A key design objective of the green roof of the Ballard Library in Seattle was the opportunity to generate community interest in green design by making the facility a dynamic teaching tool for sustainable design and environmental awareness. The library was designed by Seattle-based architect Bohlin Cywinski Jackson. Landscape architect Swift & Co. (Seattle), plus contractor PCL Construction Services (Bellevue, Wash.) and green roof consultant Rana Creek Habitat & Restoration (Carmel Valley, Calif.) also worked on the project with American Hydrotech Inc. (Chicago), who recently earned a Green Roof Award of Excellence from Green Roofs for Healthy Cities for their development of a green roof for the Ballard Library project.
One of the most significant components of the garden roof assembly is the water retention/drainage/aeration element. The element is comprised of lightweight panels of 100 percent recycled polyethylene, molded into specially designed retention cups and drainage channels. The design allows for the free drainage of excess water, achieving flow rates significantly higher than that of conventional drainage methods, while simultaneously promoting irrigation through capillary action and evaporation into the soil/vegetation level.
The green roof consists of a waterproofing membrane, insulation, and drainage/moisture retention elements, which are part of a Garden Roof Assembly, all supplied by American Hydrotech.
Some of the additional notable environmental benefits of this roofing project include:
- Reduces energy costs.
- Increases roof longevity.
- mproves water/stormwater management.
- Serves educational and research functions (for example, the Seattle City Light Green Power Panel provided 17 solar panels for the green roof, and will monitor the amount of electricity captured and collected onsite. Additionally, various rooftop sensors measure wind speed, direction, sunlight, etc. Artists created computer generated artwork for the library using this collected data).
- Uses recycled/reused materials (primary components contain recycled content; recycled carpet, glass, ceramic and ceiling tiles are also used throughout the building).
- Preserves biodiversity.
- Requires minimal maintenance.
- Conserves water.
The Ballard Library is yet another example of the city’s Sustainable Building Policy, spearheaded by Mayor Greg Nickels in February 2000. The policy’s stated goal is for all capital improvement projects over 5,000 square feet—new or renovated—to meet the LEED silver standard. Awarded a 2006 Institute Honor Award for Architecture by the AIA, Ballard Library serves as a model for future projects in this region.
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