The efficiency of those fixtures and fittings, however, only accounts for the difference in flow rates between conventional and low-flow products; they also are tested at a water pressure that is far higher than the real world, thus overstating the potential savings, according to Craig Selover, director of plumbing product technology at Masco R&D. In addition, the bulk of the bathroom efficiencies (about 12 gallons per capita, or 80%) are achieved by using high-efficiency toilets alone.
That’s because water use at faucets and showers, even with flow restrictors that result in some measure of savings, is more a function of lag time—that dead zone spent waiting for hot water to reach the showerhead or lav faucet not calculated in a flow-rate-only comparison. Lessen lag time, and the water savings really kick in at those locations. (See “Go With the Flow,” page 23, for more on fixtures.)
Systems Approach. Reducing lag time means rethinking the home’s hot-water delivery scheme. A centralized water heater, shorter (and insulated) pipe runs, and a closed-loop configuration for recirculating hot water to selected taps combine to hasten hot-water delivery and reduce waste.
Basically, a dedicated closed-loop line for hot water is fitted with a pump activated by occupancy sensors or manual switches or buttons in the bathrooms to more quickly replace the cold water standing in the pipes with hot water; if a sensor or switch is activated upon entry into the bathroom, hot water may already be waiting at the shower or faucet by the time the user calls for it.
And, by looping back to the water heater, a recirculating system also helps save energy. “The flow back into the water heater [to replenish the tank] is warmer than the city water supply,” says Alec Nord, an associate project manager at Uponor. That results in lower heating demand for an appliance that accounts for an estimated 20% of a home’s energy use.
Perhaps most important, hot-water recirculating systems arguably hold the key to selling the value and investment in water savings to an ambivalent buying public. “Convenience and satisfaction are the main concerns for homeowners compared to the amount of water they can save,” says Selover, who directed a research project that found a 30% drop in shower water consumption among the households tested with low-flow products and recirculation pumps.
Elsewhere Indoors. Among the other water-using fixtures, fittings, and appliances within a home, only upgrading the clothes washer results in sizeable savings.