Knowing how to choose an air conditioner comes down to matching the right size unit to your room, picking the correct type of system for your property, and balancing efficiency against upfront cost. Get any one of these wrong and you’ll end up with a unit that’s noisy, inefficient, or simply not powerful enough to cool the space properly.
This guide walks through every factor worth considering, tailored for homeowners across the North West, Yorkshire and the Midlands weighing up their first air con installation.
How Do You Choose An Air Conditioner?
You choose an air conditioner by working through a handful of key decisions in order, starting with room size and required cooling capacity, then moving on to unit type, efficiency rating, noise level and budget.
Getting the capacity right matters most, since an undersized unit will run constantly without ever properly cooling the room, while an oversized one cycles on and off too quickly, wasting energy and failing to remove humidity effectively.
Once capacity is sorted, the rest of the decision becomes about matching features and price to how you’ll actually use the air con unit day to day.
What Size Air Conditioner Do You Need For Your Room?
The size air conditioner you need for your room depends on its floor area, with a widely used UK rule of thumb being roughly 100 to 140 BTUs, or 0.03 to 0.04kW, per square metre of space before adjusting for other factors.
| Room Size | Recommended Capacity |
| Up to 15m² (small bedroom) | 5,000-7,000 BTU (1.5-2.0kW) |
| 15-25m² (average bedroom, small living room) | 7,000-9,000 BTU (2.0-2.5kW) |
| 25-35m² (large bedroom, average living room) | 9,000-12,000 BTU (2.5-3.5kW) |
| 35-50m² (large living room, open plan area) | 12,000-14,000+ BTU (3.5-4.0kW+) |
These figures need adjusting for your specific room though. Add around 10 percent capacity for south facing rooms that get more direct sun, subtract roughly 10 percent for heavily shaded, north facing spaces, and add extra capacity for kitchens or rooms regularly holding more than two people, since both cooking appliances and body heat add to the cooling load.
Which Type Of Air Conditioning Unit Should You Choose?
The type of air conditioning unit you should choose depends on how many rooms you want to cool and how much disruption you’re willing to accept during installation.
- A single split system, with one indoor unit connected to one outdoor condenser, suits most single room installations like a bedroom or home office.
- A multi split system connects two to five indoor units to a single outdoor condenser, a sensible choice for family homes across the Midlands wanting several rooms cooled without cluttering an exterior wall.
- Ducted systems hide the indoor unit in a ceiling void for a completely discreet finish, though they involve more disruptive installation and a higher upfront cost, making them better suited to larger renovation projects than a straightforward retrofit.
Should You Choose A Portable Or Fixed Air Conditioner?
You should choose a fixed split system air conditioner over a portable unit if you plan to use air con regularly, since fixed units are considerably more efficient, quieter and longer lasting than portable alternatives.
Portable air conditioners typically last 8 to 12 years compared to 15 to 20 years for a properly installed split system, and they’re noticeably noisier since the compressor sits inside the room rather than outside in a condenser unit.
How Important Is Energy Efficiency When Choosing An Air Conditioner?
Energy efficiency is genuinely important when choosing an air conditioner, since a higher SEER and SCOP rating directly reduces your running costs over the unit’s lifetime, often enough to offset a higher purchase price within a few years.
Premium brands like Daikin and Mitsubishi Electric commonly reach A+++ ratings with SEER figures above 8.5, while more budget focused brands like Midea and Gree tend to sit at A++ or A+, still efficient but using somewhat more electricity for the same output.
For anyone planning to run their unit frequently across both summer cooling and winter heating, paying a bit more for a genuinely efficient model usually pays for itself over time.
How Much Does Noise Level Matter When Choosing An Air Conditioner?
Noise level matters considerably when choosing an air conditioner, particularly for bedroom installations where a unit running overnight needs to stay genuinely unobtrusive. Premium models from Mitsubishi Electric and Daikin can reach as low as 18 to 19 decibels on their quietest setting, while some budget models sit closer to 22 decibels, a difference that’s noticeable in a quiet room at night even though both figures sound low on paper.
If the unit is going in a bedroom or a room used for concentrated work, it’s worth specifically checking the manufacturer’s quoted noise level rather than assuming all air con units sound roughly the same.
What Features Are Worth Considering When Choosing An Air Conditioner?
The features worth considering when choosing an air conditioner include smart app control, self cleaning functions, and reversible heating capability, all of which add genuine day to day value beyond basic cooling.
Smart app control lets you schedule and adjust your unit remotely, useful for warming or cooling a room before you arrive home. Self cleaning coil functions reduce maintenance hassle and help prevent mould build up inside the unit.
A reversible heat pump function, standard on most modern models, effectively gives you winter heating alongside summer cooling, meaningfully improving the value proposition of the whole installation.
What Does It Cost To Install An Air Conditioner?
It costs between £1,500 and £2,700 to install a single split air conditioning unit in the UK, rising to £2,800 to £7,000 for a multi split system covering several rooms, depending on brand, capacity and installation complexity. Running costs for a standard single room unit typically sit between 17p and 30p per hour, making day to day use more affordable than many homeowners expect once they get a proper quote.
Choosing a reputable, certified installer matters just as much as choosing the right brand, since correct sizing and quality fitting has a bigger impact on long term performance and running costs than brand alone.
Get A Free Air Conditioning Installation Quote Today
Not sure which air conditioning unit is right for your home? Clever Energy Boilers provides expert air conditioning installation throughout the North West, Yorkshire and the Midlands, and our certified engineers can help you choose the correct size, type and brand for your property. Get in touch today to request your free, no obligation air conditioning installation quote.
FAQs
Can you install different sized air conditioning units in different rooms of the same multi split system?
Yes, a multi split system allows each indoor unit to have a different capacity, so you can match each room’s specific cooling needs from a single shared outdoor condenser.
Does the colour of a room’s walls or curtains affect the air conditioner size needed?
Wall and curtain colour has minimal direct impact on sizing, though rooms with large uncovered glass areas typically need more cooling capacity than those with heavier curtains blocking direct sunlight.
Is it better to choose an air conditioner with a higher capacity than calculated as a safety margin?
No, oversizing an air conditioner beyond the calculated requirement typically causes it to short cycle, reducing both efficiency and its ability to properly remove humidity from the room.
Can an air conditioner be too quiet to notice it’s actually working?
No, even the quietest air conditioning units at 18 to 19 decibels still circulate air effectively and cool the room properly, since noise level relates to sound output rather than cooling performance.
Should you choose an air conditioner based on the brand of your existing boiler or heating system?
No, air conditioning units operate independently from your existing boiler or central heating system, so brand loyalty to your heating provider has no bearing on which air con brand suits your property.
