Blue Roof - A new green roof

Blue Roof - A new green roof

In Australia, The idea of green roof was first introduced and install around 1930 (City of Sydney, Apr 2014). It has become a common feature in current buildings. Green roof refers to rooftop areas that are cover in soil and have vegetation

planted in. Green roofs have been noted as a sustainable feature in build environment due to the benefit it provides. In NSW, 30% of the roof area needs to be covered to count as a green roof (City of Sydney, Apr 2014).

In recent years, another form of the sustainable roof has appeared known as the blue roof. Blue roof is a roof that detains stormwater. It delays the drain inlets which create a temporary ponding. This design can delay the rate of storm water which reduces the pressure of the storm water drainage system of the city during heavy storms. Blue roofs are usually built along green roofs to provide water for vegetation (Justin McGar, 2015).

Fig 1. Blue Roof and Green Roof place on one roof

Blue roofs and Green roofs share some advantage such as reducing urban heat and reduce the heat gain of the building. It could result in reducing in electricity consumption due to the thermal benefit in summer. Blue Roof would cost less to build compare to the green roof also, it is lighter than the green roof. On the other hand, the green roof can create a biodiversity on the building and improve air quality during the day (City of Sydney, Dec 2014). Blue roofs are more popular in New York compare other places in the world (Justin McGar, 2015). I believe that blue roof would become beneficial for cities that suffer from monsoons weathers.

Fig 2.Section of Green and Blue roof

I think that the both roofs has their advantages which could contribute towards sustainability. I think that the collaboration of both ideas would provide a more sufficient. For example, blue roof with green wall. The load of vegetation and soil would be transferred from the slab to the façade of the building which allows the more load on the blue roof. The detention of storm water can be used for both watering plants and also be used for cooling system inside the buildings. It would still require further advancement in technology to achieve that level of efficiency. However, I think it would benefit develop cities to achieve sustainability from the idea of blue and green roofs.

Justin McGar. (July 2015). The New Green Roof is Blue. [Online] Sourceable. Available at: https://sourceable.net/new-green-roof-blue/[Accessed 12 March 2017].

City of Sydney. (April 2014). Green Roofs and Walls Policy. [pdf] City of Sydney. Available at: http://www.cityofsydney.nsw.gov.au/__data/assets/pdf_file/0011/200243/2014_126384__policy__green_roofs_and_walls2.pdf [Accessed 12 March 2017].

City of Sydney. (December 2014). Green Roofs and Walls. [online] City of Sydney. Available at: http://www.cityofsydney.nsw.gov.au/vision/towards-2030/sustainability/greening-the-city/green-roofs-and-walls#page-element-dload[Accessed 12 March 2017].

Fig 1. NYC. Blue Roof and Green Roof. [online]. NYC Environment Protection. Available at: http://www.nyc.gov/html/dep/html/stormwater/green_pilot_project_ps118.shtml

Fig 2. NYC. Blue Roof and Green Roof. [online]. NYC Environment Protection. Available at: http://www.nyc.gov/html/dep/html/stormwater/green_pilot_project_ps118.shtml