How to Keep a Conservatory Warm in Winter and Cool in Summer

Learning how to keep a conservatory warm in winter, and cool in summer, is what turns a room you avoid for half the year into space you use every day. Most UK conservatories share the same fault: a glass or thin polycarbonate roof that lets heat pour out in December and bake the room in July. The good news is that every part of the problem has a fix, from a one-off roof upgrade to cheap tweaks you can make this weekend. This guide runs through them in order of impact so you spend money where it counts.

If you are weighing up a bigger change, our guides across the Contemporary Structures site cover conservatory roofs, glazing and heating in more detail.

Table of Contents

Why conservatories overheat and lose heat

A conservatory is mostly glass, and glass is a poor insulator. Heat escapes fastest through the roof, because warm air rises and an old polycarbonate roof has almost no thermal resistance. Single or early double glazing in the frames leaks more, and an uninsulated floor and dwarf walls add to the loss. In summer the same glass acts like a greenhouse, trapping solar gain until the room is unusable. Tackle the roof and the glazing and you fix both problems at once.

Fixing the roof: the biggest single change

The roof is where most of the heat moves, so it is the highest-impact upgrade. There are three common routes:

A solid or tiled replacement roof: swapping glass or polycarbonate for an insulated, tiled roof gives the biggest improvement, turning the conservatory into something closer to a proper room with a plastered, insulated ceiling. It usually needs building regulations approval and can reduce natural light, so it is the most involved option.
Internal roof insulation panels: insulated boards fitted under the existing roof with a new plastered or clad ceiling. Cheaper than a full replacement and quick to fit, though you lose the view of the sky.
Modern glass roof upgrade: replacing tired polycarbonate with self-cleaning, solar-control glazing keeps the light but improves comfort far less than a solid roof.

Because a tiled or solid roof changes the structure and thermal performance, it typically falls under building control. The Planning Portal sets out when conservatory work needs building regulations approval, which is worth checking before you commit.

Glazing, blinds and shading

After the roof, the glass in the frames matters most. If the conservatory still has old double glazing, upgrading to modern units with a low-emissivity (low-E) coating reflects heat back into the room in winter and blocks some solar gain in summer. Solar-control glass in the roof or elevations makes a noticeable difference to summer overheating.

Blinds are the cheaper half of the job. Pleated or cellular (honeycomb) blinds trap a layer of air and cut heat loss through the glass at night, while roof blinds and external shading keep the worst of the summer sun out. External shutters or an awning work better than internal blinds in summer, because they stop the heat before it passes through the glass.

Heating a conservatory in winter

Once you have reduced the heat loss, a modest heat source will hold the room at a comfortable temperature. Options include:

Electric underfloor heating: a popular retrofit under a new tiled floor, giving gentle, even warmth without radiators taking up wall space.
Electric radiators or panel heaters: simple to fit and control room by room, ideal if you do not want to extend the wet central heating system.
Extending the central heating: adding a radiator on the existing system is efficient, but this can affect the conservatory’s building regulations exemption (see below), so it needs thought rather than a quick DIY spur.

Whatever the heat source, an insulated roof and floor are what let it work; heating an uninsulated glass box just sends money out through the roof.

Insulating the walls and floor

The dwarf walls (the low brick walls under the glazing) and the floor are easy to overlook. Insulating the floor when you re-lay it, and making sure the dwarf walls are properly built and insulated, cuts the draughts and cold surfaces that make a room feel colder than the thermostat says. Draught-proofing the doors and sealing gaps around frames is a cheap, high-value finishing job.

Ventilation is the other half of summer comfort. Trapped hot air needs somewhere to go, so trickle vents in the frames, opening roof vents or a roof lantern that opens, and simply cross-ventilating with doors and windows on opposite sides all help the room shed heat on a hot day. Pairing good shading with a way for hot air to escape is far more effective than shading alone, and it costs little to add when you are already upgrading the glazing.

Do building regulations affect conservatory heating?

Many conservatories are exempt from building regulations because they are single-storey, under 30 square metres, at ground level, separated from the house by external-quality doors, and either unheated or heated on their own independent controls. Extend the home’s central heating into the conservatory, or remove the separating doors to open it fully to the house, and you can lose that exemption, which may mean the work needs building control sign-off and has to meet energy efficiency standards. It is not a reason to avoid heating the room; it is a reason to plan the heating properly and check the rules first. Always confirm your specific case with your local authority building control.

Frequently asked questions

What is the cheapest way to keep a conservatory warm?

Start with draught-proofing, thermal or cellular blinds on the glass, and a portable electric heater. These cost little and cut the worst of the heat loss. For a lasting fix, insulating or replacing the roof gives by far the biggest improvement.

Does a new conservatory roof really make a difference?

Yes. The roof is where most heat is lost, so replacing polycarbonate or glass with an insulated or tiled roof, or fitting internal insulation panels, is the single most effective change for both winter warmth and summer comfort.

Why is my conservatory so hot in summer?

Glass traps solar gain, and a clear roof lets the sun heat the room like a greenhouse. Solar-control glazing, roof blinds and external shading or an awning block the heat before it builds up, and better ventilation lets it escape.

Can I put underfloor heating in a conservatory?

Yes. Electric underfloor heating is a common retrofit under a new tiled or stone floor and gives even warmth without radiators. It works best once the roof and floor are insulated, so the heat is not wasted.

Do I need building regulations to heat my conservatory?

A conservatory is usually exempt if it is small, separated from the house by external-quality doors and heated independently. Extending the central heating into it or removing the separating doors can end that exemption, so check with building control before you start.

Are thermal blinds worth it for a conservatory?

Pleated or cellular blinds trap a layer of air against the glass, reducing heat loss at night in winter and blocking some sun in summer. They are an affordable improvement, though they work best alongside better glazing or an insulated roof.

How to Keep a Conservatory Warm in Winter and Cool in Summer

Why conservatories overheat and lose heat

Fixing the roof: the biggest single change

Glazing, blinds and shading

Heating a conservatory in winter

Insulating the walls and floor

Do building regulations affect conservatory heating?

Frequently asked questions

What is the cheapest way to keep a conservatory warm?

Does a new conservatory roof really make a difference?

Why is my conservatory so hot in summer?

Can I put underfloor heating in a conservatory?

Do I need building regulations to heat my conservatory?

Are thermal blinds worth it for a conservatory?

Related guides