A home without a central heating system that's designed to reduce home heating costs by 75 percent or more is under construction.

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OLYMPIA — A home without a central heating system that’s designed to reduce home heating costs by 75 percent or more is under construction here.

It’s called a “passive house” — the first of its kind in the Olympia area and only the second in the state using an architectural design hatched in Germany 15 years ago.

The home achieves its high energy-efficiency rating through extensive insulation, airtight construction that eliminates heat loss, and a high-tech heat-recovery and ventilation system that maintains air quality.

In a passive house, a hair dryer, candle or coil from the water heater could be the heat source for the house, said Tessa Smith, home designer and co-owner of The Artisans Group, which designed and is building the home for DT and Kim North and their two sons.

Of particular interest to DT North was the 15-inch layer of expanded polystyrene that sits under the concrete foundation of the home, sealing it up from the bottom. “It felt like they were building an ice chest,” he said of the insulating qualities of the foundation.

The kitchen, dining area and living room, all interconnected and called the “great room,” will feature extensive, south-facing windows to capture solar heat passively. The house is being built so some solar-power units can be tacked on, if desired.

The house is under construction next door to the Norths’ older, energy-inefficient home. Their plan is to tear it down and salvage as much of the building material as possible for reuse.

Smith estimates it’s about 7 percent more expensive to build a passive house compared with one built to code. But the energy savings should make up the difference in about 4.5 years.

The Artisans Group has two other passive houses under construction and 12 projects in various stages of design and permitting, Smith said.

Olympia lead building official Tom Hill said the home’s ventilation and heat-recovery system met the code requirement for a heating system. “We understood this is an unusual heating system, so we required they set aside room for a backup system, if it’s needed,” Hill said.

Simple enough, Smith said. The home is designed to include a heat pump, if necessary. But no one involved with the project expects to need one.

“There’s plenty of hard data to show that passive houses perform as they’re designed to,” DT North said. “It’s basically conventional construction with some specific design features.”

One of those features is heavily insulated interior walls wrapped with an exterior shell. “It’s like a house within a house,” Hill said.