In sustainable building circles, much emphasis has been placed on carbon “footprint” calculations: tallying up the energy consumption and emissions from carbon based fuels such as oil, gasoline and wood. With drought conditions escalating in many parts of the US, many in building and construction are now turning an eye to “water footprint” calculations to anticipate and reduce the consumption of water in home construction. The water footprint includes both water use after the home is completed and water used to manufacture and produce the elements that go into a building.
We spoke with Sara Cederberg, Technical Director, LEED at United States Green Building Council about the impact that water footprints can have in building. “The concept of a water footprint has solidified in recent years, including an industry ISO standard for water consumption in building.” From a production standpoint, Cederberg said the largest consumers of water are the production of steel and concrete. In particular, the production of cement, the binding agent for aggregate and other ingredients for concrete, is a big consumer of water to cool the clinker materials after being fired in a 1400-degree kiln.
She added that as a building material, wood compares very well in the water footprint assessment. Trees filter and purify water, while stabilizing the groundwater and aquifer. The species Katahdin uses for its log home production, Northern White Cedar, is even lower on the water footprint scale since it replenishes naturally without the need for tree farming or cultivation, which can be high water-consuming operations.gree
Another way to consider a building product’s impact on water is to look at its end-use when replaced. Asphalt shingles are some of the most common products used on houses. Asphalt shingles can have a reduced effect on the aquifer if they are recycled rather than disposed at a landfill. Metal roofs are often made with recycled materials, and offer a benefit of easier rainwater collection.
Cederberg also offered other materials that may result in high water use in initial application. Granite countertops or dressed stone use water-cooled machinery to shape, but their long-term lifecycle assessment may indicate a smaller water footprint than a composite product made of petroleum-based plastics. Another consideration includes evaluating some products that are made from highly sustainable crops-corn or cotton- but that require high water consumption to grow.
We located several places where you can calculate your water footprint, which can be particularly enlightening. Here are two options: The Change the Course program through National Geographic and the Water Footprint Calculator, which offers an opportunity to try some new water-saving methods and check for improvements later on. USGBC’s LEED for homes has made an impact on more than 150,000 units positively rated for sustainability. For more information on LEED click here.
Read about this family’s LEED Gold Katahdin log home.