What is a Green Roof?
Green roofs are vegetated roof covers that take the place of bare membrane, gravel, shingles or tiles. There are many variances of green roof types, but all green roofs include a waterproofing system, a drainage layer and soil and or/plants. Concrete roof pavers and wooden roof decks are also often a part of green roofing systems.
There are two kinds of green roofs:
- Extensive: These roofs are low-profile and include fewer layers than an intensive system. They are less expensive and require very little maintenance. Extensive green roofs can be constructed on slopes up to 30 degrees and steeper ones can be installed with raised grids or laths to hold plants and soil media in place. Green roofs require watering occasionally during the first year of establishment. If you have chosen the correct drought tolerant plants wisely for your area, except in extreme periods of drought, they do not require watering.
- Intensive: These roofs look like traditional gardens because a much wider variety of plant material can be included since growing media depths are increased. Green roofs need to be treated like gardens. High winds are especially drying, so Intensive Green roofs require a bit more water than ground level gardens. Usually large intensive Green roofs have an irrigation system installed.
Why go Green?
Lower Your Bills, Get a Tax Break and Increase the Value of Your Property
You cannot go wrong. Environment Canada found that a one-story building with a grass roof and 3.9 inches of growing medium could result in a 25% reduction in summer cooling needs.
Make Your Business Visibly Eco-Friendly
Public anger towards traditional “unecological” industries can be mitigated by a company’s environmental awareness as illustrated by their Green roof.
Extend the Life of Your Roof
While most roofs require replacement every 15 to 20 years, green roofs have a life expectancy of 30 to 35 years.
Increase Usable Space
Your roof does not need to be a useless surface. Green roofs grant the potential for roof space to be an enjoyable atmosphere for anyone. Additionally, your building’s worth is heightened when it has a Green Roof.
Your roof no longer needs to look like a roof. Green roofs provide a natural looking environment that is both aesthetically and tangibly pleasing. Green roofs can also be designed in countless ways.
The exact amount of noise reduction is hard to quantify and depends mostly on the thickness of the soil substrate and additional factors, but overall, up to a 50 decibel noise reduction can be realized (McMarlin, May/June, 1996).
Green roofs, because of their very nature (green), convert carbon dioxide into oxygen.
Reduce of the Urban Heat Island Effect
Heat Island effect refers to the difference in temperature between a city and its surrounding areas. The difference can be as significant as 10 degrees. Green roofs combat the urban island effect due to the increased vegetation they bring to the urban landscape. Plants cool their surrounding environments through natural evaporation cycles. With more green roofs in the city and less, non porous blacktop, cities will cool down.
Storm Water Retention
Green roofs retain up to 75% of a one-inch rainfall and therefore alleviate the pressure of the city’s sewer systems. Because green roofs retain more water, the amount of water that picks up dangerous particulates on its way to the sewers in lessened. Additionally, during storms, cities often combine their storm water with their household sewage waste due to the increased pressure on treatment plants. Thus, raw, untreated sewage is often released untreated into city waterways.
Green roofs have the potential to reduce the ambient air temperature in a city. In addition to their contribution to lower temperatures during the summer months, and the subsequent lower demand for electricity, green roofs are provide important insulation during the winter months, once again resulting in a lesser demand for heat energy.
Take Advantage of the Many Economic Benefits of Green Roofs
Green roofs have the potential to:
- Reduce the size of HVAC equipment on new or retrofitted buildings (capital and operational savings).
- Reduce the amount of standard insulation used.
- Incorporate cooling and/or water treatment functions.
- Reduce or eliminate roof drains.
- Meet regulatory requirements for stormwater management.
- Reduce community resistance to new developments.