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Air Conditioning Costs: Install and Running Costs Explained

Neutral living with air conditioning unit and lady holding air con remote
(Image credit: Getty Images)

Air conditioning costs will be at the forefront of your mind if you're currently weighing up whether to install it within in your home. A series of mini heatwaves have left us all reaching for ways to keep cool, and air conditioning is one measure to consider.

Cooling is being introduced to mechanical ventilation systems as well as many heat pumps being able to be run in reverse to add cooling to our homes. These systems can add a bit of cooling but when it comes to considering how to keep a house cool in summer, nothing has the same effect as proper air conditioning. Some units also add the potential for some heating in winter, too. 

It may appear to be an upmarket technology but just how much does air conditioning actually cost? And once installed, are the running costs astomical? Our expert guide is here to answer these questions and more.

Air Conditioning Costs: How Much Does it Cost to Install in One Room?

Fully installed air conditioning systems have an outdoor fan unit that is connected to indoor fan unit via refrigerant pipes and have a number of different configurations. The simplest fully installed air conditioning systems are known as room air conditioners (RAC) and there is one outdoor fan unit and one indoor unit.

These systems are usually for single room use and you can expect to pay from around £350 for the materials and around £1,100 to £1,500 for a fully installed system.

An advancement on the RAC unit is where there is one outdoor fan unit and two indoor units. Both indoor units serve a single room and they are both either on or off. You cannot usually operate the indoor units individually and they can only be in cooling or heating mode.

The exact specification of the indoor units will often be different between manufacturers and it is definitely worth getting a number of quotes for different brands.

How Much Does Whole-House Air Conditioning Cost?

The next step up is the multi split air conditioner — these systems have one outdoor fan unit and can have up to around 10 indoor units depending on manufacturer. The cost of a multi-split unit is usually around £1,200 per indoor unit.

The indoor units can be located in the same room or in separate rooms and can be operated individually or in any number up to the full installed amount. The indoor units can however only be in heating or cooling mode and therefore you cannot have some doing heating and some doing cooling.

The costs of multi split systems vary according to which indoor units you have and the simplest installation will usually be the wall-mounted bulk heads.

There are a number of different indoor units ranging from fan convectors that look a bit like a central heating radiator, wall-mounted bulk heads, to slim duct systems that can be boxed in and ducts installed to distribute the air. These units are popular because the fan noise is then further away from the point of delivery but there does need to be more design detail put in to define where the ducts go. This can all add cost. 

What is the Cheapest Air Conditioning Available?

The lowest cost air conditioning is the portable model. These units, as the name suggests, are portable and can be moved from room to room as required. The best portable air conditioners start at around £250 and have no installation costs.

A portable air conditioning unit start is around the size of a laundry basket will usually plug into a standard electric wall socket.

You will need to run a duct (approximately 125mm diameter) out a window to expel the warmth. The warm air must be expelled to the outside of the property so if there is no window or route outside then you will not be able to use these units. You will also need a bucket to run the condensate drain into. 

Arguably, the cheapest solution is avoid air con altogether by preventing our homes from overheating in the first instance. Building Regulations Part O (Overheating) was introduced in June 2022 to help mitigate against this. Albeit this looks at potential overheating in new properties, not existing properties, nor does it necessarily mean that cooling solutions are not required on the hottest day; as such air conditioning is still a viable choice.

Is Air Conditioning Expensive to Run?

Air conditioning units do use electricity so this does need to be taken into account. The air conditioning unit uses a refrigerant cycle to deliver cooling and the waste heat is rejected to the outside. The process allows for around 300% efficiency, meaning that if you use kWh of electricity you will get an equivalent 3kW of cooling.

Taking the average air conditioning indoor unit at around 2kW you will use around 600W of electricity. At around 28p/kWh expect the air conditioning to cost around 20p per hour per indoor unit. 

If you also have solar PV (photovoltaic) panels then you have the ideal combination as you will be generating the most electricity at the time when cooling may be required and your running costs will be a lot less.

What Should I Look for in an Installer?

Make sure that your installer is FGas qualified and registered with a self certification body (meaning that can deal with the Building Regulations). 

A fully installed air conditioning system must also be inspected every five years to assess its energy efficiency, so factor this cost in when considering introducing air conditioning to your home.

David is a renewables and ventilation installer, with over 35 years experience, and is a long-standing contributor to Homebuilding and Renovating magazine. He is a member of the Gas Safe Register, has a Masters degree in Sustainable Architecture, and is an authority in sustainable building and energy efficiency, with extensive knowledge in building fabrics, heat recovery ventilation, renewables, and also conventional heating systems. He is also a speaker at the Homebuilding & Renovating Show. 

Passionate about healthy, efficient homes, he is director of Heat and Energy Ltd. He works with architects, builders, self builders and renovators, and designs and project manages the installation of ventilation and heating systems to achieve the most energy efficient and cost effective outcome for every home.