Can a rooflight or skylight open automatically on temperature?

Yes. A temperature input on the controller, either a dedicated thermostat or a rule in a home automation system, will open the rooflight when the room passes a set point and close it when it falls back. Paired with a rain sensor, that gives a kitchen that ventilates itself on a hot afternoon when nobody is at home.

What it actually solves

The empty house in July.

The hours when a south facing kitchen gets hottest are usually the hours when nobody is in it, which is exactly when a manual rooflight stays shut.

Automation covers the gap.

How it is done simply

A thermostat wired to the controller. A room thermostat with a switched output tells the controller to open above a set temperature and to close below it, and nothing else is needed.

How it is done in a smart house

A rule rather than a device. Where the rooflight is integrated into a home system, the same behaviour is a rule alongside the lighting and heating, and it can take account of time of day as well.

The integration options are on how is an electric rooflight controlled.

Where the sensor should be

In the room, out of direct sun.

A thermostat in a sunbeam reads the sun rather than the room, and it will open the rooflight on a cold bright February morning.

Position is most of whether it behaves sensibly.

Setting the set point

Higher than you would expect. A set point close to comfortable temperature has the rooflight opening and closing repeatedly, and a point a few degrees above it opens only when it is genuinely needed.

Hysteresis

The setting that stops it cycling. A gap between the opening and closing temperatures prevents the unit hunting up and down as the room passes the threshold, and most controllers provide it.

Rain wins

The interaction that makes it usable. Where both are fitted, the rain sensor overrides the temperature control, so a hot afternoon that turns to a shower closes the unit regardless.

What it does is on what is a rain sensor rooflight.

Whether it reopens after rain

Depends on the system, and it is worth setting deliberately.

Some will resume automatic operation once the sensor dries, and some hold closed until somebody intervenes, which is the safer default.

Partial opening on temperature

Available on better systems. Opening to a preset partial position rather than fully is often what a room wants, and it reduces the draught and the security question at once.

Night cooling

Where automation is genuinely valuable. A rule that opens the rooflight overnight when the outside temperature has dropped flushes the day’s heat out of the room and the structure before morning.

What that does is on how much ventilation does an opening rooflight give.

Security overnight

The reason to think about it rather than just set it.

An opening left unattended on a low roof is a consideration, and a limited stroke or a restricted position is the usual answer.

Humidity instead of temperature

Sometimes the more useful input.

In a bathroom or a utility, opening on humidity rather than on temperature is what the room actually needs, and controllers that take a humidity sensor exist.

Interaction with the heating

Worth thinking about in a smart house.

A rooflight opening while the heating is running is a waste, and a rule that checks the heating state before opening avoids it.

What happens in a power cut

Nothing, and that is worth planning for.

An automatically opened rooflight left open by an outage cannot close itself, which is an argument for a battery backup on any automated unit.

That is on can an electric rooflight be opened in a power cut.

Whether it can be overridden

Always, on any sensible system.

Manual commands from a switch or a handset take priority, and the automation resumes afterwards or waits, depending on how it is configured.

Two units on one rule

Better ventilation and one setting. Where two rooflights are grouped, a single temperature rule opens both and gives cross ventilation rather than a single point of escape.

That is on can two rooflights open together.

Where it is not worth it

A landing or a hallway. Automation earns its keep in a room that overheats or gets humid, and on a stairwell rooflight it is a solution without a problem.

What it costs

A thermostat and some configuration. Where the controller already supports it, the addition is small, and where the system has to change it is a larger decision.

Where it sits is on how much does an electric rooflight cost.

Seasonal settings

Worth changing twice a year rather than setting once.

A set point that suits July is wrong in October, and most systems make it a two minute change that stops the rooflight opening on a mild autumn afternoon.

What happens when nobody adjusts it

The commonest reason automation gets switched off.

A rooflight opening at times the household does not expect is turned off at the wall and never turned back on, which is a settings problem being read as a product one.

Ten minutes at handover prevents it.

How we set it out on an opening unit

We set the temperature control up with the rain sensor at commissioning and we show the homeowner how to change the set point, because the default will not be the number their room wants.

The whole picture is on the electric rooflight installation page.