Not many zero-energy homes are available in the Portland market. But 11 more are on the way.

In Northeast Portland, design-build firms Green Hammer (construction services) and Birdsmouth Design Build (architectural services) are teaming up on a project being developed by Zach Parrish of Ono Development. Going Street Commons will include five single-family homes and three duplexes.

“Basically in every other case we’ve done there were major owner tenants or owners that were part of the process,” said Stephen Aiguier, founder and president of Green Hammer. “But this one is the first speculative that we’ve been a part of, and they are fundamentally different projects.”

In part, it’s a response to rising demand for highly energy-efficient homes.

“I think what’s kind of exciting is there are 11 zero-ready condos for sale,” Aiguier said. “They are like the other zero-energy buildings that we’ve done – they’re super insulated, they’re super comfortable. But we get calls all the time from people who are moving to Portland and they say, ‘I’ve got an $800,000 budget and I want a zero-energy home; what do you got?’ And I’m like, ‘We’ve got nothing.’”

But Going Street Commons, at 4905 N.E. Going St., in the Cully neighborhood, is poised to become the largest zero-energy-ready subdivision in Portland.

“When I bought the property three years ago I was going to be the developer and be the architect and do it all, including affordable housing,” said Josh Salinger, founder and CEO of Birdsmouth Design Build. “I wanted to prove we can build zero energy with cost parity, and even affordable housing. I wanted to prove the critics wrong.”

Ultimately, Salinger said, the project scope was beyond his company’s capacity, and projected costs precluded affordable housing. Zoning restricted development to 11 units.

“If we were able to build four more homes there, we could have driven the costs of these down,” Salinger said. “Zoning was the biggest prohibition. It would have worked with (Residential Infill Project rules) in place; it would have made a huge difference.”

To simplify design and construction, each home – whether in single-family or duplex form – will have the same 1,758-square-foot floor plan with three bedrooms, two and a half bathrooms and flexible attic space on a third level.

The barn-style homes will have black-stained larch wood siding and feature energy-efficient appliances. Each home will have a private yard with access to a shared green space and community garden, while a 5,000-gallon rainwater storage tank will provide irrigation for landscaping.

Earth Advantage platinum certification will be sought largely because the individual homes will not have pre-installed photovoltaic panels.

“We’re zero-ready on this one, so between the PV on the structures and then the other units we could get the whole community to zero energy,” Aiguier said. “But depending on your unit you could choose to add solar or allocate some of solar from the community space to your condo.”

When it comes to designing a zero-energy building, Salinger said, three key factors normally play a role: the site layout; surface area to volume ratio of the building; and the air barrier and building envelope.

“Maybe the most important thing is designing the air barrier in from the inception,” Salinger said. “Most of the energy losses in the home are lost to diffusion and leakage, so if we have a tight air barrier, which means very few penetrations, suddenly it has less risk of moisture damage, less mold, higher indoor air quality; you’re really controlling the air and it makes the buildings last longer and feel more comfortable.”

The surface area to volume ratio comes from a building’s shape. The most efficient shape in terms of heat loss is a sphere, which isn’t great for building design. A square is the next best bet, and for Going Street Commons, this concept was crossed with a Scandinavian aesthetic: a simple gable end design and long, flat walls and roofing.

“Boxes are not super compelling architecturally,” Salinger said. “But the Scandinavian vernacular has those gables, which turn those boxes into something compelling – and it’s something I think is beautiful. It has the low surface-to-volume ra

tio, and that’s how we came across that form and that vernacular.”

Going Street Commons’ building envelopes are an integral part of the design, along with four inches of EPS (expanded polystyrene) roof insulation and two inches of GPS (graphite polystyrene) foam-board foundation insulation, which exceeds code requirements. The rigid roofing insulation panels can even be removed from the building and reused elsewhere.

The flip side of the envelope is an efficient heating and cooling system. Each single unit – a combination of a heat pump and a heat recovery ventilator – is kept indoors with ductwork and venting set up to exit building walls instead of using a roof penetration.

One thing that really sets Going Street Commons apart is the use of a panelized wall system. The wall panels included stud walls, insulated sheathing, weather-resistant barrier and wooden battens upon which to mount exterior siding.

“Most of the battens were included with the wall panels,” Aiguier said. “The windows we actually just installed on-site; it was easier just putting them in right here. But our air barrier is super simple. There are no eaves on the building; it just wraps up and over. Transitioning from the walls to the ceiling can be a little bit complicated, so this makes air tightness super achievable.”

Green Hammer superintendent Greg Walton agreed and said the construction process has been relatively smooth.

“In a perfect world, if everything came out just how we wanted them, these buildings would go together in a day,” he said. “In this situation, the owner and developer worked directly with (the manufacturer) and we were a third party, so there were a lot of misses in general. But as a whole, it was really pretty seamless. There were little things that I attribute to a learning curve, but it went together pretty well.”

The building industry must do as much as it can to reduce greenhouse gas emissions, Salinger said.

“We have a moral obligation to our children and the planet to pay attention to these things because our industry is so impactful to the climate,” he said. “And when you do these things you make a building of much higher quality.”

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