Posted by Fiona Saiter on May.15, 2010

©iStockphoto.com - LilliDay

Imagine sitting at work in the middle of the day ready to go home and looking out over the city. What do you expect to see? Plain asphalt roof tops? How about a beautiful green garden space? Urban roof top gardens have many benefits and in the future you can probably expect to see more propping up in cities all over the world.

Roof top gardens help reduce rain runoff, beautify the city, and attract birds, butterflies and insects. They also help reduce the heat in the city environment and within the building. The garden roof top lowers the temperature in the summer months and keeps it warmer in the winter. Heat in the city is a problem called “heat island,” according to the EPA. Cities are warmer than rural spaces and this creates pollution and smog.

In fact, the EPA states, “The annual mean air temperature of a city with 1 million people or more can be 1.8–5.4°F (1–3°C) warmer than its surroundings. In the evening, the difference can be as high as 22°F (12°C). Heat islands can affect communities by increasing summertime peak energy demand, air conditioning costs, air pollution and greenhouse gas emissions, heat-related illness and mortality, and water quality”

The City of Chicago Guide to Roof Top Gardens states that roof top gardens also absorb rainfall helps to reduce rainfall runoff which would normally collect pollution and then be emptied into sewers. Although the cost can be high to create a roof top garden, it can make your roof last twice as long according to howstuffworks.com.

There are several types of Green Rooftops to choose from:

Container Roof Top

This is the simplest and least expensive to start up simply use plants in containers on your roof top. This will still help cool your building but not as much as either an extensive or intensive green roof system.

Extensive

This roof system weighs less than the intensive but still requires a water proof layer applied to the entire roof, the difference is shallower and you use plants that are not very labor intensive.

Intensive

With this green roof system you still need the water proof layer and can get more elaborate. The earth can be deeper and you can grow plants that require more pruning and choose from a larger variety of plants.

Some examples of Urban Roof Top Gardens

Chicago City Hall

Chicago Mayor Richard M. Daley has created a green roof top on Chicago’s City Hall as part of a larger vision of greening the city. He created the roof in part to reduce the Heat Island Effect. Creating a green roof top has not only helped with the air quality around the city but the city saves $5,000 a year on utility bills and creates less pollution from rain run off, according to greenroofs.com.

Trent University

Trent University in Canada has a roof top garden that feeds it students. What do they grow? Quinoa, onions, Amaranth, beans, corn, squash, parsley and 30-40 more plants according to greenroofs.com, The food is grown organically on the roof of the Environmental Science Building and then feed to students at The Spoon, a student-run vegetarian and fair trade café. In addition to growing food they also study the effects of ozone on the food and the potential of plants to clean up pollution. All of this was started by Dr. Tom Hutchinson.

Growing Your Own Rooftop Garden

According to a Cityfarmer article, the gardeners recommended mulching roof top gardens often, watering more frequently than a traditional garden, choosing vegetables that love the sun (like tomatoes) since they like the warmer roof top environment much better. Try to create shade, use compost, and if you don’t have the capability to grow an intensive or extensive garden, then try using containers.

By creating more roof top gardens in the future we are creating more beautiful urban areas, helping to regulate the temperature of the building, lower the temperature of the city, help reduce pollution, reduce stress of city workers, and creating a better life for everyone

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Posted under Alternative Energy and Energy Efficiency, Living.