Not just a roof: Greening buildings, literally
When walking through Millenium Park in Chicago, it looks and feels just like any other park: paths intertwine through beautifully manicured gardens, kids play in water structures and tourists take artsy pictures of their reflections in the Bean. What some may not realize is that below the surface lies a train yard and two parking garages. Millenium Park is a testament to the innovative ways cities are beginning to rethink arguably one of the ugliest aspects of cities: roofs. At 99,127 square meters, Millenium Park is the largest green roof in the world, followed by the Frankfurt International Airport in Germany at 80,000 square meters. You can learn more about the world’s top 10 largest green roofs here, but for a quick overview of where the largest green roofs, or "eco roofs" are located, check out the image below.
According to Robert Payne, spokesman of Fraport AG, the company that built Frank International’s green roof, the roof has made a noticeable difference in building temperature, cooling down the entire terminal building. This cooling effect is only one of the many benefits of green roofs. Other benefits include:
- Reduce cooling loads
- Create habitats for wildlife
- Increase property value
- Filter pollutants and carbon dioxide out of the air and out of rainwater
- Help insulate against sound
- Can provide agricultural space
- Decrease storm water runoff
Storm water regulations: a driving force in green roof adoption
The last benefit has been the main motivator for cities to encourage building owners to embrace green roofs. Wastewater system overload and flooding are common problems in cities during heavy storms, causing raw sewage to dump into local waterways. Green roofs are an effective method of storm water management, retaining up to 75% of rainwater. Several cities have enacted storm water management regulations, driving the adoption of green roofs. Pittsburg, for instance, requires properties greater than 10,000 sq ft have on-site retention of the first inch of rainfall through some combination of infiltration, evapotranspiration, and rainwater harvesting. Portland, Oregon, requires new city-owned buildings and existing buildings replacing roofs to install a green roof that covers at least 70% of the roof area. You can learn about other legislation regarding green roofs and other building regulations here.
More fun facts about green roofs
- Green roofs can be traced back several centuries to the Hanging Gardens of Babylon, with modern day green roofs being developed in Germany in the 60s.
- Green Roofs for Healthy Cities found that in the U.S. and Canada, the green roof industry has increased by 115% between 2010 and 2011.
- A green roof at the Croton Water Filtration Plant in New York, set to be completed in 2014, will include a 36,512 square meters golf driving range!