Why is this site sustainable?

• Vegetated roof surfaces capture and treat precipitation falling on the building roof, which protects local waterways
• The layers of soil and plants act as an insulating layer in winter and decrease the cooling demand during the summer
• Demonstrates a solution to urban heat islands
• The plantings require no irrigation and very little weeding
• Riverstone ballast lines the perimeter of the roof, which slows and directs stormwater runoff to storm drains

 NWC Green Roof Construction and Function

• Riverstone ballast on perimeter of roof slows the flow of stormwater runoff.
• Vegetation covers 2,786 ft² of the 4,072 ft² roof (68%).
• The roof is planted with four cultivars of Sedum species for a varied and more interesting appearance. There are equal distributions of Sedum Album‘White Stonecrop’, Spurium ‘White Two-Row Stonecrop’, Spurium ‘John Creech Two-Row Stonecrop’, and Ternatum ‘Wild Stonecrop’.
• The soil and underlying substrate is designed to capture the moisture and slow the flow of stormwater runoff.
• Excess runoff from the green roof runoff infiltrates through French drains, which were sized to infiltrate twice the required volume of the 1- and 2-year storm.

Resources reviewed: ppt. presentation on Cornell green buildings, BSN ppt. on, USGBC website, “Green Building Tour Tips and Techniques,” Final LEED review report. (should add link)