Thoughtful Design Is the Key to Reducing Home Water Use

March 22, 2016
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May/June 2016
This online-only article is a supplement to the May/June 2016 print edition of Home Energy Magazine.
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Product selection and home design can have a dramatic impact on residential water use at minimal cost and effort. In California, for example, no matter what El Niño brings, water conservation will continue to be a hot-button issue. What can smart home builders and remodelers do to make a dent? Embrace new technologies and thoughtful design. 

Low-flow showerheads and toilets, which have long been championed by government agencies, are useful tools, but they don’t address the home as a system. In order to make real progress on water conservation, we have to move away from a piecemeal way of thinking about residential water use to a systemic approach that not only conserves water but also recognizes the connection between water and energy use. Builders and developers are in a position to effect change by incorporating water- and energy-efficient systems right into their home designs. 

The bathroom has an especially big impact on a home’s water and energy use. Showering alone is responsible for almost 17% of a home’s water use, according to EPA estimates. A poorly designed water distribution system wastes a surprising amount of water (as much as 6 gallons per day) just waiting for the heat to arrive. What's more, the amount of wasted hot water—water that's heated but not used or is used after it's cooled off—has been calculated at nearly 11 gallons per day. 

Here are five accessible technologies that builders and developers can incorporate into a home’s water system in the design stage without necessarily spending more on the project. Incorporating any of these technologies into a home design will not only become increasingly important environmentally but will save your clients more money as new energy calculators are developed that take these technologies into consideration.

WaterSense Showerheads

Customers sometimes complain that pressure and temperature fluctuate with low-flow showerheads, but the new generation of WaterSense-labeled showerheads address this issue admirably. Integrated flow regulators allow the showerhead to maintain the same flow rate over a variety of water pressures, all but eliminating pressure and temperature fluctuations. The best showerhead designs deliver nearly identical flow rates within the typical pressure range of 40–80 psi. On top of that, according to EPA, the average family could save 2,900 gallons per year by installing WaterSense-labeled showerheads.

Thermostatic Shutoff Valve

A thermostatic shutoff valve, which may be integrated into or installed behind the showerhead, lets cold water flow when the shower is first turned on, and then slow to a trickle when hot water (> 950F) arrives. You’ll know that the shower is hot when water stops flowing; just pull a cord to turn the flow back on. 

Recirculating Control System

A simple pump that sits under the sink at the water outlet farthest from the water heater cuts down on the cold water that is wasted before hot water even arrives—and gets hot water to you faster. Turn it on, and the pump sends the cold water that’s sitting in your pipes to the water heater. The pump turns off when the water heats up and allows the hot water to flow at the tap or shower.

Drain Water Heat Recovery System

DOE estimates that 80–90% of the heat energy that a water heater adds to water goes down the drain. That energy, which could be used to reheat more water for use in the shower, dishwasher, or clothes washer, can be captured through a drain water heat recovery system installed in the drain itself. Some of the heat from the departing water is transferred to cold water through a conductive copper coil that preheats the cold water before sending it back to the water heater.

Structured Plumbing

When thoughtfully included in the design process and correctly executed, manifold plumbing systems—control centers for hot and cold water—are a tidy way to distribute hot water efficiently. Manifold plumbing systems can be centrally located at the point where the water service line enters the building. Each water line is dedicated to an individual fixture, saving both energy and water by optimizing hot-water distribution. A manifold plumbing system takes planning, and the designer and builder must collaborate with a plumber. But imagine telling your customers that if they buy your home, they’ll never have to wait for hot water again. 

Build It Green's GreenPoint Rated program is in the process of developing a new energy savings calculator that will incorporate water efficiency and drain water recovery into its rating system. These will also be addressed in the California Energy Code, Title 24.

RESNET is in the lead nationally, recognizing that water saving as an important aspect of home performance. Builders will soon see the benefit of incorporating more-efficient water systems into their projects. Forward-looking builders and developers can see savings on both the front and back end. A systemic approach to water distribution will reduce water and energy use, eliminate behavioral and structural waste, and contribute to the comfort and well-being of home buyers by delivering exactly what they need, when they need it.

Amy Dryden is the senior program manager at Build It Green, which administers the GreenPoint Rated Green Home Building certification program in California. She is also the technical services manager for multifamily energy efficiency programs. She may be reached at amy@builditgreen.org.

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