Washington-Based zHome Sets National Net-Zero Precedent

Builders seeking a net-zero energy home showcase can look to BuiltGreen’s zHome townhome complex in Issaquah, Washington.

White paper released

According to a BuiltGreen white paper, the zHome development is the first net-zero energy townhome complex in the US, a project meant to spur the market toward deep green housing for the average person.

Built Green is an environmentally friendly, non-profit residential building program of the Master Builders Association of King and Snohomish Counties.

When launched. this project set some impressive environmental benchmarks, including net zero energy use:

• a 70% reduction in water use
• a 90% construction recycling rate
• using only low- and non-toxic materials among other specifications
• zHome achieved its benchmark of net-zero energy and releases excess energy to the grid

When construction was furnished, all zHome units eventually sold at slightly above standard prices for the time and area, despite going “on the market at the tail end of the Great Recession.”

End results several years later

“Happily, based on utility data, we have found that zHome achieved its benchmark of net zero energy,” concludes the whitepaper, adding zHome is currently producing 3.5% more energy than is consumed.

“Over a two-year span, the eight units for which we have data and the community trellis generated an excess 562.8 kWh of renewable energy for the grid on top of what zHome consumed. When the net energy use is instead calculated on a rolling annual basis, zHome still comes out positive, producing an excess 160 kWh per year on average.”

The company does point out that homeowners who practiced energy conservation helped make this achievement possible. Energy efficiency aside, the report states the highest consuming zHome unit only uses 759 kWh per month, significantly less than the Issaquah average of 838 kWh.

According to BuiltGreen, interviews with homeowners confirm that adapting to zHome life “necessitated getting used to new technologies and involved a learning curve.” These home owners also appear to support the idea of green living.

The bottom line is that this, the country’s first Net-Zero Energy townhome complex, meets expectations on reducing energy and water consumption, according this newly released white paper. Here are some of the findings:

1. Over 562.8 kWh was generated above what zHome consumed, and was put back onto the grid between April 2013 and April 2015.
2. zHome exceeded net-zero energy by 3.5 percent, or almost $54 worth of electricity.
3. PV arrays range from 4.8 kW to 7.2 kW and performed 24 percent better than modeled.
4. The goal of reducing water consumption by 70% was achieved. The average zHome per capita daily consumption was 16.07 gallons from the utility and 11.46 gallons of rain water.
5. zHome is built from recycled, reclaimed and FSC-certified wood materials. Everything inside the home is low- or non-toxic.
6. All zHome units sold at slightly above standard prices for the time and area.

In 2011, zHome was built in the Seattle suburb of Issaquah, Washington by a private developer, Ichijo USA, in collaboration with the City of Issaquah and Port Blakely Communities, which provided a site for both affordable housing run by the YWCA and the zHome project. Additional partners included Puget Sound Energy, the Washington State University Energy Office, and King County.