Study: New homes use less water than existing homes

SACRAMENTO – March 1, 2010 – According to a new study released today, new homes built to today’s standards use far less water than homes built 20 years ago and will use even less water when the California Green Building Standards Code comes into effect in 2011, making the retrofitting of existing homes even more significant in California’s efforts to reduce water use, the California Homebuilding Foundation announced today.

The study, Water Use in the California Residential Home, was prepared for the California Homebuilding Foundation by Stockton-based ConSol, a nationally recognized consultant on energy solutions for production single-family and multifamily builders since 1981. The study examined historical standards on water flow for shower heads, toilets, faucets and clothes washers, as well as water used for landscaping, and compared them to standards used today and those that will come into effect in 2011.

“The California Green Building Standards Code will be a win-win for the environment and for homebuilders,” said Gail Grimm, CHF’s Executive Director. “Homebuilders will be able to help protect water resources while offering more water-efficient homes to consumers without adding a significant cost to the price of the home.”

The study found that homes built in 2009 reduced indoor water use by 20 percent, saving over 15,000 gallons of water per year when compared to homes built in 1990, and that new homes built to the 2011 standards will further reduce indoor water use by 21 percent, saving over 12,000 gallons per year. The estimated cost increase for a new home to meet the 2011 standards will be $350 per home.

The study also found that landscaping accounts for 57 percent of total household water use, and that the California Department of Water Resources’ Model Water Efficient Landscape Ordinance will help save an additional 26,000 gallons of water per year.

“Combining the outdoor water savings with indoor water savings, a home built in 2011 will use 38,000 gallons of water less per year,” the report states.

Additionally, with new construction accounting for less than 2 percent of the total housing stock, older California homes represent an even greater opportunity for water conservation, according to the report. California currently has over 7.5 million single-family homes with more than half being built before 1980 when the first plumbing standards went into effect. Replacing shower fixtures on a home built before 1980 to be in line with the 2011 standards would result in over 22,000 gallons of water saved annually, while replacing a toilet with one in code compliance would result in additional water savings of over 16,000 gallons annually.

The report concluded that while there is still significant potential for water savings in new California homes, strategies must be developed to reach the existing housing stock in order to achieve deep statewide reductions in the amount of water used in homes.

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