Radiant ceiling under a covered terrace in Rodez

Heating a volume that is not closed

A covered terrace has no walls on at least one side. Heating the air there is pointless: it leaves. It is the one configuration where radiation is not merely preferable, it is the only physically defensible answer, because it reaches people without going through a fluid that escapes.

What can be expected, and what cannot

You can make a terrace usable in the shoulder seasons, and extend its use by several weeks either side of summer. You cannot hold it at twenty degrees in January with the wind blowing through. The limit is the wind, not the power.

The part played by the roof

With no ceiling there is no substrate and no plenum. The stretched fabric provides both: it gives a continuous emitting surface and closes the volume above, which stops the heat produced being lost into the structure.

The orientation of the surfaces

On a terrace, the open side is also the side through which radiation escapes to a cold sky. The layout of the emitters is therefore thought out according to where people actually settle, and not uniformly as in a closed room.

The question of commercial use

On a restaurant terrace, outdoor heating is regulated in France and the rules change from time to time. A system built into a roof is not treated like a patio heater, and the point is worth checking with the local authority before the design stage.

Large volumes are dealt with on the page about high ceilings, and the system on the heated radiant stretch ceiling page.