The building is a 2000 sq.ft. two-story private residence and 500 sq.ft guest house in Williamstown, MA. with the goal of being a “zero net energy” home—this means generating on site as much total energy as is consumed over the course of a year.

One of the Owners teaches Environmental Policy, and was the lead author on the Intergovernmental Panel on Global Climate Change’s 2003 report for the UN, therefore the goal was to avoid fossil fuels completely and instead to rely on photovoltaically generated electricity and on ground source heat pumps for both space heating and hot water (there is no air conditioning). This is a significant design requirement—it drives a radical review of investment, particularly so far as the building envelope is concerned. More dollars than normal are spent on reducing demand—because the Owner is also buying the supply infrastructure.

So the question for construction dollars is… Where do I get my best return… by adding more PV… or by improving the thermal performance of the windows, the walls, the roof… by reducing infiltration, by recovering more heat from the exhaust stream… or the waste shower water… or by reducing the load on the well pump…or the heater circulating pumps…lowering the wattage of lights; reducing their number; controlling them more effectively…? and so on. [After that comes a similar list of behavioral patterns that confront the Owners once they move in.]

Along with the important subtleties of siting for views; protection from winds; solar optimization… and designing an attractive elegant building—we are thinking about how to live with an energy budget.

The Owners have friends from far and wide, and an important requirement was to provide for guests- who might stay a while. They also want the occasional ambiance of a wood fire (after all they are in a rural location with trees all around). Considering these together—it was decided to break the building into two. A separate guest “wing” would offer the privacy and independence that would elevate the experience of the guests—encourage friends to come all the way to Williamstown, MA—and it would allow that part of the building to be run at a lower temperature in winter, thus saving energy. By putting a wood stove in the guest house, the place could be rapidly brought up to temperature without relying on the PV system. It also confined any adverse particulate to the less intensively used portion of the house.

The house, its Owners, and Architect are also the subjects of a video presentation, now in production, being produced by Zachary Zevitas, an instructor at Harvard. Click these links to see clips:

Zero Energy Home does not externalize the cost of energy (time: 02:44).

Zero Energy is a lifestyle choice (time: 03:24).

On-site discussion of Larsen Truss with Architect Bruce Coldham (time: 03:38)
Thanks to Zach for posting these clips.

A commissioning visit by the team can help ensure that all parts are working as designed, but the proof will be in the pudding. We plan to keep track of the building's performance for at least a year after the Owners move in. Stay tuned.

Structual Engineer: Ryan Hellwig, P.E. (Northampton, MA)
Mechanical Engineer: Petersen Engineering
Landscape Architect / Site Design: Walter Cudnohufsky Associates
Photovoltaics: Chris Killfoyle, Berkshire PhotoVoltaic Services
General Contractor: Haskins Construction (Williamstown, MA)

The Moomaw Residence is featured this year on NESEA's Green Building Open House, part of the nation-wide ASES National Solar House Tour on Saturday, October 7, 2007.