Roof design has made major strides where sustainability is concerned. Changing the roof to become a more dynamic component of the building is a critical part of green design.

Roofing Materials

Selection of roof materials for a green building involves health, environmental, and energy considerations.

The available materials have pros and cons. Coal tar and gravel, for example, can be produced from recycled materials, whereas EPDM roofing is made from virgin materials.

LEED provides a listing of roofing materials with their environmental impacts that can be helpful in making selections.

Green Roofing Approaches

Some green roofing approaches include:

• Using light-colored roofing materials to reduce the thermal gains by reflecting solar heat.
• Using recycled or recyclable material (such as shingles manufactured from slate dust)
• Using material that has a longer life (such as metal or polymer roofing systems).
• Using a protected-membrane roofing system, which allows reuse of the rigid insulation during future reroofing, substantially reducing material use.

Some roofs have become a resource as well as a shield. Rain can be collected by a roofing system connected to a cistern (collection tank) so that the water can be used for other purposes.

Living Roofs

Living roofs, or "green roofs," involve a waterproof membrane applied on a roof deck, covered with earth that will grow grass or other vegetation.

This strategy provides insulation, alleviates runoff and helps to meet the impervious surface requirements on some facilities so that more building can be accomplished with less land. Living roofs also generate oxygen, causing a net reduction in a facility's CO2 generation.

This article is an excerpt from the book Green Building: Project Planning & Estimating which can be purchased through the RSMeans Bookstore.

This new 2nd edition has been completely updated with the latest in green building technologies, design concepts, standards, and costs. Includes Means' Green Building CostWorks CD at no additional cost.

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