In the Dawn Creek neighborhood of Lancaster, California, 60 miles north of Los Angeles, KB Homes, one of the nation’s largest home builders, is addressing the climate risks of drought, extreme heat, and water availability with the construction of “double-zero” single-family homes—double zero because they use zero energy and zero fresh water for irrigation. A model for the future, the double-zero home is designed and constructed to produce within a year as much energy as it uses through technology such as photovoltaic (PV) solar panels and enough water to irrigate the landscape through an on-site graywater recycling system.
In California, where years of historic drought have led to stringent water restrictions and where future water shortages are more likely, markets have started to focus more on water use. KB Homes has been “looking at ways to be more water efficient over the long term to increase resilience,” says Thomas DiPrima, president of urban operations for the company’s Los Angeles Ventura division. “How do we make water go further, how do we reduce the cost of water, and how do we make homes where the landscape fits the local conditions?” Another factor in KB Homes’ double-zero approach is that in 2006 California passed AB32, one of the world’s most progressive laws to address climate change. The law requires the state to reduce carbon emissions from energy and other uses to 1990 levels by 2020 by increasing energy efficiency in buildings, expanding the use of renewable energy technology, and reducing waste, among other strategies.
By lowering energy and water use, KB Homes’ Double ZeroHouse addresses anticipated climate risks while reducing a home’s impact on the environment. A graywater recycling system is expected to recapture and reuse between 40,000 and 70,000 gallons of water annually for a household of four. The system by Nexus eWater collects and cleans drainwater from showers, bathroom sinks, and washing machines for subterranean yard irrigation. The Dawn Creek home also features cutting-edge water-conserving technologies, offering homebuyers a WaterSense®-labeled home with advanced plumbing, drought-tolerant landscaping, and smart irrigation. The dishwasher uses 33 percent less water than other highly efficient dishwashers by reusing water from the final rinse cycle for the pre-rinse cycle of the next load. WaterSense®-labeled bathroom faucets, toilets, and showerheads and a motion-sensing kitchen faucet help save more water.
With all of its water-efficient elements, the home is estimated to conserve up to 100,000 gallons of water annually for a household of four or more when compared to a typical resale home; for landscaping, the home is estimated to reduce water use by approximately 70 percent compared to the resale home. A real-time meter allows homeowners to track water use. “If we have the ability to daily or weekly look at our water use, we have the ability to change our habits,” says DiPrima, who would like to see meters that would inform consumers of costs as well as amount of water used.
The Double ZeroHouse has been certified by the U.S. Department of Energy (DOE) for meeting all of the energy efficiency requirements of the DOE Zero Energy Ready Home program (see facing page). To be certified, a home must meet the energy and durability requirements of Energy Star Certified Homes Version 3, the insulation requirements of the 2012 International Energy Conservation Code (IECC), and the indoor air-quality and water-saving requirements of the U.S. Environmental Protection Agency’s Indoor airPLUS and WaterSense programs. The home must have PV solar panels installed or have the conduit and electric panel space in place for them.
Ranging in size from 1,773 to 3,206 square feet, the Double-ZeroHouse homes employ a range of systems and features to reduce the homes’ energy use. All feature a built-in home energy-management system that allows homeowners to track energy use remotely from a smartphone or tablet. The system can be expanded with optional upgrades such as smart thermostats, lighting controls, and Internet-connected door locks. Smart appliances can be programmed to run energy-intensive tasks at off-peak hours. Electric vehicle charging stations are another optional upgrade. The homes are super insulated with advanced framing techniques and materials. A high-efficiency tankless hot-water heater also supplies heat for the home, and all of the lighting is LED based. “We don’t install LED lights in a home only because they save energy,” says DiPrima. “We look at other factors, such as longer-term maintenance and lower cost. LED bulbs may last the life of the home.”
Dawn Creek home prices range from the high $200,000s, depending on design. KB Homes estimates it costs an additional $48,000 over conventional design and construction for appliances and water-heating and cooling systems that support resilience, not including discounts and energy-tax incentives. Projected annual energy savings compared to a home built to the 2009 IECC standards are $2,698 with PV panels and $361 without, so savings can quickly offset the extra construction costs, which are financed over the life of a mortgage. DiPrima says KB Homes has been able to reduce the cost of a net-zero home by developing more efficient technologies and working with trade partners to improve installation methods, and KB is looking for more cost efficiencies. “By cutting costs, we are putting buyers back in the market,” says DiPrima, adding that homeowners are more likely to stay in their homes when they have fewer surprises and know what energy costs will be.
By lowering energy and water use, KB Homes’ Double ZeroHouse addresses anticipated climate risks while reducing a home’s impact on the environment.
Consumers have shown interest in net-zero homes, he says, although the four- to five-year timeline needed to recoup investment after tax credits and incentives has deterred buyers who are unsure how long they will stay in a home. Financing structures could be doing more to drive demand: mortgage lenders now require a home to be finished and certified before a “green loan” is approved, DiPrima says, and solar production does not always appear to be adequately valued by many appraisers, even though it greatly reduces energy costs. The Double ZeroHouse has received significant local, national, and international media coverage— at an estimated advertising value of more than $7.1 million—in addition to interest from municipalities, nonprofit organizations, and the general public. If adopted throughout KB’s portfolio, the influence of the Double ZeroHouse would be significant. In 2013, KB Homes delivered 2,179 homes in its West Coast region, which includes all of drought-prone California.