This article was originally featured on our sister site BUILDER.
Water efficiency is a great example of getting “two for one.” Saving water also saves energy, which means not only energy savings for the community but also more overall dollar savings for home owners. A recent study by the UC Davis Center for Water-Energy Efficiency found that the statewide water restrictions California Governor Jerry Brown mandated in 2015 had the unintended benefit of saving energy. In fact, the electricity saved from decreased water consumption equaled the impact of all of California’s major utility energy efficiency programs combined!
In keeping with this trend, the Greenbuild KB Home ProjeKt is a model for high magnitude—yet effortless—water and energy reductions through smart design strategies. In this innovative home project, KB Home collaborated with partners from business, design, and academia to create a space that satisfies the aesthetic and resource needs of today, tomorrow, and the future. The result is a home designed to earn LEED® Platinum status and the U.S. Environmental Protection Agency’s (EPA’s) WaterSense® label, meeting rigorous criteria for water efficiency.
The ProjeKt’s water-efficient products and technologies deliver savings with satisfaction. WaterSense-labeled plumbing fixtures manufactured by Kohler meet the EPA’s criteria for both water efficiency and performance. The toilets use only 1.0 gallon of water per flush, and the bathroom faucets flow at 1.2 gallons per minute, both exceeding the EPA’s water efficiency criteria.
In the kitchen, the ENERGY STAR® certified KitchenAid dishwasher reuses the final rinse water, and is 33% more efficient than other models on the market. Additionally, a Rinnai tankless water heater includes an on-demand re-circulation pump, which prevents hot water waste for the home and saves precious time for the home owner. The shower and laundry drains are isolated to allow for greywater reuse in toilets—or potentially for a yard. Rainwater harvesting was also built into the ProjeKt’s design.
Each of these water-saving features translate into quantifiable energy reductions, amplifying the benefits of water efficiency—or, getting “two for one.” To understand the precise relationship, the ProjeKt team worked with WaterSense to model the impact of a standard new home and the impact of the ProjeKt home with its advanced technologies and features.
A typical home similar in size to the KB Home ProjeKt (1,600 square feet and two bedrooms) in Los Angeles (location of the model’s premier at Greenbuild) with a typical landscape, uses more than 110,000 gallons of water a year. Every gallon of water has a specific energy signature depending on its end use. Water used outdoors requires energy to transport, treat, and deliver potable water but does not require energy to heat or treat wastewater like a clothes washer or shower head. All water requires energy, leading to an associated total energy use of more than 3,400 kilowatt-hours (kWh) per year for similar homes to meet the home’s water supply needs.
When compared to a typical home of a similar size, the Greenbuild KB Home ProjeKt would save more than 20% in water and consume less than 2,300 kWh per year—more than 1,200 kWh per year saved just by managing water efficiently.
Where do all these savings come from? The specific mix of sources for its potable water supply and the energy required to deliver water influence the baseline amount of energy a home uses. As a WaterSense labeled home, an occupied KB Home ProjeKt could use less than 90,000 gallons per year, saving 200 kWh annually on water delivery.
Plus, the Greenbuild KB Home ProjeKt’s improved hot water distribution and reduced demand from WaterSense-labeled and other high-efficiency products could help save nearly 1,000 kWh per year, or 41% of the energy used to heat water compared to a typical home. A larger home in a cooler climate would consume far more energy and hot water, making the savings potential even higher when the ProjeKt's features are applied.
With the Greenbuild KB Home ProjeKt as a model for new homes, think of the possibilities these types of water and energy reductions could have for communities in the near future. For more information on the KB Home ProjeKt, visit www.builderonline.com/kbhomeprojekt. For more information on EPA’s WaterSense program, visit www.epa.gov/watersense.