GREEN ROOFING. What is Green Roofing ? A green roof or living roof is a roof of a building that is partially or completely covered with vegetation and a growing medium, planted over a waterproofing membrane. It may also include additional layers such as a root barrier and drainage and irrigation systems. Container gardens on roofs, where plants are maintained in pots, are not generally considered to be true green roofs, although this is debated. Rooftop ponds are another form of green roofs which are used to treat grey water. Green roofs serve several purposes for a building, such as absorbing rainwater, providing insulation, creating a habitat for wildlife, increasing benevolence and decreasing stress of the people around the roof by providing a more aesthetically pleasing landscape, and helping to lower urban air temperatures and mitigate the heat island effect. There are two types of green roof: intensive roofs, which are thicker, with a minimum depth of 12.8 cm, and can support a wider variety of plants but are heavier and require more maintenance, and extensive roofs, which are shallow, ranging in depth from 2 cm to 12.7 cm, lighter than intensive green roofs, and require minimal maintenance. ENVIRONMENTAL BENEFITS Green roofs are used to: - Reduce heating (by adding mass and thermal resistance value) A 2005 study by Brad Bass of the University of Toronto showed that green roofs can also reduce heat loss and energy consumption in winter conditions. - Reduce cooling (by evaporative cooling) loads on a building by fifty to ninety percent, especially if it is glassed in so as to act as a terrarium and passive solar heat reservoir – a concentration of green roofs in an urban area can even reduce the citys average temperatures during the summer - Reduce storm water run off A study presented at the Green Roofs for Healthy Cities Conference in June of 2004, cited by the EPA, found water runoff was reduced by over 75% during rainstorms. - Natural Habitat Creation - Filter pollutants and carbon dioxide out of the air which helps lower disease rates such as asthma - Filter pollutants and heavy metals out of rainwater - Help to insulate a building for sound; the soil helps to block lower frequencies and the plants block higher frequencies - If installed correctly many living roofs can contribute to LEED points - Increase agricultural space - With green roofs, water is stored by the substrate and then taken up by the plants from where it is returned to the atmosphere through transpiration and evaporation. - Green roofs not only retain rainwater, but also moderate the temperature of the water and act as natural filters for any of the water that happens to run off. Hope for a better living !!
Posted on: Mon, 05 Jan 2015 04:30:00 +0000
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