Our only heat in Creuse, other than a tiny bathroom electric heater, is wood. And here in California, we have a quite efficient (Vermont Castings! USA! USA!) fireplace. It does get chilly here, but nothing like has been felt in central France recently. Where we are, out on the coast, there are no controls on when we can burn wood, but inland, when the air is still, there are days when wood fires are forbidden. Modern fireplaces are generally relatively non-polluting, due to catalyic or other smoke scrubbers.