For the purposes of temperature control in places with extremely tight environmental requirements, the modelling assumption is that a human being gives off the

For the purposes of temperature control in places with extremely tight environmental requirements, the modelling assumption is that a human being gives off the same amount of thermal energy as a standard 100-watt incandescent lightbulb. When you check into the clean room, you turn off your bulb. When you leave you turn it back on. The bulbs also serve as a handy way to tell who is in the lab that day :)