The builders of tomorrow's homes are addressing a whole new reality: To be truly durable and sustainable, houses should be able to adapt to homeowners’ needs over time. Moreover, this adaptability must be achieved with minimal impact to the environment. But, how do you change a building industry that has held fast to conventional wisdom?

According to the Open Prototype Initiative (OPI), the answer lies in the open-built system of home construction. OPI is a program of the Massachusetts Institute of Technology House Research Consortium, Bensonwood Homes and other industry partners. Its goal is to improve homebuilding across the country and to make homes more affordable, adaptable and environmentally friendly. OPI has developed a process that makes it possible to construct thousands of environmentally friendly net-zero homes (which produce as much energy as they consume) and is sharing these innovations with the entire building industry.

“There are countless examples of green homes, but the industry has not developed a process to affordably mass-produce these homes,” said Kent Larson, director of the MIT House Research Consortium. “The Open Prototype Initiative has developed scalable processes, such as prefabrication and the separation of core services that, when followed, enable builders to create thousands of customizable net-zero homes that are being made more affordable right now.”

OPEN_1, the first house built by the OPI, uses green building concepts, such as energy-efficient wall, window, roof and lighting systems; advanced tracking of energy use; and provisions for the best possible indoor air quality. The design and construction processes of the open-built system demonstrate ways building assemblies can be fabricated off-site, with integrated systems for plumbing, heating and cooling, and exterior siding. Off-site prefinishing of construction elements allows for faster on-site assembly and thousands of pounds less of waste and debris.

The second home being built by the OPI, called “Unity House,” is the on-campus home for the president of Unity College in Maine. It was important to Mitch Thomashow, the president of Unity, a small school with an environmentally focused curriculum, that his home reflect the college’s environmental commitment. Designed for net-zero energy use, the 1,930-square-foot home will achieve U.S. Green Building Council Leadership in Energy and Environmental Design Platinum standards, feature a photovoltaic (PV) solar panel array and be a classroom for college students.

A key to the OPI, and one of the main elements that separates the home and the building process from other green or prototype home projects, is the use of open-built principles. Open-built thinking takes a layered approach to building, with each layer defined by its lifespan and anticipated need for future alteration. The homes resulting from this process are built rapidly and with minimal waste. Homeowners can easily move or remove walls and fixtures, access swiftly evolving technologies or adapt the home to the changing needs of the occupants.

For example, Unity House can be altered at its core, allowing walls to be moved or removed with the use of simple tools, rather than having to tear down Sheetrock. Preproduction in a controlled shop environment improves the quality of the home while reducing on-site waste. The average new homebuilding project today creates 8,000 pounds of on-site waste and can take from nine months to a year or more to complete. Goals for the entire Unity House project include producing less than three barrels of on-site waste and completing on-site construction in only 20 working days.