In his blog, Stanton writes about Temperature Control and he is shocked by the amount of energy we use to cool things. This reminded me of a research project I worked on during high school, "A Comparison of Rooftop Surfaces Using Albedo."
Essentially, in this project, I turned my childhood playhouse, into a research experiment. You can see the picture below. I put a green roof on one third of the roof, left one third as the existing tar roof, and painted the other third with standard white, outdoor paint.
Now you may be asking what on earth possessed me to do this? So let's go through some background information:
One problem very evident in large cities today is something called the Urban Heat Island Effect. This occurs when the cities are significantly cooler than their surrounding countrysides at night. As much as 10-12 degrees Celsius! Why? Well, the abundance of black surfaces in the city absorb great amounts of heat during the day and release it all at night.
One problem very evident in large cities today is something called the Urban Heat Island Effect. This occurs when the cities are significantly cooler than their surrounding countrysides at night. As much as 10-12 degrees Celsius! Why? Well, the abundance of black surfaces in the city absorb great amounts of heat during the day and release it all at night.
So, two of the most promising mitigation techniques are green roofs and white roofs. The idea is to replace the low albedo (low reflectivity) surfaces with other surfaces that have high albedos and will reflect rather than absorb the majority of light. In my experiment, I kept a constant measurement of the surface temperatures for 250 hours. I had a temperature probe on each roof surface on both the East facing and West facing sides.
As for results, well, it turns out these are both very promising techniques! The cold hard facts based on my temperature analysis say that the white roof maintains cooler temperatures and is the 'better' choice. However, we cannot ever simply rely on the facts. As modern-day scientists and engineers we have to critically analyze this data and decide what it actually means. The white roof did indeed keep lower temperatures and had the smallest range of temperature values, which is ideal. But over time, white roofs become dirty and this greatly decreases their albedo. A green roof, depending on which type you choose to install, is little to no maintenance, ascetically pleasing, helps with water runoff, and greatly extends the life of your roof.
As for results, well, it turns out these are both very promising techniques! The cold hard facts based on my temperature analysis say that the white roof maintains cooler temperatures and is the 'better' choice. However, we cannot ever simply rely on the facts. As modern-day scientists and engineers we have to critically analyze this data and decide what it actually means. The white roof did indeed keep lower temperatures and had the smallest range of temperature values, which is ideal. But over time, white roofs become dirty and this greatly decreases their albedo. A green roof, depending on which type you choose to install, is little to no maintenance, ascetically pleasing, helps with water runoff, and greatly extends the life of your roof.
The greenroof I used is a wonderful creation, you can see the layers in the image to the right. this green roof is incredibly easy to install and very low maintenance. It was donated by Xeroflora and still remains looking great on my playhouse roof several months later!
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