Air Conditioner in a Rented Apartment – What You Can and Cannot Do
Summer temperatures above 35 °C are no longer rare in German cities. For apartment renters, this raises an urgent question: can I install an air conditioner, and if so, which type — without risking my tenancy? The answer is: yes, with conditions. Here's exactly what the law says, what your landlord can and cannot refuse, and which AC solutions work best for renters.
German Tenancy Law and Air Conditioning
Split Systems (Wall-Mounted)
A permanently installed split air conditioner requires drilling through the exterior wall to run refrigerant pipes and an electrical cable to the outdoor unit. Under German tenancy law (BGB § 535ff.), this constitutes a structural modification (bauliche Maßnahme). You must obtain written consent from your landlord before proceeding.
The good news: since the Mietrechtsreformgesetz, landlords cannot arbitrarily refuse modernisation measures that improve living conditions — but they can attach conditions (bond, reversibility requirement, insurance). In practice, most landlords refuse or add costly conditions.
Mobile Air Conditioners (No Installation Required)
A portable/mobile AC unit that vents through an open window or tilted window pane requires no landlord permission. You are not modifying the property. Downsides: significantly lower efficiency (SEER 6–8 vs. 20+ for split), more noise, and the exhaust hose is aesthetically intrusive. For rooms up to 20 m², a good portable unit is a practical compromise.
Monosplit Solutions (Through-Ceiling / Micro-Duct)
Some newer systems route through existing ventilation shafts or use micro-diameter pipes with minimal drilling. These occupy a grey area — technically a modification, but less invasive. Discuss with your landlord and always get written confirmation before proceeding.
Condominium Owners (Wohneigentümer)
If you own your apartment, you still need approval from the Eigentümergemeinschaft (property owner community) if the outdoor unit will be visible from outside or mounted on shared building fabric (walls, roof, balcony). Under § 20 WEG (as reformed in 2020), you have a right to request approval for climate-improving measures — the community cannot refuse outright without good reason, but may set conditions.
Best AC Options for Renters
| Option | Landlord Permission? | Efficiency | Best For |
|---|---|---|---|
| Portable monoblock | Not needed | Low (SEER 6–8) | Renters, temporary use |
| Portable dual-hose | Not needed | Moderate (SEER 8–11) | Renters wanting better efficiency |
| Split AC (standard) | Required | High (SEER 18–24) | Owners, long-term renters with consent |
| Compact split (no outdoor unit) | Depends on model | Moderate | Apartments where balcony placement is possible |
Noise Rules for Outdoor Units
Even with landlord permission, outdoor AC units must comply with local noise regulations (TA Lärm). In residential zones (Wohngebiete), the limit is 45 dB(A) during the day and 35 dB(A) at night at the neighbour's property boundary. Most modern outdoor units from major brands operate at 48–52 dB(A) — meaning placement matters. Distance from neighbours, wall mounting vs. ground mounting, and anti-vibration pads all help stay within limits.
F-Gas Regulation and Certified Installation
Once you have landlord permission, installation of any R32 or R410A split system must be carried out by a certified F-Gas technician (EU Regulation 517/2014). This is not optional — unlicensed installation voids the manufacturer warranty and creates liability issues. R290-based systems are an exception in some EU countries but still require a qualified engineer.
Frequently Asked Questions
Can my landlord demand I remove the AC when I leave?
If you installed a split system with written landlord permission but no agreement on reversibility, you are generally obliged to restore the property to its original state when you leave (Rückbaupflicht). Always include a clause in the permission letter specifying whether the system can remain.
Is an outdoor unit on a balcony considered a structural modification?
Placing an outdoor unit on your own balcony without drilling is generally considered a non-permanent change that does not require permission — but this depends on the rental agreement and house rules. Always check your Hausordnung first.
My apartment has no balcony and my landlord refuses permission. What now?
A portable AC unit through a tilted window is your best legal option. A dual-hose unit will outperform a single-hose design and is worth the extra cost.
