MMA Building Project Designed for Energy Efficiency
(from Maine Townsman, November 2008)
By Doug Rooks, Freelance Writer
MMA’s new building project, a separate 9,800 square foot structure behind the current headquarters — is being designed as a model for energy efficiency. It’s expected to include everything from high insulation values and better temperature controls to one of the area’s first geothermal heating and cooling systems.
The latter feature is still tentative, pending results of test bores in December on the site, down the slope from the Augusta Civic Center.
But MMA is quite serious about the potential for more efficient operations, according to Christina St. Pierre, director of MIS & Administration, who’s coordinating the project. Construction will conform with LEED guidelines (See “LEED Certification,” Townsman, August/September), though without formal certification of the results.
And while geothermal systems are relatively unfamiliar in Maine, they’ve been around awhile, she said, dating back to an installation at the Black Point Inn in Scarborough over 20 years ago.
St. Pierre said that among the energy-efficient LEED elements will be water use reduction, use of regional material, incorporation of daylight and views in most offices, and an overhaul of the heating-ventilation controls in the existing MMA headquarters.
“There have been a lot of advances since the existing building was finished” in 1994, St. Pierre said. “We wanted to do as much as we could to bring everything up to today’s standards.”
Dave Shanks of Foreside Architects, a designer for the project, said that it makes sense to use the existing HVAC system in the current building while retrofitting it with advanced controls. “It’s like a car that’s five years old, and paid for. There’s a lot of use left in it, so you don’t buy a new one right away.”
Shanks said the siting of the new building, with the entrance on the south side, makes good energy sense as well. “You like to have openings where the building is warmest, and where it will also shed the snow load fastest,” he said.
The existing building is heated with propane, which has been more stable in price than fuel oil and still makes sense for a building of this size, Shanks said.
Retrofitting the existing building to take advantage of the proposed geothermal system probably wouldn’t make sense, according to Douglas Martin, an engineer with W.H. Demmons, who’s the Portland firm’s team leader on geothermal projects. “If you’re starting from scratch, or completely replacing the HVAC system in a building, it could make sense, but not here.”
On the other hand, Martin has little doubt that geothermal will work at the MMA site. “About the only places we’ve found in Maine that aren’t suitable are along the coast,” he said. And that isn’t because of any inadequacy of the geothermal wells themselves, but due to potential effects on other wells used for drinking water.
Geothermal wells are typically deeper than other drilled wells – usually 500 feet or more, against as little as 50-foot depths for drinking water – and such wells have the potential to bring seawater into the water column. Inland, he said, there’s a much smaller chance of interference, though experience in the business is helpful; W.H. Demmons has been at it since 1992.
The basic principle of geothermal systems is simple – drill down until you find water at the same temperature as the annual ambient air temperature, In Augusta, that’s about 50 degrees F. By drawing up water that’s warmer than the air and using a heat exchanger, the building can be heated; and, in summer, the same differential cools the building.
“We recommend that systems be installed both to heat and cool,” Martin said. “That way it’s a closed loop, with no discharge outside the system.” The exchange of water between the surface and subsurface also creates what Martin calls a “flywheel effect,” where the seasonal temperature changes are anticipated and amplified by the system.
Since 2001, W.H. Demmons has installed geothermal systems in a number of new public and institutional buildings, including classroom buildings at Maine Central Institute in Pittsfield, Merriconeag Waldorf School in Freeport, University of Southern Maine and an alumni center at Colby College. Other projects include the U.S. Customs House in Portland, the new York County Courthouse, and the Saco & Biddeford Saving Institute. Building sizes have ranged from the 4,000 square foot bank building to the 45,000 square foot courthouse. MMA’s project will total just under 10,000 square feet.
Martin said there’s been a lot of interest in geothermal since energy prices began soaring a year ago. “We’ve got at least a dozen projects in some stage of design or construction,” he said — up considerably from recent years.
MMA’s interest was definitely piqued when it became clear that payback for the increased costs of geothermal in the addition was just five or six years, St. Pierre said. “That made it a whole lot more practical from our point of view,” she said.
The pumps used in the geothermal system have about the same lifespan as those used in conventional heating and water systems, about 15 years, Martin said. “ In many respects it ’ s just like having a conventional kind of heating system except there are no fuel costs. ” And like any drilled well, as long as the geological layers don ’ t shift and the core remains stable, it should last indefinitely, paying dividends far into the future, he said.