Closed fireplaces sealed with glass-ceramic burn fuel more efficiently and radiate the heat throughout a room more evenly. For example, research by Schott found that fireplaces sealed with their ROBAX glass-ceramic used up to 43 percent less wood than a standard open wood-burning fireplace over the same time period, yet produce up to 26 percent more heat per kilogram of fuel than construction-grade open fireplaces.
Glass-ceramic can withstand temperatures up to 1400 °F, allowing a wood fire to burn hotter and more fully consume fuel. And because glass-ceramic radiates the heat throughout the room, it creates an even temperature that most fireplace radiators—which create convection heat—can’t achieve. In many cases, open fireplaces actually impair home heating by drawing excess warm air up through the chimney, leaving rooms cooler.
Closed, efficient fireplace systems also keep indoor air free of particles that might agitate those with allergies, and they also produce 70 percent less particle pollution than older, uncontrolled fireplaces.