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It's logical to assume that the quality control made possible by manufacturing components in a factory will make it easier to build high-performance homes. One company taking advantage of that is Unity Homes in Walpole, New Hampshire.
Unity builds zero-energy-ready homes from pre-insulated, closed panels that it makes in a 100,000 square foot, highly automated factory it opened last year in nearby Keene. The factory can crank out an average of 250 homes per year with a single shift of 20 workers. Unity hopes to eventually open more plants, and has been meeting with potential partners and investors in Colorado and in the Seattle area.
Founder Tedd Benson spoke about Unity's approach to offsite at the Alliance's Offsite Roundtable in November, and since then we have been looking for a chance to learn more. When we heard they would be hosting a Sunday open-house at a just-completed project—a net zero energy home with a rooftop PV system that should supply all of its energy needs—we decided to head up there for the weekend.
He was gracious enough to show us around the home and the factory, and to explain Unity's approach to design, engineering and manufacturing. This post takes a look at that approach; the next post will show how it helps Unity produce those high-performance homes.
Our readers will of course have differing opinions on how applicable Unity's products and business model are to the wider U.S. housing market. However we believe their experience offers valuable lessons, while showing some of offsite's untapped potential.
The key to success in the high-performance niche is knowing how to make super energy-efficient homes at market competitive prices. Engineering and panelization make this goal a lot more attainable.
Unity constantly optimizes its designs, products and processes. As a manufacturer they have embraced Lean production as a systematic way to eliminate waste in all its forms.
The constant improvement effort includes a key mindset shift. They think of homes in terms of systems and subsystems, and have configured all their processes around that way of thinking.
Although the company's website shows sample floor plans, they don't have standard models in the same way other builders do. Instead, they have standard spaces and systems that can be assembled in different ways.
For instance Unity's architects have created design "patterns" that consist of pre-configured floor plan areas. The software has access to hundreds of these, ranging from individual rooms to combinations like bedroom/closet/bath or bedroom/entryway. They yield thousands of possibilities.
Even the Port Orford Cedar screen porches on its homes conform to a strict pattern with three size choices: 12x12, 12x16 or 12x24. Posts are spaced to receive equally sized screens, windows or doors.
Benson compares his system to that used in kitchen industry, where all manufacturers make their products to fit a standard dimensional grid. That's why, for instance, you can use any dishwasher with any brand of cabinet.
Similarly, Unity's design components and patterns conform to an underlying 3D grid. They fit together according to pre-defined connection rules and include the engineering and product information needed to build them. Although he didn't go into more detail on the software (which was developed in-house over a period of years) it sounds like most of the spatial and product data needed for a home can be pulled from an underlying BIM database.
Unity's internal pattern language also helps grease the manufacturing process. This starts at the company's in-house design and engineering operation, where a "virtual fabrication" team preps plans for use by the machines in the plant. Using the same design patterns on different homes obviously speeds this process.
The team also sees to it that each home uses the optimal number of panels—basically as large as possible while still fitting on a standard flatbed truck—while ensuring that panels get manufactured and loaded onto trucks so that the field crew can unload them in the order they're needed.
And being able to make the same panels again and again for different projects obviously makes things more efficient on the plant floor.
An Evolving Process
While Unity makes all of its homes using closed panels, they are moving towards 3D modules in two areas: kitchens and bath.
The company is setting up part of the plant to make kitchen and bath "pods" that it can drop into place on the site. This makes sense because of the time saved by installing plumbing and fixtures in the plant. Benson is even talking with fixture manufacturers about branding them and could, for instance, offer a selection of Kohler baths.
Benson says that Unity's design and manufacturing systems have evolved gradually over several years, and that it has used lessons learned in his Bensonwood timber framing business (which he says is more complicated and difficult than panelizing). This evolution has happened at the same time the homebuilding industry has become more generally industrialized, with ever more prefabricated components (from prehung doors to manufactured stairways) being used on the jobsite.
He also acknowledges that offsite is far from monolithic, and that we should expect companies to move towards it on different paths and at different rates. What's not in question, however, is that the homebuilding industry will continue shuffling towards an industrialized future. Companies that want to get ahead of that trend could start by thinking more in system terms.
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