BOOTHBAY HARBOR – Thirty years ago, Michael Mayhew bought a 1930s summer cottage on a hill overlooking the harbor here. He knew it had a good southern exposure — the dry, brittle shingles fell apart when he tried to paint them.

“I said, ‘Yes, this was the right place,’” Mayhew recalls.

Since then, he has gradually expanded the cottage into a four-bedroom, 2,900-square-foot local landmark that integrates an array of renewable energy and green building features, set against a background of do-it-yourself funkiness.

High-tech solar electric panels on the roof contrast with recycled motel windows in the kitchen. The ceiling of a new tower/dormer bedroom has sprayed urethane insulation and a reflective barrier to achieve an extreme R-factor of 80, while the framing is supported by a driftwood log scavenged from the ocean.

It all works. Mayhew gets about three-quarters of his heat from the sun, and enjoys $10 monthly electricity bills, on average. But he’s still not satisfied.

“There are plenty of places that could use more insulation,” he said.

Few Mainers approach home energy matters with Mayhew’s passion. But as a potentially expensive heating season begins, there are helpful lessons to be gleaned from his experience.

Those lessons are on display today at Mayhew’s house and 57 other buildings in Maine that are open to the public for the 15th annual Green Building Open House tour.

The tour is organized by the Massachusetts-based Northeast Sustainable Energy Association. The goal is to let residents get a firsthand look at energy efficiency and renewable energy applications in their communities. Last year, more than 10,000 people toured 500 buildings from Maine to Pennsylvania.

Residential solar installations have been a focus of the tour in the past. The Maine buildings this year include two dozen with solar electric or hot water panels installed by ReVision Energy of Portland, one of the event’s organizers.

This year, the association also wants to showcase a variety of strategies, including so-called deep energy retrofits, which feature major insulation and efficiency upgrades to existing buildings. Four of those are on the Maine tour this year, including a house in Portland, designed by Kaplan Thompson Architects, that’s heated for $350 a year.

Also new on the tour this year are commercial buildings, such as Falmouth Elementary School, which has geothermal cooling, a wood-chip boiler and a “green” roof covered with native plants.

“Solar is fabulous, but there are other things people can do,” said Michelle Rose, the association’s program manager of the tours.

The continued downturn in the housing market has more residents looking to upgrade existing homes, Rose said, so it makes sense to highlight retrofit ideas.

Mayhew’s house is a study in add-on and upgrade strategies. And it underscores the fact that green building can be done on a budget. Mayhew estimates he has spent $65,000 over the years on renovations, aided by small bank loans and his own sweat equity.

One of his first improvements was an attached, 24-foot-long greenhouse that brings sunshine and heat into the kitchen area. A brick-walled pool, filled with 1,000 gallons of water, stores warmth and moderates temperature swings. Surrounded by plants, it is an oasis in winter.

Two solar panels on the roof heat water. The output pipe was measuring 165 degrees on a clear morning this week. Six solar-electric panels, a hybrid system that uses homemade reflectors to concentrate the sun’s rays, and lots of south-facing glass, also help Mayhew make the most of his home’s exposure.

A wood-burning stove, a high-efficiency propane boiler, a radiant floor loop and two kerosene heaters round out the heating equipment.

Tinkering comes naturally to Mayhew, an engineer who heads an alternative-energy consulting firm, Heliotropic Technologies. But as much as he likes harnessing the sun’s energy to make electricity, Mayhew believes the cost benefits of big solar systems are overstated for most homeowners.

“Insulation is the most important thing,” he said. “You want to be shrinking your heating load. And I’ve got tons more to do.”

Although Mayhew’s house has a bedroom roof with twice the insulating value of most homes, other parts of the structure still need work. Out back, he pointed to a 2-by-4-stud wall where he’s adding 2-inch-thick sheets of foam board.

Mayhew’s four children have grown, so every room in the sprawling home isn’t occupied these days. But he’s still chipping away at energy improvements, with a long-term goal of making the house efficient enough that it generates more power over the course of a year than it consumes — an achievement called net zero.

“Doing more with less, that’s what it’s about,” he said.

Staff Writer Tux Turkel can be contacted at 791-6462 or at:

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