Correct AC size comes from a cooling-load calculation, not a fixed "tons per square metre" rule. The right capacity depends on room area and ceiling height, glazing and orientation, insulation, occupancy, equipment heat, and — critically in Qatar — the extreme outdoor design temperature. Oversizing and undersizing both cause problems, so the goal is to match capacity to the actual load.
Why rules of thumb fail in Qatar
Generic "one ton per X square metres" guidance ignores the things that dominate the load here: 45–50°C outdoor design temperatures, large sun-facing windows, roof heat gain, and how the space is used. Two rooms of the same size can need very different capacities. That's why we calculate rather than guess.
What actually drives the size
- Area and ceiling height (volume of air to cool).
- Glazing: window size, orientation and shading — solar gain is huge in Qatar.
- Insulation: roof and wall construction.
- Occupancy and equipment: people, kitchens, IT and lighting all add heat.
- Air changes / fresh-air needs for the space type.
- Outdoor design temperature — the peak the system must handle.
Why size matters both ways
- Undersized: runs constantly, never reaches setpoint, high bills, early wear.
- Oversized: short-cycles, cools fast but doesn't dehumidify, leaving rooms cold and clammy — and wastes money on the purchase and running.
How an AGM engineer sizes your system
We carry out a room-by-room cooling-load calculation for your actual building and use, then recommend the right capacity and system type — split, ducted, or VRF for multi-room control. You get a system that cools reliably on the hottest day without wasting energy. See home & villa AC installation or talk to us about HVAC design.
Frequently asked questions
Properly, through a cooling-load calculation that accounts for area, glazing, orientation, insulation, occupancy and Qatar's extreme outdoor temperature. Rules of thumb based only on floor area are unreliable here and often lead to wrong-sized units.
No. An oversized AC short-cycles — it cools the air fast but shuts off before removing humidity, leaving the room cold and clammy, and it costs more to buy and run. Right-sizing is the goal.
It runs continuously, never quite reaches the setpoint on hot days, drives up bills, and wears out sooner. This is common when units are chosen by area alone.
Yes. We do a proper load calculation for your space and recommend the correct capacity and system type — split, ducted or VRF — so it performs on the hottest day without wasting energy.