Fireplaces and Health
You can spend a lot of time deciding on the look and feel of your new fireplace. You want it to go with the rest of the decor, to look attractive, maybe even artistic. But there's a more basic consideration you should take into account as well: you and your family's health.
We usually think of air pollution as something that occurs outside the home. But pollution can occur within your walls, and a poorly chosen hearth can add to that. The Environmental Protection Agency tells us that in-home pollutant levels can be anywhere from 2 to 10 times higher than what's outdoors. And since you probably spend more time indoors than out, this compounds the problem.
Homes built after 1980 feature tight construction. This makes sense for conserving energy. You don't want the warmth to escape in winter or the air conditioning in summer. But this presents new risks that need to be address. Tighter construction means less ventilation. Less fresh air comes into your home. And harmful air generated within has less opportunity to escape. Fumes can build up. Allergens can multiply. Moisture can collect in nooks and crannies and under carpet, leading to mildew and mold.
A fireplace should not add to this problem. And in fact, a well-vented fireplace can even be part of the solution. A fireplace should be designed to vent pollutants outside the home.
Unvented fireplaces add to the pollution in your home. The fire consumes indoor oxygen and exhausts fumes, soot, and odors. Right back into your home. You get to breathe the end results.
Unvented gas fireplaces can result in as much as a quart of water released into the air per hour of operation. The moisture can condense on window glass, making it difficult to see out. More problematically, the moisture can find its way under carpet, leading to mold and mildew.
For these reasons, many builders will refuse to install unvented fireplaces in homes.
A good, vented fireplace will do two things to combat these problems. It will take its air from the outside to fuel combustion. And it will vent the resulting fumes and pollutants back to the outside.
Direct vent fireplaces can expel virtually all of the moisture, carbon monoxide, and other unhealthy byproducts, leaving your indoor air just as clean as when you lit the fire. Newer, more sophisticated models can actually improve your indoor air quality. They can bring fresh air in while expelling the stale and unhealthy. A direct vent fireplace with a heat recovery ventilator will draw fresh air into your home, creating a more comfortable and healthier environment for you and your family. The same ventilator will act as a dehumidifier, actually removing some moisture from the indoor air, thus reducing the risk of mold and mildew.