Skies of Blue and Green Roofs

One of the coolest things I want to have is a Green Roof. A Green Roof is a roof that is partially or completely covered with vegetation and soil, or a growing medium, planted over a waterproofing membrane. Unfortunately I live in a downstairs unit and a condo (which would never allow this). But if I ever move again (which I will) I will definitely look into putting in a Green Roof.

A couple of great Reference books-

Before you start thinking about doing this, you must look at your structural considerations, zoning and maintenance.

Benefits of a Green Roof: From Green Roofs.org ( Tons of Info on this site- check it out)

Economic Benefits – cost savings opportunities for the building owner include:

Protection of roof membrane resulting in a longer material lifespan (it is estimated that green roofs will last up to twice as long as conventional roofs), resulting in decreased maintenance and savings in replacement costs;
Savings on energy heating and cooling costs, depending on the size of the building, climate and type of green roof. Using a Micro Axess Simulation model, Environment Canada found that a typical one storey building with a grass roof and 10 cm (3.9 inches) of growing medium would result in a 25% reduction in summer cooling needs. Field experiments by Karen Liu in Ottawa Canada, found that a 6 inch extensive green roof reduced heat gains by 95% and heat losses by 26% compared to a reference roof.

Sound Insulation

Soil, plants and the trapped layer of air can be used to insulate for sound. Sound waves that are produced by machinery, traffic or airplanes can be absorbed, reflected or deflected. The substrate tends to block lower sound frequencies and the plants block higher frequencies.
A green roof with a 12 cm (4.7 inches) substrate layer can reduce sound by 40 decibels; a 20 cm (7.9 inches) substrate layer can reduce sound by 46-50 decibels.

The following benefits may be achieved, depending on the type and design of the green roof system (i.e., accessible/inaccessible, intensive/extensive, integrated with other building systems or not).

Economic Benefits

Potential to reduce the size of HVAC equipment on new or retrofitted buildings (capital and operational savings).
Potential to reduce the amount of standard insulation used.
Potential to incorporate cooling and/or water treatment functions.
Potential for local, regional, and national market exposure, depending on the uniqueness of the project.
Potential to reduce or eliminate roof drains.
Potential to meet regulatory requirements for stormwater management.
Potential to reduce community resistance to new developments.

Amenity Space and Aesthetics

Provision of amenity space for day care, meetings, and recreation;
Aesthetic appeal, increasing the value of the property and the marketability of the building as a whole, particularly for accessible green roofs. For example, American and British studies show that “good tree cover” adds between 6 to 15 per cent to the value of a home. Green roofs offer the same visual and environmental benefits.
Satisfying the aesthetic needs of people looking down upon the roof from adjacent buildings.
Potential to improve employee productivity.

Food Production

The Fairmount Waterfront Hotel in Vancouver used to grow herbs, flowers, and vegetables on its accessible roof, saving its kitchen an estimated $30,000 a year in food costs.

Costs

Although the initial costs of installing a green roof are greater than a conventional roof system, the long-term benefits and the energy savings outweigh the original investment (E.g. increased longevity of the roof and savings on energy expenditures). The costs of your green roof will depend upon the design of the green roof such as the type (extensive or intensive), climate, and plant selection. Depending on the green roof technology used initial cost for a green roof is:

Extensive green roof: $8 to $20 per square foot
Intensive green roof: $15 to 25 per square foot