Building Performance in Bits and Pieces

A new wave of companies is assembling energy-efficient homes where it is always bright, warm, and dry.

The vast majority of residential construction follows a proven pattern that hasn’t changed much in more than a century. Pour a foundation, erect walls, pop in doors and windows, frame up rafters, nail on sheathing, insulate, add siding, plumbing, wiring, etc., and done!

But in British Columbia, a small group of builders are taking high-performance home construction to “the great indoors” and assembling extremely energy-efficient buildings—or pieces of them—inside shops and factories. The companies then either truck or barge the houses or components to a job site, where a crane lowers them into place, and a crew assembles them into a finished structure.

The approach is broadly called “off-site construction,” and it includes companies that produce prefabricated walls and floors, and those that sell complete plumbed and wired modular buildings.

[Tip: Scroll down for our off-site construction photo essay.]

As more communities begin referencing the BC Energy Step Code in their bylaws, and market demand for high-performance buildings begins to increase, off-site and modular construction companies may see a jump in demand.

Here are a few advantages that make this approach well-suited to the needs of high-performance buildings.

Improved Consistency

Inside an offsite-constrution shop, carpenters and trades have ready access to all their materials and tools. Crews move materials and completed walls around via an overhead gantry that lifts panels on and off assembly tables, dollies and, eventually, a flat bed truck.

“In the shop, all our tools are here, all the materials are here, and we’re working from a 3-D drawing; it is seamless. It’s still challenging, in a different way, but it is a really enjoyable experience,” says Rane Wardell, co-owner of Collective Carpentry, in Invermere B.C.

It’s the same deal for Metric Modular, formerly Britco.

“For us, it is all about standardization of practices, and you have a lot more consistency in a factory environment,” says Craig Mitchell, Metric’s director of innovative solutions.

“We have 93 quality-control check points in our factory, we check the details as the building modules move along.”

Climate Control

Off-site builders work in well-lit heated spaces, and carpenters do their thing at ground-level. There’s no dangling on a harness to tape up a joint between materials as the rain pours down around you. This is especially helpful in buildings built to the Upper Steps of the BC Energy Step Code, when the details really matter.

“When you are building on-site you are distracted by other factors, like weather, that can work against you,” says Rane Wardell.

“There’s no weather in the shop,” adds Matheo Dürfeld, CEO of BC Passive House, in Pemberton, B.C.

“We don’t have to carry boards up and down a job in ice and snow — we completely eliminate the impact of the elements on the material.”

Improved Materials Efficiency

Traditional builders will admit they head to the hardware store every other day or so. Off-site builders make that run once a week, or once a month.

“Everything is more thoroughly thought through,” says Collective Carpentry co-owner Jan Pratschke.

Matheo Dürfeld agrees. His team runs project drawing through an optimization program to produce a materials cut list. “With traditional on-site construction, waste is 15 to 20 percent, but with off-site can be as little 2.5 to 3 percent,” Dürfeld says.

Faster Construction Time

With off-site construction, a builder can be putting the components of a home together in the shop while concrete contractors are placing the foundation. “The approach is going to buy you a whole lot of time,” says Dürfeld.

The downsides? All three builders say the costs more or less balance out with on-site construction. The lead constraints are all transportation-related. Road restrictions restrict the size of completed prefab units to 16 feet by 70 feet. Off-site builders are also limited to locations where they can deliver units on a flat bed and crane them onto a site. They have to keep a careful eye on weight, to make sure they don’t max out crane capacity.

Still, it’s a proven approach for delivering high-performance buildings that will meet the requirements of the BC Energy Step Code.

“The more people that are building this way, the more we all benefit,” says Wardell. “We are all going to win.”

A Collective Carpentry worker blows cellulose insulation into a partly assembled wall panel. From a 3,000-square-foot factory in Invermere, British Columbia, the company builds precisely engineered wall panels destined for high-performance homes in British Columbia and Alberta.
Collective Carpenty’s crew cut precise tenons into these 8x8 Douglas Fir posts and 8x16 beams. Fitted into mortise joints, they now support the structure of a high-performance home in Squamish, B.C. The home likely meets the requirements of Step 4 or 5 of the BC Energy Step Code.
A worker wrangles a Collective Carpentry wall section on a project in Squamish, B.C. while a crane operator lowers it into place.
In this drone image of a Collective Carpentry project in Invermere, B.C., prefabricated wall panels, at right, await the crane operator’s tackle. He or she will swing them into position on the foundation, where the crew will secure them to the subfloor and one another.
The same Invermere home shown above, nearing completion. Note the thick walls, which support very high insulation levels. This home will likely meet the energy-performance requirements of Step 4 or 5 of the BC Energy Step Code.
Metric Modular recently completed this fourplex on the Yale First Nation, about 24 km up the Fraser Canyon from Hope, B.C. Metric Modular built it in its factory to the Passive House standard, which exceeds the requirements of Step 5, Part 9 of the BC Energy Step Code Photo: Metric Modular.
Metric Modular recenly completed this six-unit row house on the Yale First Nation. It is built to the Passive House standard, which exceeds the requirements of Step 5, Part 9 of the BC Energy Step Code. Each unit is 1,000 square feet. The per-unit heating bill, in the building’s first month of occupancy, in April 2017, was $7.
Metric Modular operates a 95,000-square-foot production facility in Agassiz, B.C., and a separate 100,000-square-foot factory in Penticton, B.C. The comany is now in the early planning and design stages on a social-housing project planned for Prince Rupert, B.C. It will consist of 40 units that will meet a Passive House level of performance, which would approximate the requirements of Step 5, Part 9 of the BC Energy Step Code.
A worker reviews a materials list on a job inside the Metric Modular plant in Agassiz, B.C. The company has five projects on the go, with three having to meet the requirements of the BC Energy Step Code.
BC Passive House works out of this 16,000 square foot factory in Pemberton, B.C., a mountain town about a half-hour north of Whistler. The company produces wall panels for high-performance homes that would meet the requirmeents of Step 5, Part 9 of the BC Energy Step Code.
The BC Passive House factory is built with glued-laminated Douglas Fir post and beam. The company designs and builds high-performance building panels, specialized structural panels, and heavy timber construction.
A sample wall cross section at BC Passive House reveals many of the details typical to high-performance construction, including increased wall thickness, cellulose insulation, an airtight membrane, and triple-glazed windows.
A worker walks in front of a set of completed wall panels, stacked horizontally inside the BC Passive House factory. The company is planning a 20-unit four-story passive house building, that will all be built off-site.

Glave Communications produced this post on behalf of the Training and Communications Subcommittee of the Energy Step Code Council, with resource support from BC Hydro. In an effort to increase awareness and understanding of the BC Energy Step Code, the Energy Step Code Council is sharing information on how and why builders and communities are using the new standard. Local governments may use the BC Energy Step Code, if they wish, to incentivize or require a level of energy efficiency in new construction that goes above and beyond the requirements of the BC Building Code.

BC Energy Step Code

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Sharing stories of how and why builders and communities are putting British Columbia’s energy-performance building standard to work.

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