It’s May and the swallows are in flight over the largest green roof in the City of Philadelphia.
Philadelphia is known worldwide for more than just cheesesteaks and Rocky Balboa. The Philadelphia Art Museum, the award winning Green City, Clean Water’s program and even the PECO green roof garner interest and respect beyond the city line, and for good reason.
Nine million gallons of water – that’s how much stormwater the PECO green roof has managed since it was planted in December of 2008. Over one acre of succulent plants (planted in 3-inches of light weight media) function as a green infrastructure work horse. The highly engineered green roof media captures at least 60% of the rain that falls on the roof, storing it in the root zone. The massive network of groundcover plants soak up this rainwater reserve and ultimately evaporate the excess water into the atmosphere. This process, evapotranspiration, is the mechanism through which green roofs cool the rooftop atmospheric temperature and protect the city’s waterways from combined sewer overflows and damaging erosion from high storm runoff flows. Rainwater, drainage, roots, evapotranspiration – Brilliant!
The environmental benefits of green roofs in urban environments are legion, but the visual impact of a landscape on structure – the view offered to the surrounding buildings – is a benefit that cannot be measured but should not be understated.
The PECO green roof is being maintained by Roofmeadow Services, Inc., launched by Roofmeadow earlier this year.
The deeper beds and planters host a selection of native perennials some of which are just ready to open and start a green roof bloom show.