A green roof located on top of the Chicago City Hall
For the most part, cities consist of roads, sidewalks and buildings that are made of cement, asphalt and steel. Cities are not typically known for having types of green spaces. However, over the year’s rooftop gardens and other types of green roofs have been becoming more common in urban areas. Green roofs not only have environmental benefits, but they can also save energy and money, reduce greenhouse gas emissions and provide amenities for people living in urban spaces.
One major benefit of green roofs is their ability to capture and retain rainwater. When precipitation falls on a regular roof, most of the water runs off and into sewers, often taking pollutants with it. A green roof is able to capture roughly 80% of rainwater compared to 24% of a regular roof. This amount is able to increase as long as the plants continue to grow. A more mature rooftop system can even act as a filter and trap particles. Some cities, like San Francisco, are having problems with their storm water management systems. They are now turning to green roofs as a way to deal with the aging infrastructure in a cost effective way. Another problem that San Francisco is trying to decrease is the amount of pollutants that are entering the Bay. Runoff often results in an overflow in sewer systems, which transports pollutants to the Bay.
Green roofs can also provide more energy efficient buildings and save money in the long run. Other types of roofs are dark and absorb a lot of heat from solar radiation. This causes there to be a higher demand to cool a building down. A green roof can reduce the temperature of the roof and provide insulation. By reducing the amount of energy needed to cool a building, there is also a reduction in the greenhouse gases being emitted by cooling systems. In colder regions it’s typically for a greenhouse not to function all year round due to heating costs. Some manufacturers are looking to be able to have year round greenhouses on roofs by using heat from forges that can melt tools and car parts. This has enabled some areas to grow fruits and vegetables year round. This has allowed residents of cities to gain access to fresh produce, which has helped to improve public health.
Cities around the world are constantly expanding, which is why it’s important for green roofs to be constructed in these areas. Green roofs are beneficial in cities because they are aesthetically pleasing and can connect people to nature. With climate change comes unpredictable weather patters. Green rooftops can help with excessive rainfall and fluctuations in temperatures. Equations are being used in some cities to determine how effective a green roof would be. Lighter colored roofs have been suggested to help reduce the temperatures in cities. However, there is the possibility that these types of roofs may just redistribute the heat. The lighter roofs also don’t help with reducing rainwater run off. Cities are becoming more invested in green roofs because of the many benefits. France recently passed a law that all commercial buildings must have roofs that are partially covered with plants or solar panels. This is a good example of a city taking steps in the right direction. Legislation can be used to make beneficial changes in cities in terms of reducing runoff, pollution, reductions in greenhouse gas emissions, saving on energy and costs and providing amenities to the citizens.