Three new buildings in Washington County are providing examples of energy efficiencies and heating systems that use everything from cordwood to geothermal heat to solar gain. Two are big, multi‑use spaces with large budgets and one is a 1,300-square-foot residence built with self‑sufficiency in mind.
     Architect Bruce Stahnke, involved with the Cobscook Community Learning Center's Heartwood Lodge project, says, "Anyone who has a public building into perpetuity has an incentive to look at alternative systems, and there's payback, for sure." Karl and Jane North, who built the modest and comfortable passive solar home in Robbinston, believe that modeling energy efficient buildings "should be done now instead of later" because of the increasing costs of fossil fuel‑related energy sources.
       The Heartwood Lodge project at the CCLC in Trescott is the largest, with a $2.8 million budget, a new dormitory completed, a new classroom addition in the works, and a heating system designed as a district system that will eventually serve all the buildings on the campus, says Stahnke. The dorm alone is 6,284 square feet, a size that would give many a homeowner in the county pause at the thought of heating such a space. The classroom addition to an existing building will add 3,345 square feet to the heating system load. But like the new 3,024-square-foot administrative building at the Moosehorn National Wildlife Refuge and the 1,300-square-foot passive solar residence in Robbinston built by the Norths, the Heartwood Lodge has been built to keep energy use to a minimum.

Insulation, airtight structure equal energy savings
     The first thing anyone wants to know about an energy efficient building is how much annual operating cost is associated with its energy systems. While all three are new with a limited history, the North house has two winters under its belt, with each season using on average a little more than two cords of wood to augment the passive solar system. In 2013 the Moosehorn was still using the three old staff buildings with about 6,000 square feet, costing $9,100 for heating oil and electricity. Like the North home, the new Moosehorn building utilizes solar gain on its south side, but the bulk of its heating system comes in the form of two geothermal wells that are used for a forced air system that uses electricity to run the pumps and augment the water temperature. Over the past winter the building was running with an average monthly cost of $220 for a total annual cost of $2,650.
     "There's a two‑thirds savings in energy expenditure," says Assistant Refuge Manager Steve Agius of the $1.5 million project, which includes everything in the building but the computers.
     The Heartwood district heating system of two cordwood gasification furnaces surrounded by 2,000-gallon insulated water tanks each is expected to use between 30 and 40 cords of wood annually to supply the entire campus with either radiant or baseboard heat. In addition the dormitory will use a solar hot-water heating system to keep the showers running smoothly. For their potable hot-water needs, the Norths use a solar hot-water collector during the warmer months and switch to a wood stove water heater during the winter months. The Moosehorn also utilizes a solar hot-water collector for its year‑round potable water needs, but because the administration building has no bathing facilities, the load is minimal.
     Key to the performance of all three projects is the insulation and ventilation. The three very different buildings rely on a significant amount of insulation, including 4" of rigid foam board around the foundation walls and under slabs, different types of wall and ceiling insulation but all with high R‑values. Karl North notes that his walls are R‑40 and the ceiling R‑60. Assistant Manager Steve Agius at the Moosehorn lists their new building as R‑36 in the walls and R‑60 in the ceiling.
     Before the drywall went up at Heartwood, architect Stahnke had a blower test conducted, a pressurized testing system used with an infrared heat gun that shows where air leaks exist, allowing warm interior air to leave the building and waste energy. "It performed really well," he says. Anything that needed to be fixed could be done that much more easily since the interior finish work had not yet been put in place, a handy tip for any homeowner to tuck in their tool kit. North did the same thing, and was able to correct some mistakes that took place when the local contractor discovered some issues with the insulation and vapor barrier installed by a contractor from another county.

Local contractors the key to success
     Local contractors were responsible for the success of each project, Stahnke, Agius and North say. All three men note the level of workmanship and care that local contractors and builders took with implementing complex buildings utilizing insulation layers, vapor and air barriers and critically important ventilation systems. Stahnke says, "It's hard to overemphasize how much workmanship affects the final outcome. If the contractor is not convinced in their heart that airtight is going to work, it won't get done. That message gets conveyed down the line." Agius comments that using local contractors was very deliberate. Locally sourced materials were used in all three projects whenever possible.
     The Norths couldn't agree more about the importance of having a contractor who is enthusiastic about being responsible for an unfamiliar style of construction. While the design behind their passive solar system has been around for a while, it is probably the least well known. The passive solar design uses a ducted system put in place within the slab. A hollow column rises to the peak of the home's interior ceiling where rising warm air is collected, blown down and circulated through the slab's channels. The slab's mass, collecting heat from the expansive array of south‑facing windows, radiates warmth into the channels and is blown by the fan back into the open‑concept house through evenly spaced ducts.
     The passive solar design is simple and elegant. The wood stove in the kitchen and the Rumford fireplace on the other side of the massive chimney add the extra oomph of warmth on the coldest days. However, Karl North notes that during the winter that it was constructed and no supplemental heat was used the contractor recorded that the interior temperature never dropped below 45 degrees. During the past two winters with the wood stove and fireplace closed down at 8 p.m., the Norths found that temperatures stayed quite comfortable with a drop from 72 to 68 degrees during the night. Helping to retain the heat are insulated shutters and carefully fitted insulated shades that hug the windows. The Moosehorn building also uses energy saving shades in its conference space.
     All three projects carefully manage the energy that is used within their walls by having zones for individualized temperature control. The Norths' house uses the simplest approach, with heating vents that can be closed, doors that can be opened or closed to an attached and well‑insulated greenhouse and to the north‑side bedroom, bathroom and office, and a large utility room on the northeast side of the house that receives heat through the slab but has very little southern exposure glass and a door between it and the rest of the house to keep out wood stove heat. Each bedroom at the Heartwood Lodge has its own temperature control. The Moosehorn building is separated into five zones more along the lines of the Norths' house: two large zones oriented toward the north and south of the building because of solar gain on the south side, plus three zones for each enclosed entryway.
     If they could do it again, the Norths, with this being the third passive solar home they've worked on over the course of their lives together, would orient it with less of a mind to the stunning view and more to maximize solar gain. As it is, they have an opportunity to try another solar design, a solar hot-air collector on their west‑facing wall. Solar hot-air collectors are a technology considered by many alternative energy experts as one of the most cost-effective solar collection devices for Mainers. North has been talking with his contractor about building one and is looking forward to exploring the idea further.
     Despite the large size and budgets of the Moosehorn and Heartwood projects, they have elements similar to the Robbinston project that can be utilized by homeowners. "I would say that the construction methods are not completely alien for residences," says Stahnke. "Everything we did has a residential version. I would love for people to get some sense of what you can do with wood frame construction, airtight with good ventilation, and how much you can save" on energy costs. He adds, "Even with single‑family houses you can do things to make an expensive heating system go away. You put it in your walls instead." Like the Norths, Stahnke believes that the future lies with highly efficient buildings and locally sourced resources with lessons to be learned from cordwood, the sun and the ambient temperature buried deep in the earth.