A green roof is a roof of a building that is partially or completely covered with vegetation and soil, or a growing medium, planted over a waterproofing membrane. Green roofs reduce city “heat island” effect, reduce summer air conditioning cost and reduce volume and peak rates of stormwater.
Green roofs can also be roofs that utilize some form of "green" technology, such as solar panels or a photovoltaic modules.
Green roofs are referred to as eco-roofs, vegetated roofs, living roofs, and greenroofs. Green roofs are categorized as intensive, "semi-intensive" or extensive.
There are two main utilization options for green roofs: one, as a roof garden with a pleasant view for the owner; the other, a habitat for flora and fauna within grey city centres. Green roof systems can cost $5-10/sqft.
Intensive green roofs ususally have a soil depth of a foot or more, and require substantial structural elements to support the weight of the whole roof. Intensive roofs can sustain a wide range of plant species and typically require a fair amount of regular maintenance. Intensive green roofs are more expensive to set-up, require high maintenance, regular irrigation, and include various plants from kitchen herbs to shrubs and small trees.
Semi-Intensive green roofs are designer roofs with less maitenance requirements and set-up costs then Intensive green roofs. Semi-Intensive green roofs sustain herbs, shrubs and grasses, and require periodic irrigation.
Extensive green roofs are well suited to roofs with little load bearing capacity, usually 2 to 4 inches deep, and sites which are not meant to be used as roof gardens. Extensive green roofs sustain moss-sedum-herbs and grasses, are low maintenance and require no irrigation. Extensive green roofs are cheap to se-up and are used mainly as a Ecological protection layer.
Green roofs:
- Reduce city “heat island” effect
- Reduce CO2 impact
- Reduce summer air conditioning cost
- Reduce winter heat demand
- Potentially lengthen roof life 2 to 3 times
- Treat nitrogen pollution in rain
- Negate acid rain effect
- Help reduce volume and peak rates of stormwater- a green roof retains 50%-90% of a typical rainfall
There are three typical options for installing a green roof:
- Work with a company who specializes in green roof applications
- Work with an architect who has experience with green roofs for residences
- Do it yourself
Green roofs are ideal for flat-topped roofs in urban settings, where the roof temperature can drop from 160°F to 80°F, reducing the city “heat island” effect. Green roofs can also reduce air and noise pollution. Green roofs are also aesthetically pleasing, especially in urban environments.
For those not willing to invest ia green roof, a white roof is an easy home cooling option. Roof whitening is a mid-cost solution that can cut your home cooling costs by quite a lot. Home owners can expect to save 25-43% on air conditioning costs. Coatings cost 30-70 cents/sqft of roof surface area. Your basic white roofing paint is the ideal coating for the best results.
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