How to Choose an Air Conditioner by Room Area and Heat Gains (Apartment / Office / Shop) in Los Angeles

Choosing the right air conditioner is not only about square footage. In Los Angeles, real cooling demand depends on heat gains: sun exposure, insulation, people, lighting, and equipment. A quick starting point is sizing by area. For average conditions, plan about 20–30 BTU per sq ft (roughly 200–300 BTU per m²). Example: a 300 sq ft room often needs around 6,000–9,000 BTU/h, while 500 sq ft may require 10,000–15,000 BTU/h. This rule works best for typical apartments with standard ceiling heights. Then adjust for heat gains. Add capacity if the room has large south/west-facing windows, intense afternoon sun, poor insulation, or top-floor exposure. Offices and retail spaces usually need more because of internal loads: computers, display lighting, refrigeration, and steady foot traffic. A common practical step is to add 10–20% for strong sunlight, and another 10–30% for high occupancy or equipment-heavy rooms. Ceiling height also matters: high ceilings increase the air volume to cool. Match the AC type to the space. Apartments often benefit from a quiet wall-mounted mini-split for one zone, or a multi-zone system for several rooms. Offices may need zoning and consistent airflow, making ducted systems or multiple splits a better fit. Shops typically prioritize even coverage and the ability to handle door openings, so consider higher capacity and better air distribution. For best results, confirm sizing with a professional load calculation (Manual J or equivalent) listed in your HVAC business directory. Proper sizing improves comfort, lowers energy bills, and reduces humidity issues caused by oversized units short-cycling.