Stay warm this winter: Backup power & space heating
Considerations for efficiency, economy and comfort
By Justin R. Wolf
ANOTHER WINTER approaches, as it’s wont to do. Even with a warming climate and the 2023-24 winter season being one of the mildest on record for the Pine Tree State, the possibility of getting a string of subzero nights, multiple Nor’easters, and several multi-day power outages is increasing. Whether you’re inland or coastal, in the mountains or in the County, needs will vary but one thing is a constant: you may want some backup.
Backup power and heating are critical when considering outages, which are inevitable regardless of where in Maine you call home. And depending on the design of your home and reach of your heating system, space heating may also be important to ensure all areas of your home stay comfortable when the mercury drops.
Backing up power
“This comes up on pretty much all my projects,” says Michael Maines, a sustainability specialist and designer of highperformance homes. In the event of multi-day outages in the winter, “if the house is on city water and it just needs backup heat, then a wood stove is a good option. And obviously go with an EPA-approved one that limits emissions.” If the home is equipped with solar power, Maines cites solar battery storage as a suitable backup option but admits that a $10,000 price tag for a Tesla Powerwall, for instance, might be impractical because such systems are typically only good for 24 hours of reserves.
His top recommendation is a generator. “Most people prefer standbys that come on automatically.” While whole house generators may be preferable, that level of insurance also requires a lot of fuel to power the home. An alternative is to plug it into specific circuits. “So, you may be able to run heat pumps and your refrigerator but not an electric oven or something else that draws a lot of power. And if you’re on a well, having a generator is helpful because otherwise you don’t get water.”
In Maines’ own home in Palermo, he keeps a gas-powered portable generator, which he estimates cost him $1,500, plus another $100 to install a manual lock-out switch, allowing him to conserve fuel and direct energy to specific points. “It works just fine. It’s just more effort.” It also saved him more than $13,000 that would have gone toward installing and hooking up a standby generator and reserve fuel tank on his property.
For high-performance homes with continuous insulation, Randy Rand, co-owner of Orono-based r.haus and the training director for passivhausMAINE, cautions against including even a small wood stove for backup, since it will quickly overheat the space. Like Maines, Rand keeps a portable generator handy. Provided the home is air sealed and well insulated, he recommends nothing more than a small electric space heater
Space heating
Surviving the cold is always top of mind for Mainers. The cold climate heat pumps recommended by Efficiency Maine offer superior efficiency relative to combustion furnaces, even when outside temperatures drop as low as -22°F. However, depending on how well insulated and airtight your home is, when the temps dip well below zero for multiple days—or if you have an area of your home where your heat pumps don’t reach—you may want a source of backup heat.
One option to supplement your heat pump is a gas stove. However, if you are interested in reducing or eliminating fossil fuel use altogether, a woodstove or pellet stove might fit the bill. Either option offers tremendous ambient heat, efficiency, and aesthetic appeal. Though, keep in mind that if the power goes out, pellet stoves require electricity to operate.
At the other end of the spectrum are all things electric. Small plug-in resistance space heaters (freestanding or wallmounted), positive temperature coefficient (PTC) ceramic space heaters, grounded baseboard electric heaters, or less common electric furnaces are all low-maintenance and efficient options, especially for heating isolated cold spots in the home. Average costs for these devices range from as little as $25 up to $2,000, in the order mentioned. They are also the least carbon-intensive heating option, owing to the high makeup of renewable energy in Maine’s electricity supply.
Relying on your home
Another backup option is the home itself. A home’s airtightness and thermal envelope are key, Rand says. High-performance homes, whether built to Passive House standards or similar, are made to ensure surface temperatures remain constant throughout the home, there is adequate— though not excessive—solar gain, very little to no thermal bridging, and continuous insulation. Rand notes that in power outage situations, these homes “give you more time to still be comfortable and not be in an emergency.”
Contemporary homes built to such standards are modestly sized and centralized heat pumps are often the sole heating source. And should an otherwise well-insulated home have inefficient windows with low R-value (heat resistance) and U-value (heat transfer), the use of thermal curtains or window inserts can be an effective stopgap.
When it comes to backing up your home’s heat or power, options abound. Having backup, while not necessarily essential, will give any Maine homeowner peace of mind. But that’s only the beginning. The rest is getting to know your home’s strengths and weaknesses and deciding what type of equipment—appliances or otherwise—will deliver optimal levels of energy efficiency, cost-effectiveness, and personal comfort.
This article appeared in the Fall 2024 edition of Green & Healthy Maine HOMES. Subscribe today!
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