Berkeley zero net energy cottage deserves study

Karen Chapple's just-built second home looks exactly like what it is: a cottage that packs 450 square feet of living space into a traditional shell with a pitched roof, warm wooden walls and a shaded front porch.

Old news - except that it sits tucked behind a century-old bungalow on a quiet Berkeley block with neighbors close on either side, stealth infill that in its own discreet way deserves study by every city where the need for housing outstrips the supply of obvious land.

The cottage was erected this fall for $98,000, a budget extended at the end to include such niceties as granite counters in the lilliputian kitchen alcove. Construction took three months. Tenants move in this week.

This isn't the only such unit to pop up in the Bay Area during the past decade, though it might be the only one that can lay claim to "zero net energy status." The project includes eight solar panels, and they provide enough power to take care of all the cottage's needs.

Still, the cottage definitely is the exception to the rule - a fact that owner Karen Chapple would like to change.

"It's not a new idea, but there has tended to be more talk than action," says Chapple, an associate professor of city and regional planning at UC Berkeley's College of Environmental Design. "We haven't done the hard work here to understand the barriers that keep it from happening."

Planning theorists such as Peter Calthorpe for decades have touted the virtues of so-called "in-law units." A 2002 regional growth study by the Association of Bay Area Governments estimated that such units could increase the supply of housing in older transit-friendly neighborhoods by 5 percent.

But none of this as yet has translated to real momentum - even though it seems like an obvious way to create relatively affordable housing for people looking for alternative ways to live, whether it's a parent who needs to downsize or a single person with a job nearby.

"It's something that people want in the abstract," said John McIlwain, a senior research fellow at the Urban Land Institute in Washington, D.C. "The need is there, and a number of communities are starting to talk about it, but there's often resistance at the neighborhood level."

Chapple herself has a $60,000 grant from the UC Transportation Center to study the potential for adding single units to the backyards within a half-mile of five East Bay BART stations. It won't be completed until next summer, but her initial take is that there's room conceivably for 4,000 such units in Berkeley, many of them replacing old garage structures now used for storage.

That's the equivalent of 11 One Rincon towers, and next-door neighbors would be the only folks who know they are there.

The hurdles? Parking or perceived lack thereof. Neighbors wondering who might move in. The fact that a building project is a lot of work, and many of us don't have a lot of time.

In her case, Chapple's "very own local stimulus package" was fueled not so much by ideology as need; by refinancing her existing home, the single parent could add a cottage and thus a paying tenant, helping with the monthly bills.

She worked with engineering students to devise ways to keep the cottage off the energy grid; by increasing the width of the wall boards from four to six inches, for instance, there'd be room to install more airtight insulation. On the design and approvals she worked with New Avenue Homes - a start-up by a Berkeley MBA to build "affordable green homes" - and architect Mark Creedon. The builder was Thomas Goetze.

Would I personally want to live in Chapple's rustic-looking backyard cottage? Not while I'm 6-plus feet tall and the pitched sleeping loft peaks at 5 feet 3 inches. But it's a well-done space, inviting as well as concise, homey in all the right ways.

More important, it makes the point that there are ways to add housing to Bay Area communities short of tall towers, or squat boxes along busy thoroughfares.

Our best older neighborhoods are threaded with residential spaces of all types, often in dimensions and locations you don't expect. Modest as it is, Chapple's cozy retreat is a 21st century reminder that one size needn't fit all.

Place appears on Tuesdays. E-mail John King at jking@sfchronicle.com.

This article appeared on page E - 1 of the San Francisco Chronicle