Our mission is to make Philadelphia the greenest city on earth by providing free green roofs to the citizens of our beautiful city.
Benefits · Reduces the urban heat island effect · Increases roof life span · Reduces storm water run off · Filters pollutants and CO2 out of the air · Filters pollutants and heavy metals out of the rainwater · Increases wildlife habitat in built-up areas · Reduces heat loss and energy consumption in the winter · Reduces sound pollution · Adds property value
Urban Heat Island Effect The urban heat island effect is the difference in temperature between urban areas and the surrounding countryside. In large cities this can as much as a 5oC difference between the city center and the rural environs. Urban areas have large areas of hard reflective surfaces. This is referred to as the albedo effect. These surfaces absorb solar radiation and reflect this heat back into the atmosphere. Any reduction in this effect can have a positive effect on smog and airborne particles in the atmosphere. Roof areas are a significant part of urban hard surfaces. Plants on green surfaces absorb heat and then use it through evapotranspiration. Green roofs therefore would play an important role in reducing urban temperatures, and subsequent improvements in air pollution/smog, as associated with the albedo effect. Extended Roof Life A green roof system protects the waterproofing membrane from climatic extremes, UV light & mechanical damage and in so doing almost doubles its life expectancy. Therefore a good quality root resisting waterproofing system with a normal life expectancy when exposed to the elements of 30 years, can be expected to last up to 60 years, thus saving the client the cost of re-waterproofing during the average buildings expected life time. Green roofs store rainwater in the plants and growing mediums and evaporate water into the atmosphere. The amount of water that is stored on a green roof and evaporated back is dependent on the growing medium, its depth and the type of plants used. In summer green roofs can retain 70-80% of rainfall and in winter they retain between 25-40%. Although green roofs are recognized as playing a positive role in improving air quality, this is linked to the positive effect they have on the urban heat island effect. Individual roofs in themselves will not have a great effect. However a large areas of green roofs in specific areas of large cities or in Air Quality Management Zones would have a noticeable effect. Green roofs have a positive effect in terms of thermal insulation through their ability to cool buildings and insulate them during the winter Noise and sound Insulation The combination of soil, plants and trapped layers of air within green roof systems can act as a sound insulation barrier. Sound waves are absorbed, reflected or deflected. The growing medium tends to block lower sound frequencies whilst the plants block higher frequencies.The amount of sound insulation is dependent on the system used and the substrate depth. Contact us at greenroofphilly@gmail.com or check out our myspace at myspace.com/greenroofphilly |