It can produce about 2 watt of light and 98 watt of heat. Also asked how much does it cost to run a 100 watt heat lamp. What Is Light Bulb Heat Temperature Chart How Hot Can A Light Bulb Be The outside surface of an LEDs light bulb is usually half the temperature of an equivalent Incandescent or Halogen bulb. . In other words it produces about 2 watts of light and 98 watts of heat. How much heat does a light bulb produce. So a 100-watt bulb would only cost 084 per hour if. If the room is small light bulbs will heat it up. According to the Wikipedia online encyclopaedia a 100 watt bulb is 21 efficient. H 352000 J. For every 100 watts you put in you get about 35 watts of light and 965 watts of heat. For every 100 watts you put in you get about 35 watts of light and 965 watts of heat. The heat makes the filament white-hot producing the light that you see. Similarly which light bulbs give off