In downtown Phoenix, cooler pavement for parking lots

To battle the urban heat island effect, city officials in Phoenix have approved the installation of a downtown city parking lot made from "cool pavement."
Written by Andrew Nusca, Contributor

To battle the urban heat island effect, city officials in Phoenix have approved the installation of a 90,000-square-foot temporary parking lot made from "cool pavement" in the city's downtown area.

The asphalt in the parking lot, which is located between First, Second, Taylor and Polk streets, is treated with a permanent solar reflective coating made by Emerald Cities.

The "Celadon Green" coating promises to reduce the surface temperature of asphalt by at least 30 degrees Fahrenheit on hot days -- a phenomenon a desert city like Phoenix sees most of the year.

Installation began last Wednesday, with spray crews working by moonlight to treat the lot. It will be unveiled to the public on June 10.

If you've ever been to a major city during the summer, you'll know that it's no fun to walk the streets. With blackened asphalt used in streets, pavements and sidewalks absorbing copious amounts of sunlight as heat, a city's grid quickly heats up.

In a southwestern city like Phoenix, well, that's some serious heat: air temperatures to the tune of 115 to 118 degrees Fahrenheit, with blacktop temps pushing 170 degrees.

Aside from discomfort, the heat poses significant problems for sustainability and efficiency for a city. With air conditioners blazing, a city utility could quickly see demand top capacity, causing a brownout or blackout. The heat damages the asphalt itself, which is money lost for the city. The heat aggravates air pollution, causing additional health issues for susceptible residents such as children or the elderly. And it's certainly doing no good for the sustainability goals of the city or private corporations headquartered there.

While urban planners have been working to reinstall green zones in the concrete jungle -- grassy fields and trees do a great job at absorbing carbon dioxide, shading pedestrians and keeping pavements cool -- it's not enough.

We've seen porous pavements for water runoff control; now meet a street-savvy answer for heat. Manufacturer Emerald Cities says its coating -- which uses Colloidal Nano Silica, superplasticizers and polymers and solar reflective pigments -- solves the problem by lightening the color of asphalt.

It's a bit like those new, light gray roof tiles you've seen at your local home improvement store. By reflecting the heat instead of absorbing it, your home's temperature is more easily regulated, in both winter and summer.

In 2008, Energy secretary Stephen Chu said the following:

Changing surface colors in 100 of the world's largest cities could save the equivalent of 44 billion tonnes of carbon dioxide — about as much as global carbon emissions are expected to rise by over the next decade.

Perhaps this treatment is the answer.

This post was originally published on Smartplanet.com

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