HVAC · 4 min read · 2026-10-05
How to size an air conditioner for a Nairobi office
A simple method to estimate cooling load in BTU/h and why oversizing wastes money.
Air conditioners are sold in BTU/h: 9,000, 12,000, 18,000, 24,000 and so on. Too small and the room never cools; too large and the unit short-cycles, wastes energy and leaves the air damp.
A quick estimate
Start with floor area. Nairobi's mild climate means a typical office needs roughly 450 to 600 BTU/h per square metre. Add about 600 BTU/h for each person beyond two, and about 3.4 BTU/h for every watt of computers and equipment. Rooms with large west-facing glazing need more.
Worked example
A 30 m² office with five people and 1,000 W of equipment: 30 × 500 = 15,000, plus 3 × 600 = 1,800, plus 3,400 for equipment, gives about 20,200 BTU/h. A 24,000 BTU/h unit would be the practical choice.
Before you buy
- Get a site survey: orientation, glazing and ceiling void matter.
- Plan condensate drainage before installation.
- Inverter units cost more but save energy at part load.
- Budget for servicing every three to six months.
Our cooling load estimator in the AI tools section runs this calculation for you.