by Lora Whelan, published in the Quoddy Tides, September 26, 2014
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 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 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-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 foe 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.