Looking for air conditioning for your apartment without drilling walls? This guide compares all available options for 2026.
Mobile AC or Air Cooler — What Works in an Apartment?
For apartments where wall penetration is not allowed, portable air conditioners are the most practical solution. Unlike split units, they require no external installation — the exhaust hose is simply routed through a tilted window.
| Criterion | Mobile AC | Split AC | Air Cooler |
|---|---|---|---|
| Installation | None (plug & play) | Technician required | None |
| Cooling power | 7,000–18,000 BTU | 9,000–24,000 BTU | Refreshing, no actual cooling |
| Noise level | 45–55 dB | 19–28 dB (indoor unit) | 35–50 dB |
| Energy class | A to A+ | A++ to A+++ | A+++ |
| Price | €299–€899 | €800–€2,500 | €89–€299 |
How Many BTU Do I Need? — Quick Calculator
Base formula: room area (m²) × 100 BTU. Correction factors:
- South-facing / top floor: × 1.25
- Poor insulation: × 1.15
- More than 3 people in the room: + 600 BTU per person
| Room size | Recommended BTU |
|---|---|
| Up to 15 m² | 7,000 BTU |
| 15–25 m² | 9,000–10,000 BTU |
| 25–35 m² | 12,000 BTU |
| 35–50 m² | 14,000–18,000 BTU |
Single Hose or Dual Hose?
Single hose: simplest setup, suitable for occasional use up to 25 m².
Dual hose: up to 20% more efficient, ideal for continuous use or larger rooms.
Frequently Asked Questions
Do I need permission for a portable AC in a rental?
No. Portable air conditioners require no structural changes and therefore no landlord or HOA permission. The exhaust hose is routed through a tilted window or a window sealing kit.
How loud is a portable air conditioner really?
Most modern units operate at 45–52 dB in normal mode — comparable to a running refrigerator. For bedrooms, we recommend models below 48 dB on the lowest fan setting.
Can I use the air conditioner as a heater in winter?
Many portable air conditioners include a heat mode (heat pump). At outdoor temperatures above –5°C, operation is typically efficient (COP 2–3).