Question: I am about to build a house. I am wondering if gas log fire places really heat a room? How efficient are they at putting heat into the room? I do not want an unvented one. Please let me know the pros and cons, and if wood would be better. Answer: An open gas log fireplace will not heat the room well. But a sealed unit, commonly called "Direct Vent" can produce quite a bit of heat. The better units even can operate from a thermostat, allowing control of the heat. These units have high efficiencies, in the area of 60% to 80%. The choice of wood or gas is more of a lifestyle choice..do you enjoy cutting and stacking wood? The smell of a woodfire? Gas cannot duplicate these things...but it CAN heat your room and home.