Lots of conservatories end up as storage rooms because they’re only comfortable for a few weeks a year. A modern split system works as a heat pump, so the same unit can cool the room in July and heat it in January. That’s why conservatories are one of the most common rooms we’re asked about.
It isn’t a guaranteed fix, though. Glass behaves very differently from an insulated wall, and there are building regulations and planning points to know about. Here’s the honest picture.
Why conservatories are hard to cool and heat
Sunlight passes through glass and warms everything inside, and the heat struggles to get back out. A south or west facing conservatory on a sunny afternoon can heat up very quickly. In winter, the same glass loses heat fast. There’s little thermal mass to even things out, so the room responds quickly to whatever the weather is doing.
The roof makes the biggest difference. A polycarbonate roof lets in much more heat than a tiled or solid insulated roof, and older glass roofs without solar control coatings are close behind. Blinds and shading help a lot and can mean a smaller, cheaper unit.
Sizing for glass, not floor area
Rules of thumb based on floor area don’t work for conservatories. At survey we look at:
- which way it faces and how much direct sun it gets through the day;
- roof type (glass, polycarbonate or solid) and the glazing specification;
- whether there are blinds, and whether you’ll use them;
- whether the doors to the house are usually open, which effectively makes the conservatory part of a bigger space;
- how you’ll use the room: an afternoon sitting room or a home office used all day.
An undersized unit runs flat out and still loses on hot afternoons. An oversized one costs more and cycles on and off. Our sizing guide explains why we work it out room by room.
Where the indoor and outdoor units go
The indoor unit needs a solid fixing. The best spot is usually the house wall the conservatory is built against, where the unit can sit high and throw air down the length of the room, and pipes can go straight through to the outside. A dwarf wall can work for some wall-mounted or floor-standing units, but we check its construction first. Units are never fixed to the glazing frames.
The outdoor unit usually goes on the ground or on brackets just outside. It needs the clearances set out in the manufacturer’s installation manual, a firm level base and a position that keeps noise away from your neighbours’ windows and your own seating area. Condensate from the indoor unit needs a route out, ideally by gravity to a drain or soakaway.
Want it done properly? AirCon Doctor installs, repairs and services air conditioning and heat pumps across London and the South East, from our base in East Grinstead. We’re an F-Gas certified company and NICEIC approved. Get a fixed-price quote.
Building regulations: keep the exemption
Many conservatories are exempt from building regulations. The Planning Portal’s page on conservatories and building regulations lists the conditions, and one of them is that there should be an independent heating system with separate temperature and on/off controls. A split system with its own controller fits that description. Extending your central heating into the conservatory is a different matter and can affect the exemption.
The other conditions still matter. The conservatory must stay separated from the house by external-quality walls, doors or windows, so if you take those out to open the conservatory up, it’s no longer treated as exempt.
The electrical side is notifiable work under Part P if a new circuit is added, unless it’s done by a registered competent person, as the Planning Portal’s electrics page explains. Our electrical work is covered by our NICEIC approval, so we certify it.
Planning permission
Since 2025, an air-to-air heat pump on a house can be permitted development in England if it meets the conditions set out on the Planning Portal’s heat pump planning page, including size, position and compliance with MCS 020(a). A unit used only for cooling isn’t covered by those rights, so if you only want cooling, check with your council. Listed buildings and conservation areas have extra rules.
Is it worth it?
If the room is unusable for much of the year, often yes. You gain a room you can actually use, and a heat pump can heat it more efficiently than an electric heater. If you’d only use it a few days a year, shading and ventilation may be enough.
A single-room split falls within our £1,200 to £2,200 + VAT range, including supply, installation, commissioning and F-Gas documentation. Your exact price depends on the unit size, the pipe run and the outdoor unit position. VAT on a domestic air-to-air system depends on the facts of the case under HMRC’s Notice 708/6, and we confirm it on your quote.
Quick answers
Can one unit heat and cool a conservatory?
Yes. Most modern split systems are heat pumps and can do both from the same indoor unit.
Will air conditioning affect my conservatory’s building regulations exemption?
A split system with its own controls counts as independent heating, which is one of the exemption conditions. Extending your central heating into the conservatory, or removing the doors to the house, can affect it.
Where does the indoor unit go in a conservatory?
Usually high on the solid house wall, never on the glazing frames. A dwarf wall can sometimes work for certain units after we check it.
Related services
- Air conditioning installation
- Wall-mounted air conditioning
- Air-to-air heat pumps
- Domestic air conditioning
More advice
- How to Choose the Right Size Air Conditioning Unit
- Do I Need Planning Permission for Air Conditioning in the UK?
- Air Conditioning for Garden Rooms and Outbuildings
- Air Conditioning in Winter: Using Heat Pump Mode Effectively
- All advice
This guide is general information, checked against the sources linked on 30 October 2026. It isn’t legal, tax or financial advice. Rules, grants and product ranges change, so check the current position before you rely on it.