Here at WC3 Design we have worked on many green roof projects. There are many economical, environmental and physical benefits of the green roof trend.
Green Industry Trend
Most buildings are covered with black slates of nothingness. The black asphalt, tar and gravel covered roofs radiate heat and support rushing water during storms. Ever popular in Europe, the new green roof trend is sweeping the United States. Green rooftops have begun to appeal to homeowners, businesses, and even cities, as an environmentally friendly way of dealing with conventional roof issues. These living roofs make a vacant space useful.
Planting a Roof
The conditions on a roof are very different than the conditions of a normal landscape. Roofs are typically harsh environments with extreme wind, heat, exposure, and limited soil depths. Taking all factors into consideration is the only way to create an effective and safe growing environment. Having too deep of soil or too many plants can cause a roof to collapse, so make all the right observations first.
Also, the type of plant grown needs to be appropriate for the setting and environment. Determining what the owner desires will help you design a better landscape. Determine goals such as rain water harvesting, gardens or ornamental plantscapes.
Regardless of the goal of the roof, a waterproofing membrane is built into the surface of a building’s roof. Then, a growing medium is layered over the membrane to act as a “living wall” that the vegetation can grow into.
There are many benefits to green roofs. Benefits are public, private and design based.
Green roofs last longer than conventional roofs and create natural installation, which reduces energy costs. The greater insulation offered by green roofs can reduce the amount of energy needed to moderate the temperature of a building, as roofs are the sight of the greatest heat loss in the winter and the hottest temperatures in the summer.This could reduce demand on power plants, in turn reducing the amount of CO2 and other pollutants being released into the air.
For the Public
In replacement of the unused harsh looking roofs, green roofs create peaceful retreats for people and animals. Adding green roofs is an easy and effective strategy for building the look and appeal of a city. Green roofs can serve as community gardens, commercial spaces or recreational spaces. Green roofs can sustain a variety of plants and invertebrates, and provide a habitat for various bird species. The installation of the plants serve as a great noise barrier, developing a peaceful space.
Because of the greenery, living roofs contribute to storm water management. On average, green roofs retain 70-90% of precipitation during the summer and 25-40% during the winter. This helps prevent runoffs and flooding. In turn, potentially lessening the need for complex and expensive drainage systems. Green roofs reduce the amount of stormwater runoff and also delay the time at which runoff occurs, resulting in decreased stress on sewer systems at peak flow periods. Green roofs not only retain rainwater, but also moderate the temperature of the water and act as natural filters for any of the water that happens to run off.
Green roofs improve air quality. They are being implemented to help fight the Urban Heat Island Effect, a condition in which city and suburban developments absorb and trap heat. Through the daily dew and evaporation cycle, plants on vertical and horizontal surfaces are able to cool cities during hot summer months. The light absorbed by vegetation would otherwise be converted into heat energy.
Green roofs can also help reduce the distribution of dust, particulates, gases and smog in a city. This occurs when plants on green roofs capture airborne pollutants.This can play a role in reducing greenhouse gases.
Green roofs can also contribute to landfill diversion in several ways. First, by using recycled materials in the growing process. Prolonging the service life of heating and ventilation systems contributes as well. Green roofs also, prolong the life of waterproofing membranes, reducing additional waste.
Green roofs can increase a building’s marketability. They are an easily identifiable symbol of the green building movement and can act as an incentive to those interested in the multiple benefits offered by green roofs. Green roofs have increased property value due to increased efficiency. Buildings with green roofs have also found it is easier to recruit employees. Lower employee and tenant turnover are also a response to green roof buildings.
Due to the endless benefits of green roofs, many homeowners, businesses and cities are implementing the trend. As designers, we appreciate the art, craft and environmental influences green roofs have. One of the several green roof projects we have worked on is the Mima Roof Terrace.
Mima Roof Terrace is a rooftop environment to serve as “the Village Green.” It was designed by HM White Site Architects and won awards with the New York ASLA Chapter and achieved LEED Gold Certification. The site was intensely planted with several differing atmospheres. Even with low water pressure we were able to design an irrigation system that met the site plant needs and yet is very efficient and unobtrusive.