19 Jun Albedo Austin

As I was walking home along one of our boiling black asphalt streets this afternoon, I got to thinking about albedo. If all of our streets were white, they would reflect the sun’s heat back into the atmosphere, rather than trapping it down here with us on an already hot summer day.

This would certainly help combat the urban heat island effect we experience, whereby central Austin is always a few degrees warmer than the surrounding countryside, because of its color and material composition. This effect does help us grow citrus and other tender plants that we wouldn’t normally grow in Central Texas, but it really takes a toll in summer. More heat means more evaporation and more transpiration of water in an area already already stricken by extreme-drought.

Unfortunately, lightening all of our streets could become a monumental project, with its own malicious environmental impacts, unless we can find a solution in another waste stream.

A Local Problem/Solution
With all of the development currently taking place in Austin, we throw tons of excavated limestone into huge pits along the Colorado River plain east of town, where we’ve already mined out the reddish clay/loam for so called “top soil” or “fill dirt”. Instead of wasting this stone and the river’s landscape, couldn’t we just mix it into our existing road aggregate on all future road repair and construction projects? This would slowly begin lighten the color of all our city streets, cooling the city, recycling wastes, reducing water loss, and even increasing the effectiveness of and reducing the need for street lighting.

Adjusting Austin’s albedo this way, along with extensive street tree planting, might make our summers a little more bearable for everyone dealing with the Texas heat.

Now, if we could only make all our streets pervious to infiltrate and filter rainwater–feeding the river and fighting the drought in another way.

For more info on albedo and other useful things you can do with a street, see:
Cool Paving @ Earth Encyclopedia
Cool Communities