Air conditioning for your coastal home: getting the size right
An undersized unit runs flat out and never quite cools the room; an oversized one costs more and cools in bursts. This is how to work out what you need.
A quick way to size it
As a rule of thumb, allow about 100 frigories per square metre in a home with average insulation. A 12 m² bedroom needs about 1,200 frig/h and a 25 m² living room about 2,500 frig/h.
Add 15–20% if:
- The room faces south or west and gets the afternoon sun.
- It is a penthouse or top-floor flat.
- It has large windows or is open-plan with the kitchen.
- It is often used by many people at once.
Manufacturers state output in kW or frigories: 1 kW is roughly 860 frigories, so a 3.5 kW unit delivers about 3,000 frig/h.
What to look for beyond output
- Inverter: varies the compressor speed instead of switching on and off; it uses less energy and runs more quietly.
- Heat pump: the same unit heats in winter, which is very handy on the coast, where the cold is mild but damp.
- Energy rating: A++ or A+++ for cooling. You will notice it on the bill if it runs all summer.
- Noise: check the decibels of the indoor unit, especially for bedrooms.
- Multi-split: with a 2x1 or 3x1 system, one outdoor unit serves several rooms.
- Wi-Fi: switch it on before you arrive, useful for holiday homes and rentals.
Installation
Split systems use refrigerant gases and must be installed by professionals certified to handle fluorinated gases. Before fitting the outdoor unit on a façade or terrace, check with your community of owners and your local council's rules.
Split and multi-split systems from Mitsubishi Electric, Panasonic, Fujitsu, Hisense and more. See air conditioning
Updated: 2026-09-13