All gas fireplaces using a self generating millivolt system and gas pilot valve do not need any electricity to operate. Only accessories such as blowers and some hand held remotes rely on house current for power. This is easily calculated provided that you have the local price of the fuel to be used. The BTU of the fireplace is divided by the BTU value of the fuel to determine the amount of fuel consumed per hour. Therefore the cost of operating a 30,000 BTU Natural Gas Fireplace for one hour is 10.5 cents.
Radiant heat is transmitted from a heat source via rays just like rays of sunlight.
These rays pass through the air without heating it since only solid objects can absorb the heat they transmit. Dark colours absorb more radiant heat than lighter colours. This is why light coloured clothing is cooler than dark coloured clothing. This is the transfer of heat through a body or substance. Fireplaces conduct heat to the air as it comes into contact with the hot glass and firebox surface.