California-based KB Home has long had its eye on the year 2020, when the state’s zero net energy standard will go into effect, requiring all new homes to produce as much energy as they consume. Now, the production builder is taking the long view on another pressing environmental concern: water conservation.
It recently put the finishing touches on a demonstration home that is as water conserving as it is energy efficient. The Double ZeroHouse is filled with water-sipping devices the company hopes to make available to buyers in the near future, including graywater recycling and a first-of-its-kind water-reusing dishwasher. Company leaders aim to make this level of high-tech energy and water savings replicable on a large scale and attainable to average home buyers.
“Our goal would be by end of year to get this system to where it can be mass produced in our homes,” says Tom DiPrima, KB’s executive vice president for Southern California. Additional costs for such a sustainable home would be about $3,000 to $4,000 with a return on investment of two to three years—critical for many home buyers. “I hear from consumers all the time that if they can get it paid for in a couple years, they’re in,” says DiPrima.
Company officials estimate that the model home, located in the Dawn Creek community in Lancaster, Calif., will conserve 150,000 gallons of water a year when compared with a typical resale home, a reduction of approximately 70 percent. In addition, the house is designed to produce as much energy as it consumes, for an estimated $4,452 in energy and water savings annually.
Extreme Water Savings
Practically unheard of in a production environment, the home’s graywater recycling system from Australian company Nexus cleans water from showers, sinks, and the clothes washer and stores it in an underground collection tank. It is then held until it is needed to irrigate the lawn and garden. The chemical-free system can handle up to 200 gallons a day.
Residents won’t have to worry that the tank might run dry: When occupied by a family of four, the home will produce up to 40,000 gallons of graywater a year—more than enough to irrigate the drought-tolerant landscaping. Unlike untreated graywater, the Nexus system treats the water so it can be stored indefinitely until used.
KB planners also focused on reducing water heating costs, a top energy cost in a typical California home. A Power-Pipe heat exchanger located in the garage wall near the shower drain stack recovers up to 46 percent of energy in waste hot water. This energy is extracted and used in the home’s tankless water heater, helping to preheat incoming cold water. “It makes the tankless heater work far more efficiently,” says DiPrima.
In addition, a water-recycling Whirlpool dishwasher uses 33 percent less water than other highly-efficient dishwashers by saving water from the last rinse cycle for use in the first pre-rinse cycle of the next load. Other cutting-edge products on display include an EV charger for electric and hybrid vehicles and a compressed natural gas fueling station for natural gas powered cars, real-time monitoring systems to track water and energy usage, and a “smart” refrigerator that shifts energy-intensive functions to off-peak electricity hours.
The Path to Net Zero
KB Home has worked for years to bring net-zero technology to mainstream buyers, says DiPrima. Although its first net-zero home added $100,000 to the cost of the house, KB has cut that amount in half in less than a decade. “We’ve been working with our trade partners on how to build more efficiently, to get labor hours out,” DiPrima says. The Double ZeroHouse was built in 30 days from trench to furnishing.
Company officials also realized that they could minimize the need for pricey solar panels if their houses were well insulated and extremely energy efficient. Thanks to superior insulation and air sealing, which yielded a 42 HERS rating, the Double ZeroHouse is powered solely by a 7 kW SunPower solar system, making it net-zero energy. “What we learned is that you have to reduce before you produce—you have to reduce the electrical load before you talk about producing energy,” DiPrima says.
Another technique shown in the house that works well in warmer locales is moving ductwork out of the attic and into the conditioned spaces of the home. This cuts down on the work that an air conditioner must do to cool the house. “It’s all about making homes affordable to buy and maintain,” DiPrima says. “First-time buyers are the core of our business, so we need to keep our homes affordable.”