The green roof: a worthwhile investment

Green roofs save money in the long run and are far more environmentally friendly.

Green roofs remain much cooler than traditional roofs
Green roofs remain much cooler than traditional roofs

Nestled in the heart of Chicago, atop city hall, lies a sliver of green amidst the sea of concrete and steel. Completed in 2001, this green roof was spearheaded as an experiment by the then Mayor Richard M. Daley. The idea behind the project was to test out different types of green roofs to see if they are viable ways to combat environmental degradation. Fifteen years later, we can see evidence that Mr. Daley was onto something. Before we get into that though, what is a green roof exactly?

When one refers to a green roof they are talking about a rooftop that has been vegetated, regardless of how extensive it is. There are two types of green roofs, extensive and intensive. An “extensive” green roof is focused on simple lightweight designs with hardy plants. There are two benefits to this type: 1) they require far less maintenance and do not need a permanent irrigation system, which saves costs; and 2) since these plants are lighter than other flora, it does not require as much structural support of the rooftop, which also saves money.

The second type are known as “intensive.” These consist of more complex plants that are arranged in a more ornamental way. While this design provides the same environmental benefits, it is costlier and more difficult to develop. The major advantage it has over the extensive style is that it doubles as a green space for people to go and visit. This is extremely useful in dense urban centers where parks can be few and far between.

According to a University of Michigan study from 2006, the benefits of green roofs run beyond environmental improvement. In the long run, they can actually save money compared to a traditional roof. According to the study, a green roof will cost around $464,000 ($556,561 in 2016 dollars), and $335,000 for a conventional roof ($401,827 in 2016 dollars). However, over the life of the green roof it is estimated that it will save around $200,000 ($239,897 in 2016 dollars) in energy costs. That is because green roofs absorb much of the heat from the sun, causing the rooftop to be about 80 degrees cooler than a traditional rooftop. The green roof also can insulate the building itself so that less heat goes to waste in the winter. According to the EPA the Chicago City Hall Green Roof saves approximately $3,600 in heating and cooling costs annually.

The environmental advantages don’t stop there though; the EPA also states that green roofs help sequester the concentrated levels of carbon being released in city centers. In turn, green roofs help combat climate change, keeping things even cooler. The fact that green roofs can do so much for the environment is substantial on its own, but the fact that in the long run it actually saves money makes implementing them in your own community worthwhile.

Looking for more information about green roofs? Check out the Michigan State University Green Roof Research project. In addition, Michigan State University Extension has educators around the state who can provide information on green roofs and other sustainable development practices.

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