Building Green: Water Conservation

Reducing water consumption and protecting water quality are key objectives in sustainable building. One critical issue of water conservation is that in many built areas, the demands on the supplying aquifer far exceed its ability to replenish itself. That is why, to the maximum extent feasible, "green" buildings should increase their dependence on water that is collected, used, purified, and reused on-site.

There are a wide number of strategies for water conservation. To start, waste-water may be minimized by utilizing water conserving fixtures such as high efficiency, ultra-low flush toilets, water-saving sinks and low-flow shower heads. In the landscape, reducing the amount of turf grass and landscaping instead with trees, hardy shrubs, and indigenous, drought-resistant plants will significantly reduce water consumption, as will utilizing low-flow sprinkler heads and optimized irrigation schedules and controls.

In addition to water efficiency measures, sustainable design can also include water re-use. The two most common methods of water recycling are rainwater harvesting and gray water use. Rainwater harvesting is the technology used to collect, convey and store rain for later use. It is an important green building strategy, contributing towards credits in both the LEED™ standard and Built Green™ program. Rainwater is considered the cleanest form of harvested water and can be used for toilet flushing, hose bibs, industrial applications, domestic clothes washing, irrigation, landscape water features and more.

"Active" systems for harvesting rainwater use pipes, tanks and pumps for collecting, filtering, storing and recycling water that would otherwise be sent to municipal sewer or storm water systems. These are differentiated from passive harvesting systems which detain rainwater in vegetated swales, rain gardens, green roofs or permeable pavements so that it can infiltrate naturally back into the soil.

Above: The wood clad Canada Pavilion designed by Cirque du Soleil and built by Canadian engineering and construction company SNC-Lavalin Inc. for Shanghai World Expo 2010. In keeping with its theme "The Living City: Inclusive, Sustainable, Creative", the pavilion's exterior wall is covered by evergreen seedlings that collect rainwater and channel it to a drainage system. Harvested water is recycled for use inside the pavilion. Take a virtual tour.

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