the restoration and rehabilitation of Trinity River riparian corridors.” (emphasis added)

    The Dallas Urban Heat Island Study examines how and where heat island effects occur in

    Dallas and some of the basic tools for reducing impacts, such as expanded tree planting and conservation, use of cool roofing, and application of cool and porous paving. The study describes costs and benefits associated with these tools.

    FORMATION OF URBAN HEAT ISLANDS Urban heat island effects were recognized in the 19th century by climatologists who measured differ