Thursday, December 12, 2013
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Bruce Merryman, project manager for Evergreen Home Performance, points to an open area around a chimney to be insulated as apartments in South Portland are weatherized last week.
Photos by John Patriquin/Staff Photographer
Michael Bunker, left, and Eddie Elwell of Evergreen Home Performance wrap insulation around heating ducts while weatherizing South Portland apartments. The most cost-effective way to spend $600 in most Maine homes is on weatherization and air-sealing.
John Patriquin/Staff Photographer
"It doesn't necessarily make sense to just move burners around, if houses are like Swiss cheese and leaking like a sieve," he said.
AIR SEALING SAVINGS TOP $280 A YEAR
The benefits of air sealing are well documented but not widely appreciated. As it happens, Efficiency Maine currently is offering $600 rebates for air sealing, using money from a federal grant. The program has sealed 2,331 homes since last fall.
The work has cut air leakage by an average of 16 percent, which translates into saving of 75 gallons a year in a typical home. At today's oil prices, that adds up to more than $280 a year.
Achieving those savings requires attention to detail.
In South Portland last week, crews from Evergreen Home Performance were air-sealing 24 apartments at Mill Company Gardens. Built in the 1930s for the Coast Guard, the units have had some basic energy improvements over the years. But tests run on the buildings show missed opportunities.
In the basement of one unit, Bruce Merryman, the project manager, pointed to the gap between the chimney and framing, where someone had stuffed fiberglass insulation. It looks helpful, but air moves freely through fiberglass, doing little to blunt the "stack effect" that draws cold air up from the cellar into the house.
Merryman's crew blocked the gap with fireproof flashing, and sprayed foam where pipe and wires run through the floor. They also sealed seams in the aluminum heating ducts from the furnace, and wrapped them in foil-faced fiberglass blankets. That will slow heat loss from the warm ducts to the cool cellar.
"We're insulating the hottest air that has the most heat loss in the system," he said.
REDUCING DEMAND FOR ENERGY
To pick the most cost-effective measures, Evergreen performed a full energy audit on the apartments. Audits typically cost $300 to $600. Included in the audit is a blower-door test, which depressurizes the house to reveal air leaks. It's still undecided whether the $600 rebate envisioned by LePage would require homes to have full audits or blower-door tests prior to air-sealing work.
An added benefit of air-sealing is reduced energy demand, allowing for a smaller heating system. Tighter homes may be able to rely largely on supplemental heaters, such as wood and pellet stoves, or the new generation of high-efficiency, air-source electric heat pumps for cold climates.
For example, Bangor Hydro-Electric and Maine Public Service Co. are running a heat pump pilot program this winter, offering a $600 rebate to early participants. The units cost more than $3,000, but they are expected to reduce the need for oil heat enough to pay for the investment in three to five years.
"I'm hoping that, more and more, people look at the building envelope," said Lee Landry, co-owner of ReVision Heat in Portland.
ReVision sells a range of alternative options, from the new electric heat pumps to boilers that can warm large homes with wood pellets. It also offers customers a spreadsheet analysis, so they can weigh costs and financing options.
Converting an existing oil burner to natural gas costs $4,500, and saves $1,864 a year, at today's energy prices. That's a simple payback of 2.4 years.
A burner conversion isn't as efficient as a new gas boiler, though. But the upfront cost after a federal tax rebate -- $12,337 -- would drag out the payback for a new gas boiler to almost six years.
A wood-pellet boiler also requires a major investment -- $16,000, in ReVision's example. That would lead to a nine-year payback at today's energy prices.
A different cost comparison was made by Efficiency Maine (see chart on B1), using 400 recently completed projects. The calculations, done for the Maine Sunday Telegram, include the LePage administration's proposed $600 rebate. They show paybacks ranging from nearly six years for replacing an oil boiler with a high-efficiency gas unit, to two years for insulating an attic or basement, and seven months for basic air sealing.
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