This article about green roofs
and roof agriculture in Boston makes a great case:
“A roof farm is a type of green roof. A green roof is a system of layers that is laid over an existing roof. A green roof is beneficial to a building owner and the community because it protects the existing roof, doubling to tripling its life, thereby saving money and keeping materials out of the landfill. Green roofs also reduce a building’s energy costs by insulating in the winter and cooling the rooftop in the summer. Combine these benefits with green roofs’ ability to temper the effects of two common urban environmental problems – combined sewer overflow and the urban heat island effect – and you have a waste-eliminating, resource-protecting, CO2-reducing, food-producing powerhouse of a concept.”
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