OPEN Building Principles

One of the cornerstones of the OPEN Prototype Initiative is Open Building, developed in part at MIT by John Habraken who headed MIT’s Department of Architecture from 1975 to 1981, and embraced by Kent Larson, who currently heads MIT’s House_n Consortium and Open Source Building Alliance.

These principles have been further refined and expanded on by Tedd Benson, founder of Bensonwood Homes of Walpole, New Hampshire. Bensonwood has been involved with Open Building techniques for nearly three decades. The Open-Built® systems that Bensonwood has developed during the past decade currently represent the state-of-the-art of Open Building in America.

Open Building "layers" the home, disentangling components to create greater access for updating its configuration and/or services. This can extend the useful lifespan of a house from decades to hundreds of years.

"...We are prototyping the future of homebuilding."

The concepts of Open Building provide a framework for a better way to build. The Open-Built® components, assembled to create the first OPEN Prototype (OPEN_1) at Crotched Mountain, represent a unique and ground-breaking expression of Open Building in America. The systems and components will not be perfect, but that is what makes prototypes so educational and useful. We will apply the lessons learned on OPEN_1 to the design and construction of OPEN_2, and in this way refine and accelerate the process of constructing homes in the US. We believe that we are prototyping the future of homebuilding.

The Open Building approach provides many advantages to the design/build process for all the OPEN Prototype projects. These include:

Design for Flexibility

The systems and components in the OPEN Prototype have been designed to accommodate changing uses and needs. This is particularly important for the initial occupants of OPEN_1, some of whom are recovering from brain injuries. As these occupants redevelop their physical and cognitive abilities, the home will evolve with them.

With multi-use buildings such as OPEN_1 and OPEN_2, that serve both as residences and public buildings, the function of the building changes--sometimes very quickly. The ability to make larger scale modifications relatively easily, is important. Interior partition walls have been configured in a way that they can be “uninstalled” and moved. The task of turning two bedrooms into one, or making a living room into a larger entertainment area, becomes a straightforward operation. The de-mountable baseboard provides access to wiring chases in the walls, should outlets or data ports need to be changed or added. The easily-removed ceiling panels provide access to repair or modify plumbing, heating, and ventilation systems.

Disentanglement of Systems

Open Building views the home as a collection of layered systems. The layers we identify include the site, the structure, the skin, the space plan, the services, and the “stuff” within the home. Keeping these layers separate, and disentangled, allows us to create systems using materials appropriate to their expected life spans. Access to the system, commensurate with the need for future modification, is designed into the initial plan.

Like the plumbing and electrical systems, the HVAC (heating, ventilation, and air conditioning) system is designed into specific spaces that do not interfere with the building’s structure or skin. The backbone of this system, which is not expected to change significantly over time, will be built of long-lasting materials preinstalled in a central mechanical core wall. The branches of this system are accessible within the Open Built® ceiling system, allowing for service or modification, should the layout of the home be changed.

Delivering Prebuilt Systems to the Site

The Open Building principle of integrated systems is best expressed in a production process that involves off-site fabrication of finished components that are delivered to the site, and then assembled quickly and efficiently.

Prebuilding components in the controlled conditions of a production shop makes sense for many reasons. Working conditions in a shop are more predictable than on job sites subject to weather and seasons. The quality of materials and workmanship can be assured. Computerized numerically-controlled (CNC) machinery can be incorporated. Jigs and fixtures can dramatically improve production efficiency.

Bensonwood’s Open-Built® process was particularly advantageous for the first OPEN Prototype, OPEN_1, built at the Crotched Mountain Rehabilitation Center (CMRC). The brief construction time on site — thirty working days — minimized the disturbance to CMRC’s campus and to its inhabitants, some of whom are especially sensitive to noise and dust.

Planning Inclusively and Building Virtually

Open Building maintains that everyone involved in the design and construction of a building is in a position to contribute to a successful outcome. By involving the major stakeholders and the key subcontractors in the planning process, we are able to optimize the performance, appearance, and value inherent in the OPEN Prototype projects. We are also minimizing the potential for the conflicts that are common on a typical construction site—conflicts about time, space, and quality during the construction process.

The lead designers spend many hours meeting with the clients to ensure that the OPEN Prototype projects serve the intended needs. Bensonwood’s project steward team provides expertise in project management. They coordinate meetings with the electrician, the plumber, the HVAC subcontractor, and others, to discuss how and when the systems will be installed. Much of this work has been facilitated by sophisticated 3-D modeling software.

Designers create the architectural drawings that include site details and seasonal variables (topography, solar exposure, and shading). Engineers can feed their information--snow loads, wind variables, and weights that determine structural materials and sizing--into the modeling software. Wall panel and roof panel systems are planned and added to the design, along with interior and exterior finishes. The subsystems are designed and included in the process, with direct input from the individual subcontractors. Once the total design is complete, a virtual three dimensional model is visible.

This process produces a very high quality end result--timbers, panels, and subsystems in place and ready for on site assembly.