# Loft Conversion Air Conditioning | Cost and Options

> Air conditioning for a loft conversion, from 1,900 pounds fitted. Why a loft needs about 30 percent more output, and where the outdoor unit actually goes.

*Climate Shield London — https://climateshieldlondon.co.uk/loft-conversion-air-conditioning/. Verbatim from the page; this is the same content, not a summary.*

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![Air conditioning outdoor unit on brackets high on a rendered wall, with a ladder in position for access](https://climateshieldlondon.co.uk/assets/img/jobs/job-18-1200.webp)

# Loft conversion air conditioning

A loft conversion is reliably the hottest room in a London house, and it is hot for three reasons at once: the roof above it, the heat rising into it from the rest of the house, and insulation that was designed to keep warmth in during winter.

- Free survey and a fixed written price
- Sized from a calculation, not from the floor area
- One day on site for most single rooms

Call 07976 704160 [WhatsApp us](https://wa.me/447976704160?text=Hi%20Climate%20Shield%2C%20I%20would%20like%20a%20quote%20for%20air%20conditioning%20in%20a%20loft%20conversion.)

## Book a free survey

We come out, measure, and send a written price. No charge, no obligation, and no deposit before you have seen the number.

## Brands we work with

![Daikin](https://climateshieldlondon.co.uk/assets/img/brands/daikin.ce47c11f.webp) ![Mitsubishi Electric](https://climateshieldlondon.co.uk/assets/img/brands/mitsubishi-electric.2977d309.webp) ![Samsung](https://climateshieldlondon.co.uk/assets/img/brands/samsung.3b6b3325.webp) ![Bosch](https://climateshieldlondon.co.uk/assets/img/brands/bosch.7d80a7ce.webp) ![Vaillant](https://climateshieldlondon.co.uk/assets/img/brands/vaillant.573f9864.webp)

A loft conversion needs roughly 30 percent more cooling output than the same room on a lower floor. A typical 16 square metre loft bedroom needs 3.5kW and costs 1,900 to 2,800 pounds fitted, including VAT.

The harder question is usually not the indoor unit. It is where the outdoor unit goes and how the pipework gets there.

## What size a loft conversion needs

Using the same model as the sizing calculator on this site, which applies a 30 percent uplift for a loft on top of the aspect and glazing adjustments.

| Room | How it works out | Unit |
| --- | --- | --- |
| Small loft room, 12 m², north facing | 12 × 0.14 = 1.68, less 10% aspect, plus 30% loft | 2.5kW |
| Loft bedroom, 16 m², east facing | 16 × 0.14 = 2.24, plus 30% loft | 3.5kW |
| Loft bedroom, 16 m², south facing | 2.24, plus 18% aspect and 30% loft | 3.5kW |
| Loft with large dormer glazing, 18 m², west | 2.52, plus 18% aspect, 18% glazing, 30% loft | 5.0kW |
| Loft home office, 14 m², south facing | 1.96, plus 18% aspect, 12% office use, 30% loft | 3.5kW |

## Why the sloped ceiling is the real constraint

A wall-mounted indoor unit needs a run of vertical wall, roughly 800 to 1,100mm wide and around 300mm tall, with clear air above and below it and somewhere for the condensate to fall away. In a loft conversion a great deal of the wall is not vertical, and what is vertical is often the dormer, the gable end, or the low knee wall that is too low to be useful.

So the survey on a loft starts with where the unit can physically go rather than with how much output it needs. Where there is no good wall, the answers are a slim ducted unit in the eaves void discharging through a grille, or a unit on the gable wall with a longer indoor pipe run.

Getting that decided before the plasterer finishes is worth real money. Air conditioning specified during a loft conversion is straightforward; air conditioning added to a finished loft two summers later usually means a surface pipe run somebody then wants boxed in.

## Where the outdoor unit goes, which is the expensive question

The indoor unit is at the top of the house and the outdoor unit is nearly always at the bottom of it, so a loft installation has the longest pipe run of any domestic job. The first eight metres are included in our pricing and after that it is 40 pounds a metre, which on a three-storey London terrace is a real line on the quote.

The alternatives are a flat roof if the conversion created one, which is usually the best answer and needs a frame and load spreading, or a high-level wall bracket, which needs safe access for the installation and for every service afterwards.

That access question is the one people underestimate. A unit that needed a tower to install will need one again in five years, and a position that saves 300 pounds now can cost more than that every time it is serviced.

## Heating it in winter, which is the part nobody costs in

A loft conversion is usually at the end of the heating system, on the longest pipe run from the boiler, and very often has one radiator that was sized optimistically. It is the coldest room in February as reliably as it is the hottest in July.

The same air conditioner heats. A modern unit running in heating mode delivers roughly three to four units of heat for every unit of electricity, which makes it cheaper to run than an electric panel heater by a wide margin and competitive with gas at current prices.

That changes the value of the installation considerably, and it is the single most under-used capability of every system we fit. Most owners never press the heat button.

## What it costs

| Scope | System | Installed price |
| --- | --- | --- |
| Loft bedroom | 2.5 to 3.5kW wall unit | £1,900 to £2,800 |
| Large loft or dormer room | 5.0kW wall unit | £2,300 to £3,600 |
| Slim ducted, hidden in the eaves | Grilles only, unit concealed | Add £700 to £1,400 |
| Pipe run over 8 metres | Common on a three-storey house | Add £40 per metre |
| Scaffold or tower access | Where there is no safe ladder position | Add £300 to £700 |

Every figure on this site is an estimate based on published UK market ranges and our own installation experience. It is not a quotation. The price you are given after the free survey is the price you pay.

## Other rooms

[Bedrooms A bedroom is the hardest room in the house to get right, and not because it is difficult to cool. Bedrooms](https://climateshieldlondon.co.uk/bedroom-air-conditioning/) [Conservatories A conservatory is the one room where we will sometimes tell you not to buy air conditioning yet. Conservatories](https://climateshieldlondon.co.uk/conservatory-air-conditioning/) [Home offices A home office is a small room with a person and several hundred watts of electronics in it, occupied for eight hours at exactly the time of day the sun is on the building. Home offices](https://climateshieldlondon.co.uk/home-office-air-conditioning/) [Size any room The calculator behind every figure on this page, in kW and BTU, with the working shown. Sizing calculator](https://climateshieldlondon.co.uk/what-size-air-conditioning-do-i-need/)

### Get a price for this room

Tell us the room and the postcode. We come out, measure, and send a fixed written price. No charge and no obligation.

### Not sure what size?

The sizing calculator gives a well-founded starting point in about a minute.

[Work out the size](https://climateshieldlondon.co.uk/what-size-air-conditioning-do-i-need/) Call 07976 704160

## Loft conversions: common questions

### Does a loft conversion need planning permission for air conditioning?

On a house, usually not. A domestic installation that meets all the Class G permitted development conditions needs no application, and those conditions are about the size of the unit, where it sits and how close it is to a boundary rather than about which floor it serves. Every condition is on the [planning page](https://climateshieldlondon.co.uk/air-conditioning-planning-permission/).

Two things change that. Inside a conservation area the unit cannot go on a wall or roof slope fronting a highway, which matters more on a loft because high-level positions are more visible. And in a flat, permission is always required.

### Why does a loft need a bigger unit than the same room downstairs?

Because it has the roof directly above it, absorbing sun all day and re-radiating into the room, and because warm air from the rest of the house rises into it. Our sizing model adds 30 percent for a loft, and in a west-facing loft with a large dormer the combined uplift can be over 60 percent.

It is also why a loft is the room where under-sizing shows up fastest. A unit that would be ample downstairs simply never catches up under a roof in August.

### Can you fit it into a loft that is already finished?

Yes, and most of the ones we do are. The question is the pipe route: whether it can go internally through a cupboard, a void or a boxed corner, or whether it runs on the outside of the building and gets boxed and made good.

Both are normal. What we will not do is decide it on the day, because that is how a surface pipe ends up somewhere the owner would not have agreed to.

### Will it heat the loft in winter too?

Yes, and in a loft that is often the more valuable half. Air conditioners are heat pumps, they run in reverse, and they deliver roughly three to four units of heat per unit of electricity.

For a loft room at the far end of the heating system with one undersized radiator, that is usually a bigger improvement than the cooling is.

## Free survey for a loft conversion

We measure the room, do the heat load calculation properly, and give you a fixed written price with the model on it. If a smaller unit is the right answer, we will tell you.

Call 07976 704160 [WhatsApp us](https://wa.me/447976704160?text=Hi%20Climate%20Shield%2C%20I%20would%20like%20a%20quote%20for%20air%20conditioning%20in%20a%20loft%20conversion.)

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