CAE: 4 Ways Your City Can Be Cooler Next Summer

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4 Ways Your City Can Be Cooler Next Summer


By Virginia Hewitt, Local Policy Research Assistant


This summer was a scorcher. Heat waves repeatedly struck the Midwest and South, sparing only sections of the Northeast. All of California is still in a drought. Cities were especially hot due to their concentration of buildings and human activity, a phenomenon called the urban heat island effect. At times, it may have felt impossible to beat the heat. Luckily, a recent report from ACEEE and the Global Cool Cities Alliance, Cool Policies for Cool Cities, shows how local governments enable communities to beat the heat before it starts. By employing the following cooling and energy-efficient practices before next summer, cities across North America can keep their cool:


Plant a Tree. A Chinese proverb says, “The best time to plant a tree was 20 years ago. The second best time is now.” Older trees with broad leaves and reaching branches provide a lot of shade for parks, pavements, homes, and offices, helping to keep them cool. They also clean the air and produce oxygen. Local governments often plant trees on city land, but did you know that many cities also provide free or discounted trees for planting on private land?

Paint your roof. Dark-colored roofs trap and store heat. This heat radiates into the building, and doesn’t dissipate at night. Trapped heat is unpleasant and costly for residents who are forced to crank their AC, and is dangerous, sometimes deadly, for residents who don’t have access to air conditioning. A light-colored or reflective roof traps and stores considerably less heat. Cool roofs, for the same price as dark roofs, reflect the sun’s rays back out into the atmosphere. Recognizing the energy-efficient and publicly beneficial nature of cool roofs, some cities (and the entire State of California) require or encourage new and updated roofs to be reflective.

Replace dark pavement. Dark pavements also absorb, trap, and slowly release heat. You’ve experienced this running barefoot across a blacktop basketball court or parking lot. Light pavement, on the other hand, can be 50°-70°F cooler. Replacing dark pavement with vegetation also reduces the urban heat island effect. Grass and other permeable surfaces keep a city’s temperature down compared to pavement. As a bonus, they also filter stormwater. Cities have begun to encourage residents to paint parking lots, play areas, and alleyways with reflective coatings, or replace them with porous materials.

Vegetate your roof. A green roof eliminates the negative heat effects of a dark roof, and adds the benefits of oxygen exchange, amenity space, and opportunity for urban agriculture. Building a vegetated roof may seem like an expensive project, but many local governments are willing to share your costs…


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About ACEEE: The American Council for an Energy-Efficient Economy acts as a catalyst to advance energy efficiency policies, programs, technologies, investments, and behaviors. For information about ACEEE and its programs, publications, and conferences, visit