Clara Kim and her husband are nearly finished planning their new custom home. Only a few details remain before they can seek construction bids. But one of the remaining loose ends has major energy implications.
“We are planning to have a wood fireplace on the ground floor, within the building envelope,” Clara writes in a Q&A post at Green Building Advisor. “When it is burning, it will likely [be] burned with any glass doors on the fireplace open, for aesthetic reasons. It is only going to be used as a heat source as an occasional backup.”
Her husband refuses to consider a more efficient gas or wood stove, nor does he take kindly to her suggestion the fireplace be moved to the patio outside. No, the fireplace is going to be inside and it will be used without glass doors that would minimize heat loss.
A generation ago, that might not have raised an eyebrow. What could be more natural than a fire on an open hearth? These days, however, the energy inefficiencies of fireplaces have turned them into the equivalents of chamber pots and single-pane windows.
Kim is still holding out hope that some means can be found to minimize the energy shortcomings of her husband’s plans. Or is that an uphill fight? That’s the topic for this Q&A Spotlight.
Sorry, they’re never a good idea
Dana Dorsett gets right to the point, summing up what looks like a common point of view: “An open-hearth fireplace (with or without glass doors) is an inefficient, extremely polluting way to burn wood that has no place in a ‘green’ house,” Dorsett writes. “They are even illegal to use in some locations due to the particulate emissions problem.”
Darryl in Winnipeg adds that “burning anything with the doors open is not a good idea at all.” His EPA-certified zero-clearance stove/fireplace is in use all winter long. “With the doors closed and the fire shining through the glass, I get all the aesthetic benefits I need,” he says.
“In most homes, operating a wood fireplace without glass doors results in a net loss of heat,” says GBA senior editor Martin Holladay. “A fireplace can’t heat a home. If you are operating a wood fireplace, the best you can hope for is to warm your hands as your house gets progressively colder.”
“I think her husband’s silliness stems from a lack of physical intuition and this kind of behavior must be disturbing to those people living around people like that,” says Eric Habegger. “Perhaps people of all skill levels should be encouraged at some point in there lives to get their hands dirty and understand what actually goes into the world we live in. Maybe a suggestion to the husband that it would be ‘romantic’ to get a horse and buggy would be in order.”
There’s also the possibility, Beth Turner suggests, that a fireplace could create insurance issues. She adds: “As we become more concerned about emissions and air quality, and considering an open fireplace is one of the worst offenders in that regard, it seems like one might want to proceed cautiously. It’s always a good idea to think about where we might be headed in the future and plan accordingly.”
Designs and detailing may help conserve heat
There may be an exception to the rule, counters Ven Sonata, who recalls reading of a physics professor who insisted on an open fireplace in her country home and had “researched the hell” out of the subject. “She found a custom design that she claimed had all the efficiency of a modern wood stove,” Sonata writes. “She liked the reality of crackling mesquite.”
Although he’s unable to provide a specific reference for the professor’s fireplace, Sonata refers Kim to a Canadian company called Renaissance Fireplaces, which makes an updated Rumford design that is “truly impressive.” The fireplaces, he says, promise 50% efficiency with the door open, “not great compared to some wood stoves at over 80 percent, but still if not used often and only for the aesthetics not a problem.”
Others offer suggestions on how energy losses from a fireplace can be minimized: a chimney “balloon” that seals off the flue when the fireplace is not in use, shallow Rumford designs that produce more heat than conventional fire boxes, doors that can seal the fireplace and prevent heat losses, an airtight chimney cap.
Avoid exterior chimneys, says Keith Gustafson, and install an external air supply. “The worst thing about fireplaces is that they draw air from other rooms and cool them,” he says, adding: “Close the damn doors. Are ya just silly? Really?”
If it weren’t clear already, Malcolm Taylor tells Kim she’s chosen a subject that is guaranteed to irritate some readers.
“You would have gotten a similar reaction to innocently suggesting using windows for ventilation, and will find similar reactions to electric bikes on cycling forums, or to mixed-breed dogs on pure-bred sites.” Taylor says.
Finding refuge from ‘butt-in-skis’
Are fireplaces really so awful from an energy and air quality point of view they should be banned in new construction? A GBA reader named SE thinks so, but to Alex House, the argument smacks of intolerance and government meddling.
“The expansive reach of building codes is already intolerable, what with things like energy mandates being shoved into the code and which have nothing to do with structural or fire issues,” House writes. “Now you want to outlaw fireplaces because they rub you the wrong way.
“If not one’s home, where can one go to live life as he pleases without a bunch of bureaucrats telling everyone how they must live?” House continues. “Where can one find sanctuary from butt-in-skis?”
“Nowhere within civil society,” replies Nathaniel G. “That’s not the kind of place we live in anywhere. Those of us who chafe at it best get used to it or become a heck of a lot more active in fighting it.”
Or, as Holladay suggests, get away from bureaucrats by settling in a rural area where no building codes apply. “Most building codes don’t outlaw fireplaces,” Holladay notes. “As long as the fireplace complies with your local building code, you are free to install one. If you want to install an unusual fireplace that doesn’t meet code, you’ll have to buy some rural land.”
He also notes, “The problem with homes that include idiosyncratic features that happen to be bad energy details is that these homes are eventually sold to unwitting buyers who don’t realize that the former owner liked to have campfires in the living room — ‘damn the energy penalty,'” Holladay says. “It’s hard to balance the rights of people who want to be eccentric with the rights of those who invest hundreds of thousands of dollars in a home to keep their family warm during the winter.
“For now, our country has decided to protect unwitting home buyers in suburban and urban areas, and to let the campfire-in-the-living-room crowd build their homes in rural areas.”
But House isn’t buying it. “Energy purists take the position that fireplaces are energy inefficient and the extremists want them banned,” he says. “I can’t begin to tell you how much this rubs me the wrong way — nannies imposing their standards on others. Martin at least grants people some liberty to do with their home what they please, if allowed by code.
“Energy efficiency as a principle obviously appeals to the writers and readers of this site, but just because we find it appealing doesn’t grant this principle any added legitimacy such that it should be shoved onto other people who have different values or priorities. If someone wants a fireplace, then terrific for them — they get to enjoy the benefits and suffer the costs. Not my business or anyone else’s.”
Our expert’s opinion
GBA technical director Peter Yost had this to add:
There is no question regarding the building science here. For every cubic foot of warm interior air headed up and out that fireplace (more than 500 cubic feet per minute for a blazing fire), a cubic foot of cold outside air is being pulled into the building. The only folks warmed by the fire are those within radiant reach; everyone else will be reaching for their sweaters or the thermostat.
And then when the fireplace is not in use, there is the loss of warm interior leaking past the fireplace damper (if indeed it gets closed after the fire is out…).
We let folks do “non-building science” or “anti-building science” stuff all the time: 1500-cfm range hoods, unvented gas fireplaces, clothes dryers vented to the indoors, gas cooktops, attached garages… (Now these last two are bound to really rankle.)
To me, if you want an open fire, make it a truly open fire — outside your home. If that won’t fly, and the owners understand the true costs of the interior open fireplace, so be it.
Whether public policy as expressed by the building codes represents the right balance of individual freedom and common cause probably won’t be settled by a GBA blog. But kudos to our online community for a strong and balanced discussion of the issue.