In addition to stocking up on farm fresh provisions at the DUH market, I recently had the pleasure of chatting a bit with local vegetated roof system designer, Kody Cronan. Among other projects under the banner K/Lab/Rative studio, Kody installs green/vegetated/living/eco roofs. Even within our brief conversation, I learned quite a bit about the logistics and viability of urban green roofing that inspired me to look further.

Here in Denver, you can find eco-roofs on the building occupied by the Environmental Protection Agency, the Museum of Contemporary Art and the Denver Botanic Gardens gift shop. Though actual green roofs are a little slow to catch on here, I am noticing more thriving rooftop gardens than ever, most commonly atop the old downtown buildings converted to lofts. Not only is it beautiful and heart-warming to witness the greening of our urban landscape, it’s also smart, practical and responsible. I encourage anyone interested to embark on more extensive research, but consider the following information (excerpted from an article by Kent Swanson) a primer on the subject.

Using the roof of a building as a green space has innumerable benefits, especially in urban areas where green spaces can be few and far between. First and mostly obviously, green roofs can dramatically improve the aesthetics of the urban landscape. Secondly, there are many environmental benefits to installing a green roof, including reduced ambient temperatures (and thus reduced air-conditioning use), improved air and water quality, less rainwater runoff, reduced noise pollution, and the creation of wildlife habitat.

Green roofs also have economic benefits, as they typically last longer than traditional roofs. Most commercially built green roofs in Germany these days include a warranty of up to 30 years. Green roofs can also help lessen the demand on municipal drainage systems, reducing the costs of maintenance and repairs. Furthermore, green roofs can serve as educational and recreational spaces.

A recent article in the New York Times stated that in cities where high temperatures get to 95 degrees Fahrenheit, some roofing materials can reach up to 175 degrees. Meanwhile, a layer of turf often stays below 77 degrees. The creation of green roofs can thus help to reduce the problem of the urban “heat island.” Plants naturally cool things off through a process called evapotranspiration, creating a cool and comfortable microclimate. The addition of trees to a green roof creates shade, complimenting the evaporative cooling effect. The reduced temperature on the roof translates to reduced temperatures inside the building, and less time with the air-conditioning turned on. By greening the roof of City Hall, city officials in Chicago aspire to reduce air-conditioning costs by about $4,000 a year.

In large cities, some reports suggest that an average of 75% of rainwater becomes runoff. As this water washes off of roofs and streets, it picks up contaminants which eventually make it to rivers and lakes. The large quantities of water also stress the storm water infrastructure of cities. With the addition of a green roof, more of this water is put to beneficial use. A report by Temple University claims that 75% of the water applied to an extensive green roof is used by the plants and soil. The remaining 25% is released gradually as runoff. This gradual flow is much easier to control and contain than the rapid runoff produced by large rainstorms. With the addition of rain barrels or rainwater storage systems, runoff can be all but eliminated.

Of course, more plants mean cleaner air, due to the fact that plants convert carbon dioxide into oxygen. Plants can also trap dust particles. They also help to reduce another form of pollution as they absorb the noise from a busy urban landscape. Additional green spaces create habitat for birds, butterflies, and other wildlife, helping to mitigate the environmental impact of growing urban areas.

If you live in the big city, you can probably imagine even more benefits to installing green roofs. More gardens mean happier and friendlier people, as urban dwellers will have more opportunities to gaze at beautiful flowers and trees. Maybe you can take your children to visit these unusual urban gardens to learn more about plants and gardening. Perhaps people will have reduced stress levels due to the presence of more green spaces. Some professionals working on green roof technology even claim that if enough cities install a substantial number of green roofs, over time it can help us significantly reduce our reliance on fossil fuels through energy conservation.

The rise in the number of green roofing projects throughout the world is a promising sign that we have learned the importance of replacing the green spaces lost to our rapidly urbanizing society. More and more governments are requiring green spaces in new construction projects, and even much maligned corporations such as Target are contributing to improving urban landscapes by installing green roofs. With modern technology and inventiveness, green roofs can become a real solution to many of the environmental problems that we are facing today.

It is my hope as well that more individuals will start to explore the possibilities of adding green roofing technologies to their own homes. This way, we can all play a role in helping the environment and improving the urban landscape.

Green Roof Information and Resources

_______________________________________________________

In my conversation with Kody, we acknowledged the understandable trepidation among homeowners in pioneering the movement here in Denver. Would they look strange, would there be logistical or long-term problems, would it end up costing more…? True, there are many considerations to be made and thus the need for experienced installers like Kody. The more cautious of pioneers may opt to try it first on patio shelters, carriage houses, alley garages, workspaces and sheds.

Or how about testing the waters with the kids’ fort, dog’s house or bird house?