Energy Efficient Roof: Green Roofs
A green roof, also called a living roof, is an energy-efficient roof that is partly or totally covered with plants and a growing medium, which is layered on top of a waterproof base. It might also contain a root barrier with drainage or irrigation systems. Some Houston roofs have container gardens with potted plants, but purists do not classify these as true green roofs. Graywater, also known as wastewater, can be treated in rooftop ponds on green roofs.
Green roofs are almost always on commercial buildings like arenas, high rise buildings or other large structures. Green roofs absorb rainwater, insulate the building and provide areas for wildlife. They also present a more pleasant landscape that helps to lower urban air temperatures and reduce the heat island effect.
Water is stored by the substrate on green roofs. The plants then use the water and release it into the atmosphere via transpiration and evaporation. Green roofs also affect the temperature of rainwater and filter any storm water that might run off the building.
Types of Green Roofs
A knowledgeable Houston commercial roofing company offers two types of green roofs.
- Extensive roofs are shallow. They are usually not more than 2 cm to 12.7 cm deep. They need minimal maintenance.
- Intensive roofs are at least 12.8 cm deep so that they can support more types of plants. They require extra maintenance.
Green roofs are known by many names, including: eco-roofs, living roofs, oikosteges, vegetated roofs, and HVCP (Horizontal Vegetated Complex Partitions) roofs. A green roof can also be a roof that uses some type of green technology like a cool roof or a roof with photovoltaic panels or solar collectors.
Benefits of a Green Roof
- Reducing heat with the addition of mass and a thermal resistance value
- Reducing the need for air conditioning by 50 to 90 percent
- Reducing storm water runoff by more than 75 percent
- Creating natural habitats
- Filtering carbon dioxide and pollutants from the air
- Filtering heavy metals and other pollutants from rainwater
- Increased agricultural area
- Insulating the building from noise
If the green roof is covered in glass, it acts as a terrarium and a passive solar heat reservoir. In urban areas that have numerous green roofs in close proximity to each other, they can even lower the city’s average summer temperatures.
Green roofs also have financial benefits. They can extend a roof’s lifespan by more than 200 percent by protecting the roof from UV rays and damage. They also increase a building’s value by about 7 percent.
Some areas offer financial incentives for green roofs, such as grants, rebates or tax reductions. These incentives are most common in areas with urban heat islands, contaminated storm water runoff or a dilapidated storm water management system.
Paramount Roofing can help you decide if a green roof is right for your building. Call us at 713-748-4000 to discuss how a green roof can save you money, provide a rooftop area for outdoor activities and help the Houston environment.