A conservatory is the room people most often describe as unusable, and the room where cooling makes the most dramatic difference. It is also the hardest room in the house to get right, which is why so many people have tried something already and been disappointed. Here is what genuinely works.
In this guide
Why a conservatory is the hardest room in the house
Everything that makes a conservatory pleasant also makes it difficult. It is a glass box attached to the side of a house, with very little in it that can hold a temperature.
In an ordinary room, brick and plaster act as a buffer. They soak up heat slowly and give it back slowly, which is why a normal room takes hours to warm up. A conservatory has almost none of that. Sun comes through the glass, the room heats up within the hour, and by mid afternoon it is a greenhouse. Then the sun goes down and it dumps that heat straight back out through the same glass. Unbearable in July, freezing in January.
What does not work
Most people arrive at air conditioning having tried something else first. Why those things fall short is worth being honest about, because it is the same reason air conditioning succeeds.
- Opening the doors and windows. Free, and it helps a little on a breezy day. On a still, hot afternoon you are letting warm air swap places with warm air.
- Fans. A fan does not cool a room. It moves air across your skin, which feels cooler, and the motor adds a little heat. Better than nothing while you sit in front of it, and nothing at all for the room.
- A portable air conditioner. The most common disappointment we hear about. It has to vent hot air somewhere, usually through a hose in a partly open door, which lets warm air back in. It is noisy, it takes floor space, it needs emptying, and it is working against a leak you created for it.
- Electric heaters in winter. They produce heat, and they are the most expensive way to do it. In a room that loses heat as fast as a conservatory, you can run one all evening and still feel it near the glass.
- Doing nothing. What most people settle for, and why a lot of conservatories are a storage cupboard for eight months of the year.
What does work
A properly sized, fixed system works, because it does not have the compromise built into it that the portable one does. The outdoor unit sits outside where it belongs, connected by pipework rather than a hose through a gap in the door. Nothing is let back in. The heat comes out of the room and stays out. That single difference is why a fixed system and a portable unit are not really the same category of product, whatever the box says.
The other half is that the systems we fit are reverse cycle, so the same box that cools the room in July heats it in January, at roughly a third of what an electric heater costs for the same warmth. For a conservatory that is not a bonus feature. It is the reason the room becomes usable all year.
Sizing a conservatory is its own problem
If you take one thing from this article, take this. A conservatory needs considerably more capacity than a normal room of the same floor area, and anyone who prices it like a bedroom has not understood the room.
The heat load is driven overwhelmingly by the glass. How much there is, which way it faces, whether it is double glazed, whether it has any solar control coating, and whether the roof is glass, polycarbonate or solid. Those move the answer far more than floor area does.
This is why sizing a conservatory from a rule of thumb goes wrong so reliably. Our guide on what size unit you need explains the calculation in general, but this is the room where skipping it hurts most. An undersized unit here does not underperform slightly. It runs flat out all afternoon and you are still too warm, which feels like the technology failed when in fact the specification did.
Where the indoor unit goes
Air conditioning needs a wall, and a conservatory is mostly not walls. Usually the answer is the dwarf wall that runs around the base, or the solid wall the conservatory is built against. Both are workable. A low wall or floor standing unit is often the sensible choice, because it is designed to sit at that height and throw air upwards across the room rather than down at your head.
The other thing that has to be planned rather than assumed is the condensate drain. The system pulls a lot of moisture out of the air in a conservatory, and that water has to go somewhere sensible. In a room on a slab with no drain nearby, that is a design question rather than a detail, and one we work out at survey rather than on the day.
Winter is half the reason
Most people call us about a conservatory in July, then tell us afterwards that the winter surprised them more.
The reason is straightforward. A conservatory loses heat quickly, so heating it with plug in electric heaters means paying the worst possible rate for warmth in the room that needs most of it. A fan heater gives you one unit of heat for one unit of electricity, and that is its ceiling. A reverse cycle system gives you roughly three.
In a room you previously heated electrically, that is a large difference every time you use it. It is why plenty of our customers describe the conservatory as the room that finally became part of the house.
What air conditioning will not fix
Better to set the expectation properly than have you find out afterwards.
- It will not make a badly built conservatory well built. If the frames leak or the roof is failing, the system fights that every day and you will feel it near the glass.
- It will not stop the sun coming in. It removes the heat once it is there. Keeping some out in the first place is free and makes the system’s job much easier.
- It does not ventilate. A split system recirculates the air already in the room. You will still want the doors open on a nice day, and that is fine.
- It only serves that room. A unit in the conservatory does nothing for the kitchen it opens onto unless the design accounted for that too.
- It will not run for free. A conservatory is a hard room and it uses more energy than a bedroom. Still far cheaper than the electric heater it replaces, but not nothing.
Blinds, glass and roofs
A small amount of work on the room itself makes the system smaller and cheaper, and this is advice that costs us money to give, which is roughly how you know it is honest.
Blinds, particularly on the roof and the sunny side, cut solar gain before it becomes your problem. If you are replacing glazing anyway, solar control glass is worth asking about. And a solid or insulated roof replacement changes the room more than anything else here, in both directions. It cuts the summer heat and holds the winter warmth.
None of these replace cooling. A conservatory with the best blinds in the world is still a glass box in August. But every bit of gain you keep out is capacity you do not have to pay for, so mention it at survey if you are planning any of it.
The door question
People ask whether to leave the door to the house open. For cooling the conservatory, no. With the door open you are cooling the conservatory, the kitchen and a share of the rest of the house through a unit sized for one room. It will not keep up.
If you want the whole open plan space comfortable, that is a fair thing to want. It is also a different design with different capacity, so tell us at survey rather than discovering it in August.
Conservatories across Teesside
Conservatories are everywhere across Teesside, on the estates around Ingleby Barwick and Eaglescliffe, on the semis in Marton and Norton, and on the older housing around Middlesbrough and Thornaby. The story we hear is nearly always the same. It was a great idea, and it is unusable for half the year.
We survey for free, at your home, and we will tell you honestly what the room needs. If we think you would be better off spending the money on the roof first, we will say so. We are on North Ormsby Road in Middlesbrough and cover around twenty miles of Teesside, from Stockton on Tees and Thornaby across to Yarm, Redcar, Guisborough, Hartlepool and Darlington. Give us a ring on 01642 680 873.
