Looking for energy-efficient alternatives to fireplaces

Fireplaces have great appeal in a house, but aren't energy-efficient. What are the alternatives?

When we discovered Sheep Dog Hollow last summer, the charming old home – which was yearning for some loving care – had two, rickety old chimneys. When we decided to buy and restore it in as green and economical a fashion as possible, I knew that we had to have a fireplace in it, or even two.

One of my favorite memories from my childhood was listening to my Virginia-bred mother telling stories about growing up on Lone Jack Farm, while she stood with her back to the fire, warming herself from the harsh cold in New England, where she’d come to raise a family. A fireplace was a must, if only for the warm memories it evokes.

But I also knew that fireplaces are not the most energy-efficient manner of heating a home. In fact, they’re quite the opposite. Conventionally designed fireplaces consume warm air from a room, the fire heats it up even more and sends it racing up the chimney. Then that air has to replaced with more air.

And where does it come from? Outside. And, as the 1940’s Frank Loesser classic Christmas song says, “Baby, it’s cold outside.”

A better explanation comes from the Masonry Advisory Council:

“In a cold environment, the air drawn into the firebox comes from the house and has already been heated to a comfortable temperature by the central heating system. As the air is expelled up the flue, it has to be replaced by more air. Where does this air come from? It must infiltrate the house from the outside, be heated up by the central heating, and then fuel the fire.”

Not exactly a “green” way to heat a home.

The other problem with fireplaces is that they have chimneys. Those chimneys are often built on the outside of a house. And when it’s cold outside, that masonry gets cold, too. In fact, it literally wicks cold, undermining the warming purpose of the fire in the first place. So, as beautiful as an old chimney is rising up on the side of a white clapboard home, it’s not very energy efficient.

Here’s more on conserving fire heat from the Masonry Advisory Council:

“The heat created by a fire can be used in several ways. One is to provide a masonry mass that absorbs, stores, and slowly re-radiates heat energy back into the room. This method provides a slow, low intensity heat source long after the fire is out. By the positioning fireplace wholly within the building envelope the thermal mass effect can be made more effective than if it was placed on the outside wall where heat would be lost.”

So we decided to tear down the existing outside chimneys, save the bricks, and build two more that would rise up inside the insulated envelope of the house.

But it turns out that there’s much more to building an energy-efficient fireplace than that.

The knowledge about how to build energy-efficient fireplaces has been around for centuries, literally, thanks to a Loyalist from Massachusetts who abruptly left the country in 1776 and then made a name for himself in Europe studying the nature of heat.

That name is Count Rumford, and in the next post I’ll write about why we decided to put at least one Rumford fireplace in Sheep Dog Hollow.

Editor’s note: Alexandra Marks blogs on Tuesdays and Thursdays about her green and budget-friendly restoration of a 1902 farmhouse in Connecticut.

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