United Kingdom
Portable and split air conditioners carry energy labels. Mild summers may make fans and shading adequate for many homes.
More on UKBuying guide
Draft / Under researchCooler homes, considered choices.
Air conditioning, fans and evaporative coolers all have trade-offs involving electricity, water, refrigerants, climate and comfort. The most suitable option depends on where you live, how your home is built and what impacts matter most to you.
Last reviewed · Concept draft, not yet independently reviewed
Why it matters
Cooling is a large share of household energy use in hot climates, and it is growing. Choices about shading, insulation and equipment can change both comfort and environmental impact.
Fans vs evaporative coolers vs AC
Fans move air and use little electricity but do not lower air temperature. Evaporative coolers lower temperature by evaporating water, working well in dry climates and poorly in humid ones. Air conditioners remove heat and humidity using refrigerant and are effective in most climates at higher energy cost.
- Fans: lowest energy use; best when temperatures are moderate.
- Evaporative coolers: low electricity, uses water, best in dry heat.
- Air conditioning (including heat-pump systems): works in humid heat, highest electricity demand, involves refrigerants.
Energy efficiency
Look for seasonal efficiency ratings in your market. Inverter (variable-speed) units generally use less energy than fixed-speed ones when properly sized. Oversized units cycle on and off, which wastes energy and controls humidity poorly.
Water use
Evaporative coolers consume water continuously. In water-scarce regions this is a significant factor; in some regions water restrictions may apply. Check local conditions.
Refrigerant leakage and climate impact
Air conditioners use refrigerants, some of which have a high global warming potential if released. Installation quality and end-of-life handling matter. Ask the installer which refrigerant is used and how leaks are prevented.
Repairability
Sealed refrigerant circuits require qualified technicians. Check that servicing is available locally and for how long, and avoid products with no clear spare-parts support.
Climate-specific advice
Hot and dry: shading, ventilation and evaporative cooling may be effective. Hot and humid: dehumidification is the main issue, and AC is often the practical option. Cold-winter regions: a heat-pump system can provide both heating and cooling, with efficiency that depends on the model and climate.
Decision checklist
- Can shading, insulation or ventilation reduce the need?
- Which cooling type suits my climate and home?
- What is the rated efficiency, and how large a room does it serve?
- Which refrigerant does it use, and who will service it?
- What is my water situation if I choose evaporative cooling?
What to look for
- Capacity matched to room size.
- Seasonal efficiency rating in your market's units.
- Refrigerant type and global warming potential, if disclosed.
- Water consumption for evaporative units.
- Servicing and spare parts.
Common unknowns
These are things that are often not disclosed. Record them as not verified, never as safe.
- Real-world energy use in your home and habits.
- Refrigerant leakage over the lifetime of the product.
- Materials in filters, pads and plastic housings.
Questions to ask
- What is the seasonal efficiency of this model under my country's test standard?
- Which refrigerant does it contain, and what is the charge?
- What routine maintenance is needed and who can perform it?
- For evaporative units, how many litres of water does it use per hour?
Comparison criteria
- Cooling capacity and room size
- Rated efficiency
- Annual running cost estimate
- Water use (if applicable)
- Refrigerant type and charge
- Noise and repairability
Country differences
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United States
ENERGY STAR and SEER-type ratings apply to many cooling products. Regional climate matters considerably, from humid southeast to dry southwest.
More on USACanada
Heat pumps can provide both heating and cooling; look at cold-climate performance data for your region.
More on CanadaAustralia
Star-rating labels and climate-zone data help compare reverse-cycle units. Evaporative cooling is common in dry regions, with water use to consider.
More on AustraliaWhat we know
- Cooling type should be matched to climate: evaporative works in dry heat, AC in humid heat.
- Oversized air conditioners are less efficient in practice.
What remains unclear
- Lifetime refrigerant leakage varies widely with installation quality.
- Real-world energy use depends heavily on behaviour and building design.
Sources and references
External links are research leads, not endorsements. Check the current page, publication date and scope before relying on them.
Last reviewed . Spotted an error or have newer evidence? Tell us.