Sustainable building.....Water Efficiency

Water conservation and efficiency programs have begun to
lead to substantial decreases in the use of water within buildings.
Water-efficient appliances and fixtures, behavioral
changes, and changes in irrigation methods can reduce consumption
by up to 30 percent or more.7 Investment in such
measures can yield payback in one to three years. Some water
utilities offer fixture rebates and other incentives, as well as
complimentary water surveys, which can lead to even higher
returns.
As Figure 1 reveals, for a typical 100,000-square-foot office building, a 30 percent reduction
in water usage through the installation of efficiency measures can result in annual
savings of $4,393. The payback period is 2.5 years on the installed conservation and efficiency
measures. In addition to providing a 40 percent return on investment, the measures
result in annual conservation of 975,000 gallons of water.
As demand on water increases with urban growth, the economic impact of water conservation
and efficiency will increase proportionately. Water efficiency not only can lead to
substantial water savings, as shown in the above example, it also can reduce the requirement
for expansion of water treatment facilities. Non-residential water customers
account for a small percentage of the total number of water customers, but use approximately
35 percent or more of the total water.8 More information on water conservation
programs and incentives can be obtained from your local water utility, or by calling
Water Wiser, a national water-efficiency clearinghouse of the American Water Works
Association and the U.S. Environmental Protection Agency, at 800/559-9855.

WATER EFFICIENCY
in a Typical 100,000 sq. ft. Office Building
Water Usage
Number of Building Occupants 650
Water Use per Occupant per Day 20
Total Annual Building Water Use (gallons) 3,250,000
Total Annual Building Water Use (HCF*) 4,345
Water Cost
Water Cost per HCF $1.44
Sewer Cost per HCF $1.93
Total (water + sewer) Cost per HCF $3.37
Total (water + sewer) Annual Cost $14,643
Savings
Initial Cost of Water Measures** $10,983
Annual Water Conservation, at 30% Reduction (HCF) 1,304
Annual Water + Sewer Savings (1,304 HCF at $3.37) $4,394
Payback Period 2.5 years
*One hundred cubic feet (HCF) = 748 gallons
** Measures include efficient, low-flow appliances and fixtures
as well as control sensors.
Source: Figures based on communicat ions with Water
Department specialists in San Diego, Phoenix, and Sacramento.