How to Keep Your Home Comfortable With the Right AC

Summers are getting hotter, and more of us are working from home through them. A good air conditioner has gone from luxury to something close to essential — but the market is confusing, and the wrong choice is loud, expensive to run and still leaves you sweating.

First, pick the right type

Portable units sit on the floor and vent hot air through a hose in the window. They’re cheap and need no installation, but they’re the noisiest and least efficient option. Choose a dual-hose model if you can; single-hose units pull warm air in from the rest of the house.

Window units sit in the frame. They’re efficient for the money and quieter than portables, but not every window suits them and they block the view.

Split systems put the noisy compressor outside and a slim unit on your wall. They’re the quietest and most efficient by a distance, and most double as a heat pump for winter. The catch: professional installation and a higher upfront cost.

Size it to the room

An undersized unit runs flat out and never gets there; an oversized one cools too quickly, switches off, and leaves the air clammy. As a rough rule, work from floor area:

Room size	Approximate capacity
Up to 15 m²	7,000 BTU / 2 kW
15–25 m²	9,000 BTU / 2.6 kW
25–35 m²	12,000 BTU / 3.5 kW
35–50 m²	18,000 BTU / 5 kW

Add capacity for south-facing rooms, top-floor flats, kitchens and rooms with a lot of glass.

Read the specs that matter

• Noise (dB): under 45 dB indoors is comfortable for a bedroom; many portables run at 55–65.
• Efficiency rating: a higher SEER figure means lower running costs over the unit’s life.
• Inverter compressor: modulates its speed instead of switching on and off — quieter, steadier and cheaper to run.
• Dehumidifier mode: useful on muggy days when temperature isn’t the real problem.

Placement and habits

Keep the unit out of direct sun and away from heat sources like ovens and TVs. Close curtains on sun-facing windows during the day. Set the thermostat to a sensible 24–25°C rather than 18°C; the room won’t cool faster, it’ll just cost more. Clean or replace filters every few weeks in summer.

The verdict

If you own your home and plan to stay, a split system is the best long-term buy. Renters and occasional users are best served by a dual-hose portable with an inverter. Whatever you choose, pair it with the draught-proofing in our pre-winter repairs checklist — a well-sealed house is easier to keep cool as well as warm.