Temperature checks on a radiant stretch ceiling in a bathroom

Why measure rather than assert

Felt comfort is subjective, and a discussion about comfort quickly goes round in circles. A temperature reading does not settle everything, but it moves the conversation towards something checkable, which is already considerable in a field where everyone has an opinion.

Where to place the measuring points

At floor level, at ankle height, at seated height, at head height and at the ceiling. It is the vertical distribution that counts, not the value in the middle of the room. A convection system shows a marked gap between floor and ceiling; a radiant system shows a flat curve.

When to take the readings

After complete stabilisation, several hours after switching on, and noting the outside temperature at the time. A measurement taken during warm-up says nothing, except that the system is warming up.

What to look at besides the figures

The temperature of the surfaces, with a camera or an infrared thermometer. That is what decides how it feels, more than the air temperature, and it is what explains why a room at twenty degrees can be uncomfortable.

The particular case of a bathroom

One point is added: the temperature of the coldest surface, usually the external wall or the mirror. That is where condensation will form, and therefore the point that decides how damp the room is.

A reading of the same kind in an RT 2012 house is presented on the page about that visit, and the thermal camera check on the page about measuring a heated ceiling.