How to Choose Air Conditioner Capacity for Room Area and Heat Gains

Choosing the right air conditioner capacity is not only about room area. Proper HVAC sizing also considers heat gains (теплопритоки) from people, windows, appliances, lighting, and sun exposure. If the unit is too weak, it will run constantly and still feel warm. If it is oversized, it may cool quickly but leave humidity high, causing discomfort and higher wear. Start with the base load from area. A practical rule of thumb is 100–130 W per m² (or roughly 20–25 BTU/ft²) for standard ceiling height and average insulation. Example: a 20 m² room needs about 2.0–2.6 kW of cooling (7,000–9,000 BTU/h) before adjustments. Then add heat gains: • People: add ~100–150 W per person beyond the first. • Sun and windows: add 10–30% if the room has large glazing, west/south exposure, or no shading. • Appliances: add the real power draw for electronics and cooking devices (often 200–800 W total). • Top floors/poor insulation: add 10–25% depending on roof heat and wall quality. Also check ceiling height: if above 2.7 m, increase the estimate proportionally to volume. Finally, consider usage patterns—home office with computers, a kitchen-living room, or a crowded studio will need more capacity than a bedroom. Best practice: treat rules of thumb as a starting point and confirm with a cooling-load calculation or an HVAC specialist. Correct sizing delivers stable temperature, better humidity control, quieter operation, and lower energy bills.