Keeping Your Cool on a Heat Island

Jessica on Heat Island

Jessica on Heat Island

It’s 9 a.m. and I’m on my way to my internship at EPA. I’m sweating through my clothes, my hair is plastered to my neck, and mascara is pooling under my eyes. The summertime heat and D.C.’s swampy humidity are bad enough, but an extra dose of suffering comes from the heat island effect.

Washington, D.C., like many developed areas, is a heat island: all of the pavement and buildings absorb and retain much more heat than less built up areas. This means they can be 1.8 to 5.4°F warmer on average, and up to 22°F warmer in the evening.

 

 

Temperatures climb more among buildings and roads than open land and vegetation.

Temperatures climb more among buildings and roads than open land and vegetation.

Heat islands aren’t only uncomfortable, they can be hazardous to people’s health. And, they can create a vicious cycle: higher city temperatures mean more electricity is needed to cool buildings, which in turn may increase air pollution. Also, when an extreme heat wave hits a city already stressed by the heat island effect, it can increase the risk of heat-related illness and death. This risk is worse for children, the elderly, and the ill, who are more vulnerable to extreme heat and polluted air.

EPA’s Heat Island Reduction Program suggests several strategies that cities can take to reduce summertime heat islands:

  • Planting trees near buildings: Trees and other plants help cool the environment.
  • Installing green roofs: Green roofs provide shade and remove heat from the air.
  • Installing cool roofs: Cool roofs have a high solar reflectance that helps reflect sunlight and heat away from the building.
  • Using cool pavements: Cool pavements reflect more solar energy, enhance water evaporation, or have been otherwise modified to remain cooler than conventional pavements (like those that allow water to permeate below the surface).

These tactics reduce demand for energy to cool buildings, which cuts carbon pollution and lowers bills. Using these cool technologies reduces the heat island effect, helping everyone stay cool.

Permeable pavement reduces runoff, mitigating heat buildup and improving drainage.

Permeable pavement reduces runoff, mitigating heat buildup and improving drainage.

 

The city heat can be a real nuisance (especially when trying to look professional for work!), but it can also be dangerous. Luckily, there are plenty of things that can be done to combat the heat island effect and keep safe in the heat. Listening in on heat island webinars and calls, I’m excited to hear about how communities are taking action to make life safer and more comfortable for residents. There’s a lot we can do as individuals and communities to reduce heat island, and those efforts can add up and have a big impact for us and the environment.

And there’s some good news for D.C. The District Department for the Environment recently created a Green Building Fund Grant Program, which has several goals, including assessing the health impacts of urban heat islands in this city. So, hopefully, future interns will benefit from this research and resulting policy changes. What is your city doing to reduce the heat island effect?

About the author: Jessica D’Itri is a Master of Public Policy student at the Gerald R. Ford School of Public Policy at the University of Michigan. Prior to attending the Ford School, she served as an environmental educator with Peace Corps Nicaragua. She is interested in learning how communities and local governments can implement policy to best benefit people and the environment.

Editor's Note: The views expressed here are intended to explain EPA policy. They do not change anyone's rights or obligations. You may share this post. However, please do not change the title or the content, or remove EPA’s identity as the author. If you do make substantive changes, please do not attribute the edited title or content to EPA or the author.

EPA's official web site is www.epa.gov. Some links on this page may redirect users from the EPA website to specific content on a non-EPA, third-party site. In doing so, EPA is directing you only to the specific content referenced at the time of publication, not to any other content that may appear on the same webpage or elsewhere on the third-party site, or be added at a later date.

EPA is providing this link for informational purposes only. EPA cannot attest to the accuracy of non-EPA information provided by any third-party sites or any other linked site. EPA does not endorse any non-government websites, companies, internet applications or any policies or information expressed therein.

Surviving on this Island

I’ve often walked around Chicago in the peak of summer, only to feel the pavement underneath my feet feel as if it sizzling in the beating sun.   It’s hot.  I literally feel like a piece of frying bacon on the sidewalk sometimes.   It’s a heat island. 

A heat island is a built-up area which is consistently hotter than its surroundings, particularly in the summer.  The heat island effect is caused mostly by the difference between the generally dark surfaces of a city like roads and sidewalks and the vegetation it’s replaced. These dark surfaces absorb sunlight, heat up, and retain more heat than open space areas.  Add hot air from vehicle exhausts and industry, the temperature rises even more.

There is one place that I know of that is high above the pavement of the city streets and it’s still cool.  It’s the green roof on top of City Hall.  In 2001, it was completed and took this large underutilized space in the thick urban Chicago jungle and created an oasis of green living.  The 20,300 square foot City Hall rooftop garden has over 20,000 native plants that were installed as plugs of more than 150 varieties.  Although rainwater is collected and saved, a supplemental irrigation system aids in establishing the plants as well as provide supplemental water during extreme periods of drought.  Pretty neat, huh? 

I wondered about the inside of the building and so I asked a few members of the staff about their thoughts on the green roof.  Did it make a difference?  All agreed that it insulates the building, making it warmer in the winter and cooler in the summer.  They also noticed that when they walk out of the building, immediately there is a cool breeze surrounding the building before they step further out into the thick humidity of the day. 

If a green roof is helping change the heat island effects in one part of Chicago, think about what it could do if they were all over the country.  Communities can take a number of common-sense measures to reduce the effects of summertime heat islands.   You can help! 

To find out more, go to http://www.epa.gov/heatislands/index.htm

Yvonne Gonzalez is a SCEP intern with the Air and Radiation Division in Region 5. She is currently pursuing a dual graduate degree at DePaul University.

Editor's Note: The views expressed here are intended to explain EPA policy. They do not change anyone's rights or obligations. You may share this post. However, please do not change the title or the content, or remove EPA’s identity as the author. If you do make substantive changes, please do not attribute the edited title or content to EPA or the author.

EPA's official web site is www.epa.gov. Some links on this page may redirect users from the EPA website to specific content on a non-EPA, third-party site. In doing so, EPA is directing you only to the specific content referenced at the time of publication, not to any other content that may appear on the same webpage or elsewhere on the third-party site, or be added at a later date.

EPA is providing this link for informational purposes only. EPA cannot attest to the accuracy of non-EPA information provided by any third-party sites or any other linked site. EPA does not endorse any non-government websites, companies, internet applications or any policies or information expressed therein.