A Root Over Your Head: A Study of Green Roofs
The Case for Contemporary Green Roofs
In urban areas, rooftops account for 20-25% of horizontal surfaces. With so much otherwise unused space sitting nearly vacant, there is tremendous potential for positive development. Appropriately, these urban areas also tend to have the biggest need for sustainable interventions. The Urban Heat Island (UHI) effect describes the phenomenon where urban areas experience higher temperatures than surrounding non-urban areas. The surfaces created by cities, including streets, sidewalks and buildings absorb much more heat than natural surfaces formed from greenery. The added activity from higher populations, cars and infrastructure also generates more heat. UHI contributes to global warming and worsens both air and water quality. It also adds unnecessary additional strain to HVAC systems. All such symptoms of UHI can be substantially mitigated through the installation of green roofs.
Not only do green roofs help to cool down our cities, they also work to improve the air quality within them. Vegetation captures airborne pollutants, filters noxious gasses, and cleans the air through plant respiration. Buildings fitted out with green roof systems decrease HVAC equipment use. Using less heat and air conditioning saves money over the years. Using less energy also means there is less drain on power plants and the natural re-sources they depend on to operate. From the perspective of waste diversion, HVAC equipment lasts longer if it is used less. Roofing membranes will also have longer lifespans if included in a green roof assembly. These changes are not inconsequential when looking at how much waste is produced in big cities annually.