California Center for Sustainable Energy

Architect designs modular housing with sustainable, eco-design

When architect Michelle Kaufmann and her husband Kevin Cullen, a general contractor, looked into purchasing their first home in the San Francisco area, they weren’t happy with what they found. Many of the features they wanted – natural lighting, cross ventilation, open spaces, natural materials, energy efficiency – just weren’t available at a price they could afford. So they decided to build their own home, not setting out to be green, but ending up creating a modular structure that has since become a model for sustainable prefabricated homes.

Kaufmann drew a standing room only crowd during a lunchtime lecture held June 1 at CCSE, during which she outlined her quest of striving for simplicity at a moderate cost. At Michelle Kaufmann Studio, they prescribe to five basic principles of for sustainable building: smart design, use of eco-materials, energy efficiency, water conservation and healthy environment.

“If green homes are only for the elite, then we won’t succeed in creating sustainable communities,” Kaufmann said. “Everybody should be able to have a green house. For it to be accessible, it has to be cost-efficient and easy.”

She explained that once her original home, called the Glidehouse® was built, people began asking if they could have one too. That’s when inspiration struck: What if the homes could be mass produced in a factory and assembled on site?

The first Glidehouse, with three bedrooms in 1,566 square feet, is a net-zero energy house that aligns the rooms in a single row with an outdoor patio that runs the length of the structure. It has a high-performance envelope using structural insulated panels, floor-to-ceiling glass walls on the south side, lots of natural materials and a slew of energy efficient electrical and HVAC systems. Kaufmann and Cullen built it themselves with subcontractors, on site, in about 14 months.

By taking the design into a factory, Kaufmann was able to build a nearly identical prefabricated version in just over four months and at a cost about 20 percent less. Some of savings came from reduced construction waste, which Kaufmann estimated at 50 to 75 percent less than built on site. The prefab house was built in modular pieces that could be shipped by truck with sections often already outfitted with electrical and plumbing fixtures.

In the following years, Kaufmann and Cullen built more than three dozen prefab and custom prefab homes in their own factory space, but today their homes are available exclusively through Studio 101 Designs of San Rafael, Calif. They offer three preconfigured home designs that can be built in varying sizes as well as custom modular home designs.

The cost of one of their modular homes fluctuates depending on the actual square footage. Kaufmann said the factory costs have been running between $175 per square foot (for a recent 2,500-square-foot house) to about $200 per square foot (for a recent 1,344-square-foot house). On top of this, there are shipping and setting costs associated with the modules that run around $8,000 per module or roughly $10-15 a square foot. If a crane is needed to set the modules, it costs about $8,000 a day.

The Contours model, with two bedrooms and one bath in 1,396 square feet, starts at $290,000 for the factory-built modules, which does not include construction fees, shipping, installation, foundation and other site features. When built with four bedrooms and three baths, in 2,650 square feet, the price goes up to $475,000.

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