How to Size an AC for a Room in Accra
Why the Wrong Size Costs You Twice
The single most common AC mistake we see in Accra is a unit that was never sized for the room. It happens both ways. Buy too small and the unit runs flat-out all day and never quite cools — high bill, no comfort. Buy too big and it cools the air fast, switches off, and switches back on minutes later, never running long enough to pull the humidity out. You end up with a room that is cold and clammy, a compressor that wears from constant cycling, and a bill higher than it should be.
Solar AC Ghana installs and services AC across Accra by EC-certified technicians, since 1989. Sizing is the part most people get wrong before we are even called — so here is how it actually works.
The Starting Point: Room Area
AC capacity is rated in BTU (or in horsepower locally — roughly 1HP ≈ 9,000 BTU). The first input is floor area. As a rough, honest starting guide for a standard residential room:
| Room size | Indicative capacity |
|---|---|
| ”Small bedroom (up to ~14 m²)" | "~1HP / 9,000 BTU" |
| "Standard bedroom / small living room (~14–20 m²)" | "~1.5HP / 12,000 BTU" |
| "Large living room (~20–30 m²)" | "~2HP / 18,000 BTU" |
| "Open-plan / large space (~30 m²+)" | "Surveyed multi-split or larger” |
These are starting points, not answers. Floor area is only the first of several inputs — which is exactly why a phone quote off room size alone tends to miss.
What Else Changes the Number — Accra Specifics
The textbook BTU-per-square-metre tables are written for temperate climates. Accra is not temperate, and several local factors push the real figure up.
Sun Exposure and West-Facing Walls
A room that takes the afternoon sun on a west or north-west wall gains a lot of heat. A bedroom under an uninsulated roof slab gains more again. These rooms need more capacity than floor area alone suggests.
Ceiling Height and Glazing
High ceilings mean more air volume to cool. Large or unshaded windows are heat gains in their own right — a glass-fronted living room behaves very differently from a small shuttered bedroom of the same floor area.
Occupancy and Heat-Producing Equipment
People give off heat, and so does equipment. A bedroom for one sleeper is a lighter load than a home office with two people, a desktop, and a fridge. A kitchen-adjacent open plan is heavier again.
Humidity — The Quiet One
Accra’s humidity is the factor most undersizing ignores. An oversized unit cools the air temperature fast and shuts off before it has dehumidified — leaving the room cold and damp. Correct sizing keeps the unit running long enough to actually pull moisture out, which is half of what comfort means here.
Bigger Is Not Better
It is worth saying plainly, because the instinct is to “round up to be safe”: an oversized AC is a real problem, not a safe margin. It short-cycles — cools fast, cuts out, restarts minutes later. That cycling wears the compressor, wastes power on every restart surge, and never dehumidifies properly. The right size runs steadily and long enough to do both jobs: drop the temperature and dry the air.
Inverter vs Fixed-Speed
A fixed-speed unit is either full-on or off. An inverter unit modulates its compressor to hold the temperature, which means it runs gently and continuously rather than slamming on and off. For Accra’s heat and humidity, an inverter unit is usually the better choice — steadier comfort, lower running cost, and a far better partner if you ever run it on solar. All current units use R-410A or R-32 refrigerant; R-22 is phased out.
How We Actually Size It On Site
We do not quote AC capacity off a phone call describing a room. On the survey we measure the floor area and ceiling height, check the wall orientation and sun exposure, look at the glazing and roof, and ask how the room is used and by how many people. Only then do we specify the unit — and the price is confirmed from that survey, before any work.
The Takeaway
Room area gives you a starting BTU figure. Sun, ceiling, glazing, occupancy, and Accra’s humidity all move it. Too small never cools; too big leaves you cold and damp. The right size, installed properly, runs steadily and quietly — and costs less to run for it.
Solar AC Ghana sizes and installs AC right the first time, across Accra since 1989. Call +233 23 063 0026 — we survey the room and size the unit to it.
Related Services
- AC Installation — new splits and multi-units, sized and fitted right
- AC Servicing — same-day when a unit stops cooling
- Solar Installation — cut the bill your AC drives up
- Solar + AC Combined — run your cooling on the sun