Green Roofs:

The City of Vancouver also has recommended through their proposal that the development should include a green roof strategy. A green roof is essentially a garden growing on top of a building. A green roof has a variety of benefits for the developer and the City. The benefits for the developer are that the green roof will reduce some of the need to heat and cool the building depending upon the seasons. The roof will also help in storm water management and enhance the biomass of the city.

A green roof consists of plants and vegetables growing on large roofs of buildings. This shifts the foot print of the building by changing the material used for roofing into a space with vegetation utilizing the roof of the building. Another important implication of the green roof is the absorption of storm water run off. The plants and soil absorb and transpire water. This reduces the amount of water that needs to be handled by the storm water and sewer system of the city. According to the Michigan State University the green roof systems can absorb up to 60-100% of the water that they receive. (http://www.hrt.msu.edu/faculty/Rowe/Green_roof.htm)

Green Roofs Have the potential to improve the visual impact for the residential neighborhood to the North. They can also provide habitat for various forms of wildlife such as birds and butterflies.

Heating or cooling requirements for buildings can be reduced by the use of green roofs or roof top gardens. In Europe green roofs are an accepted technology that have been used for twenty years. Green roof technology is very flexible and can be successful in both hot and cold climates. Green roofs have a variety of benefits both public and private, this section will limit it’s self to the benefits of green roof in regards to energy efficiency. There are two kinds of green roofs extensive and intensive. I suggest the extensive roof, which requires little maintenance and includes a few thin layers, and a thin lay of soil to support vegetation. The intensive roof has a thicker layer of soil that can support a variety of plants including trees.

A study by the Institute for Research in Construction conducted a study on roof tops, compairing the Heat flows of Green roofs to a reference roof. The institute found that Green roofs reduced heat gain by 95 percent, the reference roof lost 19.3 kWh/m2 while the green roof lost 0.9kwh/m2. The green roof reduced the total heat loss be 26 percent. As well as saving energy the green roof protects the roof from heat damage. Further, the more green roofs found in a city, the large impact they have on reducing the Urban Heat Island Effect. (Office for Energy Efficiency.)

This new product was difficult to research as the technology is still new and the chemical composition as well as adverse effects were unavailable, but by looking to the other example proposed by The City of Vancouver we can begin to understand that green products are not all what they claim to be. The Green Roof, which has been an alternative presented by other groups as well as this council as an alternative to alleviate some of the issues associated with the Urban heat island effect is the simplest method for explaining this dichotomy. This design is excellent at reducing the effect but how sustainable is the actual roof? It requires Styrofoam, 2 layers of hydrodrain and a monolithic membrane. Though the available chemical composition info is limited there is safety information available that states that when the monolithic membrane is applied, it is flammable and the fumes should not be inhaled during the process. These water proofing layers prevent the roof from leaking. They are also among some of the most unsustainable products available on the market. Styrofoam manufacturing was given the notorious tile as being the 5th largest creator of hazardous waste, due to the fact that 57 chemical byproducts are released in the production. When the earth is approaching peak oil, these products only seek to extract more of the limited finite resources that the earth has.