Dean Kahn

Ultra-green Bellingham house needs no city water, sewer service

Dan Welch and his son, Ezra Welch, 2, walk in front of their new energy-efficient house in Bellingham on Thursday Feb. 11, 2016. The house recently won the “Best Building Science” award from Green Builder Media.
Dan Welch and his son, Ezra Welch, 2, walk in front of their new energy-efficient house in Bellingham on Thursday Feb. 11, 2016. The house recently won the “Best Building Science” award from Green Builder Media.

At this point, Dan Welch and his family are comfortable with the idea of people visiting their home to see how it was built and to peer at its heat pump, water filtration system and other inner workings.

People visit because the Welch home is like no other in Bellingham. It’s the first modern house in the city to not be hooked up to city water and sewer. Instead, two large tanks gather rainwater from the metal roof. The water is then cleansed for use in showers, baths, drinking and cooking. And the two bathrooms have composting toilets.

Those are just a few of the many features included to make the house a net-zero water and net-zero energy residence. There’s so much advanced technology and design that the house recently won the “Best Building Science” award from Green Builder Media. Judges called Welch’s house “the ‘moonshot’ of green building.”

While there were some bumps along the way, he was paving the way for everybody else.

Rose Lathrop, Sustainable Connections

Welch is the founder of [bundle] design studio, in Bellingham. His business focuses on new construction and remodels with the environment in mind.

His goal with his 2,000-square-foot, three-bedroom, two-bath house was to construct a residence as close possible to the Living Building Standard, which promotes energy efficiency, waste reduction, sustainable materials and wise land use.

“It’s the goal of my business and that’s the goal of this project,” Welch said. “‘Best Building Science’ gives what I’m doing as a business some legitimacy.”

From the get-go, Welch used his house as a case study to educate people about advanced ways to build sustainable houses, and to experience the bottlenecks that can come with a cutting-edge project. Sustainable Connections, in Bellingham, included the house on its home tour last year, and organized tours and workshops.

“This gave other builders and other designers the chance to come and check it out to, see how things performed,” said Rose Lathrop, green building and smart growth manager at Sustainable Connections. “While there were some bumps along the way, he was paving the way for everybody else.”

Welch said he’s happy to share what he knows and what he experienced, because it can help foster more green construction in the future.

“It’s much easier to develop green projects if you know how to do green projects,” he said.

Building a living lab

Welch, 39, grew up in Boise, Idaho, and earned a master’s in architecture at the University of British Columbia. He started [bundle] design studio so he could be his own boss and adjust his work schedule to accommodate life with his family; his wife, Ashley, a teacher; and their three young children, ages 4, 2, and 2 months.

Welch knows his Birchwood house, overall, won’t appeal to many clients. It costs more than a standard house, and not everyone is thrilled with the idea of managing their own household water system and composted human waste.

Invest in your building first, and everything else secondarily.

Dan Welch, [bundle] design studio

But he wanted to build, and live in, what amounts to a living laboratory of green technology.

Welch says people who aren’t ready for the full package on display in the Birchwood house should focus on the important basics of green construction: a well-oriented, airtight and well-insulated building, with smart and energy-efficient energy, heating and ventilation systems. Those features are expensive to retrofit later, while it’s easier and more affordable to later install solar panels, expensive finishes, top-end lighting, and other environmental features.

“Invest in your building first,” he said, “and everything else secondarily.”

Special monitors are tracking the house’s temperature, humidity, power use, water use, and level of volatile organic compounds (chemicals that can harm people and the environment). The information is being gathered by the Northwest Energy Efficiency Alliance to help develop standards for eco-friendly houses.

Welch couldn’t afford every green material and device that he wanted, due to expense and regulations. But the house is still packed with innovative practices.


Key to efficient heat is a well-designed house and building envelope. The long, narrow shape of Welch’s house offers southern exposure to every room, with triple-pane windows providing lots of light and natural warmth.

The walls and ceiling have extra, high-quality insulation, and the house is built airtight. To handle moisture inside the house, outside air is drawn into “dry” rooms — such as bedrooms and the living room — and stale air from “wet” rooms — the bathrooms, laundry room and kitchen — is vented outside. The two flows of air pass through a heat-recovery ventilator, where heat in the outgoing air is used to warm the incoming fresh air.

The house is a field test for a heat pump that uses carbon dioxide instead of other refrigerants that are less efficient and more harmful to the environment. The heat is used for domestic hot water and for warmed water that flows through pipes in the concrete flooring for ambient warmth. Welch said the house is the first in North America to use the heat pump for both purposes.

Contractor for the house was Chris Tretwold, at Tretwold Construction, in Bellingham.


The house has energy-efficient appliances and lighting, and solar panels soon will be installed.

The Welches don’t have a clothes dryer. Instead, they dry clothes outside in good weather, and their laundry room has space for hanging washed clothes.

Welch said they usually do laundry at night and hang the wash to dry before going to bed. The clothes are usually dry by noon the next day, he said.


Welch used materials that are salvaged, low maintenance and sustainably produced.

Joists in the house are beams salvaged from the old Birchwood Elementary School, and rafters, cabinet faces, shelving, handrails, decking and stairs also were built from the same salvaged lumber.

Countertops are made with pressed recycled paper, and the exterior, with metal siding and cedar boards, is low maintenance, with space for moisture to evaporate.

A green roof with plants is low maintenance and extends the life of the roof above the sun room.


The compost toilets eliminate the need to hook up to city sewer, but Welch said he’s not happy with the model of toilet allowed by health department rules. Better toilets are readily available in other countries but have not been approved by the health department, he said.


Welch had hoped to filter waste domestic water in the several feet of dirt and gravel in the sun room. So far, the city hasn’t allowed him to do that, he said.

Household water comes from rainwater collected from the metal roof and piped to two large water tanks behind the house. Each plastic tank holds up to 5,000 gallons.

Water from the tanks flows through two sediment filters and a carbon block, and is then exposed to ultraviolet light to kill microorganisms. Tests confirm the water’s purity, and it tastes great, Welch said.

“It’s better than city drinking water,” he said.

Dean Kahn: 360-715-2291

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