Saturday, February 2, 2008

The Other Global Warming: Urban Heating

A problem that I think a lot of people (outside of this class, of course) are not aware of is urban heating. Any solution to climate change is going to have to involve reducing urban heating. According to the EPA (here), urban heating raises temperatures 2 - 10 degrees Fahrenheit during summer months. This increases ground level ozone, electricity use to power air conditioners, air conditioner waste heat which further increases urban heating and helps to kill poor old people on hot days. Reducing urban heating is fairly simple, for example painting roofs with high solar reflectance materials (white roofs) to reflect more of the sun's energy and planting trees for shade and evapotransporation cooling. Certain types of pavement also can reduce heat absorption. Planting trees makes any urban area more agreeable and painting roofs is a very inexpensive and simple process. This is simple stuff that any city can implement at minimal cost and effort. Cool roofing coating often reduce roof surface temperatures up to 70 degrees. Every warehouse in Texas could probably save money with a cool roof. Hopefully cities and utilities will use these simple tools to help combat climate change.


Colin Smith said...

Generally I think this is a good point, but what about Boston in January? The other side of urban heating is keeping heating costs down in the winter.

Jrod said...

I think another solution to the problem of urban heating is green roofs. I saw that you mentioned planting trees for shade and evapotransportation cooling, but you didn't directly mention green roofs. Although the cost of a green roof is quite a bit higher than the cost of a traditional roof ($8 per square foot vs. $1.25 per square foot based on info from EPA's website), but in the long run the advantages from not only reducing urban heating, but also from mitigating storm water run off, absorbing air pollution, protecting the underlying roof and therefore increasing the life of the building, and providing insulation for the building from cold winters or hot summers I think are enough to outweight the additional costs. I know that the green roof idea has grown over the last few years and even large companies like Ford are implementing them (see the article here). Hopefully more and more individuals and companies will embrace the greenroof.