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Net-zero living: Liberty Lake house will generate enough electricity to offset residents’ energy use

UPDATED: Tue., May 1, 2018, 9:58 a.m.

Imagine living in a house that produces enough kilowatts of electricity to offset your energy use.

Solar panels on the roof generate power. Ultra-efficient appliances cut down on energy consumption. The home’s design and construction also help it achieve a “net-zero” energy rating by reducing the need to run a furnace or air conditioner.

Last year, Greenstone Homes built its first net-zero home in Liberty Lake’s Rocky Hill neighborhood. The net-zero concept – producing enough electricity onsite to meet the occupants’ needs – could be the future for homebuilding in the Spokane area.

“I think there will be a day when almost every home we build may be net-zero,” Jim Frank, Greenstone Corp.’s founder, said of his company.

California is already headed there. By 2020, all new residential construction in the Golden State must be net-zero.

In the Inland Northwest, Frank predicts that net-zero home construction will follow market demand. The Greenstone home, which is open for tours, helps show people how a net-zero home operates. It also lets the company gauge interest and get feedback from prospective customers.

About 2,500 members of the public have been through the net-zero home, which was finished in August and featured in the Spokane Home Builder Association’s tour.

“Technology is starting to drive a lot of changes in the homebuilding business,” Frank said. “Customers are looking for some new things, and we’re experimenting with them.”

The all-electric house is priced at $315,000 and will eventually be sold. The residence is a compact, 1,167 square feet, featuring three bedrooms, two bathrooms, a great room, kitchen and a double-car garage with extra storage space.

Greenstone officials declined to reveal how much the net-zero home cost to build compared to conventional construction. However, if the residence was built to local building code requirements, the annual electric bill would be about $1,000, according to the company. Instead, it’s zero.

For environmentally conscious buyers, the residence has another perk: The solar power is carbon free.

In Washington, about 5 percent of greenhouse gas emissions come from residences. (Transportation and energy sectors are the largest emitters.)

The Greenstone house is certified as “net-zero ready” by the U.S. Department of Energy. During a third-party audit, the house earned a negative score on the Home Energy Rating System, generating more electricity than it uses.

The rating system “is like your golf score,” Drew Benado, Greenstone’s home building division manager. “Lower is better.”

Behind the number

The net-zero concept starts with the home design and construction. To keep out winter drafts and summer heat, the Rocky Hill house features rigid foam insulation, a tight shell and high-performance windows.

“You can have a house like a windbreaker or a house like a parka,” Benado said. The insulated, airtight parka approach requires smaller furnaces and air conditioners for heating and cooling.

To keep the air fresh inside the house, there’s a system that vents stale, contaminated and moist air outside and brings new air in. The system is sophisticated enough to detect a build up of carbon dioxide in bedrooms from people exhaling while they sleep, Benado said.

“When we had the fires last summer – with all the smoke and ash – the air quality was much higher inside than outdoors,” he said.

Power from the sun

Ninteen solar panels generate electricity for the house. Side-by-side meters at the back of the house track power production versus energy use. Residents can also log-in to their computer to see what’s happening.

When the solar panels produce more electricity than residents are using, the homeowner will get a credit from Avista Utilities, said Mary Tyrie, an Avista spokeswoman. The credits can be banked until the end of the year, when regulations require the account to be zeroed out, she said.

Avista acts as a backup electric source for the home when the residents use more energy than the panels produce, and after the sun goes down.

Next Gen Electric of Coeur d’Alene provided the solar panels for the Greenstone Home. Regardless of the size of the system, most of solar installations achieve payback within six years, said Miranda Hoefert, who owns Next Gen Electric with her husband, Adam.

The payback time includes the effect of federal tax credits, she said. In addition, Washington residents can get an incentive for using solar panels made in the state. Idaho residents are eligible for a state income tax credit.

The eventual development of solar-storage batteries will be a game changer for residential systems, Frank predicted. Most solar power is generated between 11 a.m. and 3 p.m., yet home demand for electricity peaks in the late afternoon and evening. The ability to store solar energy for use at peak times will make it more valuable, Frank said.

And in the event of an extended power outage, such as in the wake of the 2015 windstorm, people would have backup systems, he said.

Appliances play role

Energy-efficient appliances contribute to the Greenstone home’s net-zero rating. The dishwasher, refrigerator and washing machine in the house are Energy Star rated to reduce electricity use.

Newer dishwashers also use less water, said Rick Hurd, the store manager for Fred’s Appliance Design Center in Spokane Valley, which sold the appliances to Greenstone. Newer machines use four to seven gallons of water per load compared to seven to 12 gallons for an older machine.

Energy Star washing machines also cut down on energy and water use, Hurd said. Sensors determine how full the machine is and adjust the amount of water added to each cycle. Higher spin speeds extract more water from the fabrics, so the clothes require less time in the dryer.

The house also features LED lighting and low-flow faucets. And the paint and flooring were chosen based on low emissions of chemical compounds.

“This is an evolving area,” Frank said of net-zero home construction. “I do believe that demand will grow as people start to understand the return on investment.

“Ultimately, we hope it drives down the operation and maintenance costs on a house,” he said.

This story was updated on April 30 to indicate that Next Gen Electric installed the solar panels for the net-zero home. Northwest Renewables, which was in the original version of the story, has installed solar panels in other Greenstone homes.


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