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to homes built prior to 2003 and at least Analyses of Efficient 10,000 gallons per year less than compa- Development rable new homes built at the same time. As demonstrated in But the claims would be unproven until Graph 1, WSHs showed homes had been occupied for several years, the lowest mean annual allowing real data to be analyzed. consumption (93.8 In 2010, with a large sample of WSHs built, kgal/yr) and statisti- SNWA analyzed water use among different cally had the lowest classes of homes. Four groups of homes average consumption of were analyzed: all groups. Homes built in the 1990-1995 and • Water Smart Homes (WSHs; n=1,675); 2000-2003 timeframes • Homes built between 1990 and 1995 had identical demand (predominantly pre-dating federal profiles, and the statisti- water efficiency standards; n=34,989); cally highest use (185.6 kgal/yr). Non-labeled • Pre-drought code homes built between homes built in the same construction year as sq. ft. respectively), and post-drought code 2000 and 2003 (n=44,323); the WSHs exhibited an intermediate level of homes built in the same period as WSHs • Post-drought code, non-branded consumption (115.5 kgal/yr) that was statis- having an intermediate mean (5,670 sq. ft.). homes built in the same period as tically differentiated from the other groups. Lot sizes thus paralleled annual use. Like- WSHs (n=22,798). wise, the distributions of lot sizes within Review of lot sizes revealed large differ- For each group, water use was analyzed for ences among the study groups, with WSHs groups did not match across groups. 24 months in the calendar years 2007 and having the smallest lots (4,537 sq. ft.), Recognizing that lot size is a significant 2008, with averages for these years used for traditional and pre-drought code homes confounding variable, reselection to norm- means. having the largest lots (6,983 and 6,900 alize lot size was done by selecting a sub- Continued on page 16 www.ca-nv-awwa.org 15


SOURCE Summer 2012
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