Air conditioning guide
Air conditioning for conservatories
A conservatory is the room most people want to fix and the one that is hardest to size. Almost all of that comes down to glass.
Why conservatories are different
Every other room in the house has walls doing most of the work. A conservatory does not. Large areas of glazing let solar gain in during the day and let heat back out at night, which is exactly why these rooms swing from unusable in July to unusable in January.
That means the heat load of a conservatory is dramatically higher per square metre than an equivalent internal room. A conservatory can genuinely need more cooling capacity than a bedroom several times its size, which is the single most common surprise people get when they start asking.
It is also why a phone estimate is close to worthless for a conservatory. Floor area alone does not tell an installer enough.
What changes the answer
The roof
A polycarbonate roof, a glass roof and a solid or tiled replacement roof behave completely differently. A solid roof dramatically reduces solar gain, and if you are replacing the roof anyway it changes the air conditioning specification, so sequence the two decisions together rather than separately.
Which way it faces
A south or west-facing conservatory takes the afternoon sun and is the hardest case. North-facing is a different job entirely, and often a smaller one.
The glazing itself
Single, double, or solar-control glass makes a substantial difference, as does whether there is any existing shading — blinds, film, an overhang, or a tree. Existing shading reduces the capacity needed.
Whether it is open to the house
A conservatory separated by doors is a contained space to condition. One knocked through into the kitchen or living room is effectively one large space with a glass end, which changes both the sizing and where the indoor unit should go.
Where the indoor unit can go
This is the practical constraint people underestimate. A conservatory often has very little solid wall, and a wall-mounted indoor unit needs somewhere structurally suitable to be fixed — usually the dwarf wall or the house wall the conservatory joins.
Where there is genuinely no suitable wall, floor-standing or low-wall units exist and are worth asking about. Whatever the format, the unit still needs a route for pipework and, importantly, for condensate to drain away. Conservatories produce a lot of condensate when cooling humid air, and the drainage route is a question to settle at survey, not on the day.
What air conditioning will and will not fix
It will make a hot conservatory usable in summer, and if the system is a heat pump it will take the edge off in cooler months too.
What it will not do is compensate indefinitely for a conservatory that is fundamentally losing and gaining heat through its roof. If the room is uninhabitable at both ends of the year, it is worth pricing a roof replacement or upgraded glazing alongside the air conditioning rather than instead of asking about it. Sometimes the combination costs less to run and works better than a larger system fighting the building.
Planning and permissions
The conservatory itself is already there, so the question is only about the outdoor unit. That is usually straightforward, but conservation areas, listed buildings and flats are the common exceptions, and the position and size of the condenser are what matter. Your installer should advise, and your local council is the authority to confirm with.
Common questions
Will air conditioning make my conservatory usable in summer?
Generally yes, provided it is sized for the actual heat load rather than the floor area. The failures tend to be undersized systems specified without a proper look at the glazing, roof and orientation.
Do I need a bigger unit for a conservatory than for a normal room?
Usually, yes — often considerably bigger than the floor area alone would suggest, because the glazing drives the heat load. This is the main reason a conservatory needs a survey rather than a phone estimate.
Should I replace the conservatory roof instead?
It depends what you want. A solid or insulated roof substantially reduces solar gain and helps in winter too, but it does not actively cool. Many people end up doing both, with a smaller air conditioning system than they would have needed otherwise. If a roof replacement is on the table, decide it first.
Where does the indoor unit go if there is no wall space?
Usually on the dwarf wall or on the house wall the conservatory adjoins. Where neither works, floor-standing and low-wall units are worth asking about. The condensate drainage route needs settling at the same time.