The people at Coho Construction call themselves “energy-efficiency geeks” — a label they’re proud of. Coho is a leader in green construction and remodeling for a city that itself is at the forefront of the American green building movement.

The O’Brien house in Portland’s Alberta neighborhood typifies that leadership. It goes beyond typical energy-saving measures like high-performance appliances and insulation.

Owners Mike and Vana O’Brien wanted a house that was as efficient and sustainable as possible. As a residential green building specialist with the City of Portland, Mike O’Brien had a lot of ideas. With help from Coho and renowned green architect Nathan Good, the O’Briens got a lot for their money.

Zero footprint, all electric
The 2500-square-foot home was built to be completely electric-powered so the O’Briens could sign up for renewable power/Clean Wind and make theirs a zero-carbon-footprint home.

The house has 7-inch-thick, strapped walls (a Coho invention) to minimize thermal bridging. It’s filled with sprayed-in, recycled cellulose insulation that’s non-toxic and fills cracks and crevices more efficiently than roll insulation.

Radiant heat for warmth
The earthen, radiant heat floors use warm water (partially heated by rooftop solar panels) to keep the house comfortable at lower ambient temperatures in winter, and cooler in summer.

These systems maintain an even winter temperature of 68 degrees on the main floor and 67 upstairs, without the need for an additional heat source, though the bedrooms do have radiant electric heaters to meet code requirements.

An open floor plan and a well-placed, open-able skylight allow the house to be cooled naturally on summer nights, while heat-reflective windows and the thick, insulated walls keep the house cool during hot summer days.

Efficiency integrated from the start
All this was planned using an integrated design process that coordinates efficiency designs in the most optimum combinations, which can help keep costs and hassles lower.

“Two energy-efficiency approaches may be great on their own, but can lose some of their benefits if combined with certain other approaches,” says Coho owner Adam Pushkas.

With the addition of energy efficient appliances and compact-florescent lighting throughout the house, the home earned an Earth Advantage® certification. According to Earth Advantage, certified homes must be at least 15 percent more efficient than standard homes, and usually have better indoor air quality, put less strain on the environment, and may even last longer. The O’Briens’ home uses about half the annual energy of a standard Portland home.

• Integrated design means fewer building hassles and more complementary systems
• Extra-thick, strapped wall system to reduce thermal bridging
• Wet-blown cellulose wall insulation (R-26) and R-49 attic insulation
• Extensive air sealing to limit/stop air infiltration and exfiltration
• Radiant earthen and concrete floors
• Coated windows to reduce heat gain
• Solar hot water heating
• Pre-wired for solar electric
• Pre-wired for air-to-water heat pump when available

• Typical Portland home: About 94 million BTUs (11,400 kWh of electricity and 550 therms of natural gas)
• O’Brien home: 48 million BTUs (14,000 kWh)

• Energy Trust of Oregon cash incentives: $1000
• Oregon Residential Energy Tax Credits: $1500
• Federal tax credits: $2000
• Net Cost: $2700

• Carbon-neutral home is better for the environment
• Monthly energy savings for homeowner
• Year-round thermal comfort
• Increased overall home value
• Pride in ownership
• Model for community
• Built with renewable resources, such as recycled-newspaper insulation, FSC-certified wood and re-used wood and materials