Green roofs are not a new thing, seeing as how sod was used as roofing in the middle ages, but they are making a new and improved comeback. Besides just offering the possibility of some refreshing greenery in what may be an otherwise bleak city landscape, green roofs do carry many practical and environmentally friendly uses. Installing grass on the roof requires less upkeep than a normal roof and lowers electricity bills. A green roof absorbs rainwater, reducing overflow, and also absorbs sunlight during the summer to lower heating costs. It insulates the house against temperature and sound, and counteracts urban heat island effect.
Read the full article here: Plant a Green Roof: Feed 70 Chickens and Lower Your Bills