01What a frigoría is
A frigoría is the heat you have to remove to cool a litre of water by one degree. That’s why people talk about frigorías per hour: a 3,000 frig/h unit takes out of the room, every hour, the heat that would cool three thousand litres of water by one degree.
A frigoría is a kilocalorie, only taken away rather than added.
It’s a very Spanish unit. Elsewhere in Europe it’s kW, which is why the energy label on any unit you buy is in kW even if the brochure says frigorías. British shops tend to quote kW or BTU.
02From frigorías to kW
A 2,500-frigoría split is 2.9 kW; a 3,000 one is about 3.5 kW. If the label says ‘3.5 kW’ for cooling, that’s the good old 3,000.
03And BTU
BTU is an imperial unit you see a lot in online shops. The standard round sizes on the market are these four:
| BTU/h | kW | frig/h | For |
|---|---|---|---|
| 9,000 | 2.6 | 2,270 | a bedroom |
| 12,000 | 3.5 | 3,020 | an average living room |
| 18,000 | 5.3 | 4,540 | a large living room or a small shop |
| 24,000 | 7.0 | 6,050 | a shop or a very open-plan living-dining room |
04How many each room needs
The starting figure round here is 90 frigorías per square metre. Then it goes up or down depending on the sun, the windows, whether it’s a top-floor flat and how many people there are. The result is rounded to the first catalogue unit that covers it.
| Room | m² | Sum | Unit |
|---|---|---|---|
| Small bedroom | 10 | 900 | 1,500 |
| Bedroom | 14 | 1,260 | 1,500 |
| Study | 18 | 1,620 | 2,000 |
| Living room | 25 | 2,250 | 2,500 |
| Large living room | 32 | 2,880 | 3,000 |
| Living-dining room | 40 | 3,600 | 4,500 |
Afternoon sun, single glazing or being right under the roof each add 12 to 15%: in a west-facing top-floor flat with single glazing, the 25 m² living room now needs a 3,500 unit.
To do it for your rooms, their size and which way they face, there’s the room-by-room calculator.
05SEER and SCOP: what it uses
The capacity tells you how much cooling the unit gives; the SEER tells you what it costs. A SEER of 6.1 means that, averaged over the summer, for every kWh of electricity it takes 6.1 kWh of heat out of the house. A fifteen-year-old unit was around 3: it uses twice as much for the same job.
For heating, look at the SCOP. A heat pump with a SCOP of 4 gives about 4 kWh of heat for every kWh of electricity; an electric radiator gives 1. That’s why heating in winter with the same split works out far cheaper than with heaters.
06Converter
Type in the figure you’ve got, from the box, the brochure or an online shop, and pick the unit.
Frigorías · kW · BTU
Decimals with a point.
Catalogue unit that covers it: 3,000 frig/h