Another way of looking at it is: If you have 75 watts of power
into the room, and nothing going out, the room will heat up. It
matter whether it is a toaster, a light bulb, a space heater, a TV
or an electric toothbrush. What matters is the amount of power going
into a sealed room..... It ALL turns into temp rise unless there is a
some part of it to radiate out.......
Andy in Eureka, Texas
PS I do not endorse using a 75 watt toothbrush as a