Green roofs have long been promoted as an easy and effective strategy for beautifying the building and increasing investment opportunity, especially in areas where outdoor space is limited. Condo associations have even started to implement green roofs and planter boxes for residents.
There are additional benefits to green roofs as well. They help to prolong waterproofing membranes of the roof by reducing wear and run off. Unlike typical roofs where water runoff is diverted into gutters, then into drains, sewage systems or into the surrounding soil, green roofs store some of the water into the substrate where it is held for use by plants. They can maintain approximately 70~90% of the precipitation that falls onto them.
Additional, unlike common roofs, they help to cool the building, extending HVAC systems. This is done by vegetation absorbing light, unlike black roof tops which directly absorb the heat causing a “heat island” effect.
See how popular green roofs are in Chicago. The City of Chicago’s Green Roof dataset and corresponding map provides the location, satellite images, and square footage of existing green roofs within the City of Chicago.
The information is derived from an analysis of high-spatial resolution (50cm), pan-sharpened, ortho-rectified, 8-band multi-sprectral satellite images collected by Digital Globe’s Worldview-2 satellite. The City supplied the consultant with a 2009 City boundary shapefile to determine the required extent of the imagery. Acquisition of three different strips of imagery corresponding to the satellite’s paths was required. These strips of imagery spanned three consecutive months and were collected in August 2010 (90% coverage), September 2010 (5% coverage) and October 2010 (5% coverage).
The results of the analysis include overall count of vegetated roofs, their total square footage, and the ratio of required to elective vegetated roofs. The study identified:
• 359 vegetated roofs within the City of Chicago.
• 5,469,463 square feet of green roof coverage.
The ratio of required vegetated roofs to elective vegetative roofs was 297:62 (~5:1). The median size of the vegetated roofs was calculated to be 5,234 square feet. Check the map below to see which neighborhoods have the most green roofs.