Which Air Conditioners Are Effectively Off-Limits for Renters in Germany

Fixed split systems, wall penetrations and F-gas work aren't outright "illegal" for tenants, but three rules make them nearly impossible to install on your own. Here's what actually stops you, and what you're free to use instead.

6 min read · Updated July 2026

No German law says a tenant may never have air conditioning. But there's a difference between what's technically for sale and what you're actually allowed to install in a flat you don't own. Three things quietly rule out most "real" air conditioners for renters: the wall penetration a fixed system needs, the refrigerant inside it, and your landlord's right to say no. Once you understand those three, the whole topic gets a lot simpler.

The short version: what's forbidden vs. permission-free

It helps to split every AC into two buckets before you look at prices or specs.

• Effectively off-limits without permission: fixed split systems with an outdoor unit, anything that requires drilling through an exterior wall, and any device where a technician has to open the refrigerant circuit on site.
• Permission-free for tenants: mobile monoblock units (single hose out of a tilted window), window units, and permanently sealed "mobile split" devices that come pre-filled and need no refrigerant work.

No single statute bans that first bucket. What blocks it is the combination of tenancy law, the EU F-gas rules and, in many buildings, condominium or heritage rules on top of that.

Fixed split systems: the wall is the real problem

A classic split system has an indoor unit and an outdoor unit connected by refrigerant lines. To run those lines you drill through the building's exterior wall and mount a compressor on the facade. For a tenant that's the sticking point, because drilling through the shell and fixing hardware to the outside counts as a structural change to the rented property (a bauliche Veränderung).

Structural changes need your landlord's consent. Get it in writing before anything is drilled. Without consent the landlord can demand you remove the unit and restore the wall to its original state (Rückbau) at your own cost, and can hold back your deposit to cover it. "I'll just take it down when I move out" doesn't protect you if the facade or masonry is left damaged.

F-gases: why you legally can't do the refrigerant work yourself

Split systems run on fluorinated greenhouse gases (F-gases). Under the EU F-gas Regulation, connecting, filling or servicing a refrigerant circuit that contains these gases may only be done by certified personnel who hold a proof of competence (Sachkundenachweis). A tenant filling or opening the circuit personally isn't allowed, and a botched job also risks leaks and voided warranties.

That's the quiet reason a fixed split is never a weekend DIY project: even if your landlord agreed to the wall, the installation still has to go through a certified firm. Mobile monoblock and sealed mobile-split units sidestep this entirely, because they leave the factory as a closed, pre-charged system that no one opens on site.

What renters can install without asking anyone

The permission-free category exists precisely because it touches neither the building shell nor the refrigerant circuit.

• Mobile monoblocks: a free-standing unit that vents warm air through a single hose, usually via a window seal. No drilling, no outdoor unit, no F-gas handling.
• Window units: mounted in the window opening itself, no permanent penetration of the wall.
• Sealed "mobile split" devices: pre-filled at the factory with a closed circuit, so there's no on-site F-gas work and no facade mounting.

None of these need a building permit or, as a rule, formal landlord approval, since you're not altering the substance of the flat. This is the lane seasonal rental services like KlimaLegal deliberately stay in: cooling you can use and later remove without touching the walls. Common courtesy still applies. Don't run a noisy unit onto a shared courtyard at night, and check your lease for any clause about window fittings.

Special cases that can tighten the rules further

Even a permission-free device can run into a few extra layers, and a fixed split almost always does.

• Condominium buildings (WEG): the facade is usually shared property, so an outdoor unit needs a resolution from the owners' association, not just your landlord's nod.
• Heritage protection (Denkmalschutz): on listed buildings, visible units on the facade are frequently refused outright.
• Noise (TA Lärm and local rules): an outdoor compressor must not exceed noise limits at the neighbour's window, which can rule out a spot even if everyone else agrees.

Before you buy anything, confirm three things in this order: is it permission-free, does it need to touch an exterior wall, and does anyone besides your landlord (owners' association, heritage office) have a say. If the answer to the first is yes, the other two usually fall away, and that's the fastest, lowest-risk route to a cool flat as a tenant. If you have your heart set on a fixed split, treat it from day one as a project that needs written landlord consent and a certified installer, never a purchase you sort out afterwards.

Read next