Being physicists they were presumably aware of Wein's Law that gives the peak wavelength emitted by a hot (black) body. ~ 2900/T micrometers, where T is the temperature in Kelvin.Saw some oil filled heating panels in a school once. On the ceiling.
Someone had painted them white. They were in a physics lab.
The ceiling radiation would peak at about 10μm, well into the infra red, where white paint is nearly equilavent to a black body for radiation emissivity.
No, they don't need to be fan assisted. They are like a radiant heater except that the whole ceiling is a heat emitter instead of a thin bar, so the heating is much more effective.
