Green Roof Case Study Aileen Winquist Environmental Planner Arlington County, Dept. of Environmental Services

Green Roof at 2100 Clarendon Blvd In 2003, as part of the County’s lease renewal, negotiated with the building owner to retrofit a 3,200 sq ft section of roof. Roof needed to be replaced. Received a grant from Virginia Dept of Conservation and Recreation (DCR). Grant covered $34,000 – about half the cost of the roof.

Green Roof at 2100 Clarendon Blvd Worked with Building Owner, Charles E. Smith, and Architect, Page Southerland Page. Demonstration Project - education and tours. Environmental benefits – stormwater mitigation, building insulation, urban heat island mitigation, and aesthetic improvement.

Green Roof at 2100 Clarendon Blvd Conducted structural engineering analysis to make sure building structure could hold weight of saturated soil. The existing ballasted roof (stone) was about the same weight as the green roof. Planted with six types of sedum. Installed October 2003.

Insulation Layer Reused styrofoam insulation that was on roof.

Water Barrier is most important part of the roof, and is installed the same way as for a standard roof. No Leaks! Water Barrier

Waterproof Testing After waterproofing, store 2 inches of water on the roof for 48 hours to test barrier.

Root Barrier Root barrier is thick plastic, and prevents roots from penetrating the waterproof layer.

Water Retention Root barrier sealing and water retention layer. Water retention layer stores water in small “cups” for use by plants after rain event.

Soil Placement Install filter fabric beneath soil, so not to clog water retention layer. Specially engineered, highly inorganic soil (very little humus) with high water absorption capacity.

Soil Layer Spread soil to consist depth – 3 inches.

Wind barrier Cover soil with photo- degradable wind barrier to prevent wind erosion.

Planting the Roof Plant through the wind barrier with sedums, low- lying, hardy, water-retaining plants that thrive in harsh environments. Select several varieties based on blooming, color, etc.

Planting Complete October 2003

One year after planting September 2004

Green Roof May 2005

Arlington County’s Green Building Programs Site Plan Projects must have: LEED accredited professional; LEED scorecard; LEED tracking; Construction waste management; Energy Star appliances (for multi-family projects).

Green Building Programs Commercial Incentive program – density bonus. Green Home Choice program – for residential projects. Twenty projects currently underway or completed. County projects – evaluate feasibility of meeting Silver LEED standard.

Langston Brown School and Community Center – Opened 2003

Other projects with green roofs Walter Reed Community Center (under construction); Fire Station #5; Palazzo Condominium (NFWF grant).

Questions? Aileen Winquist