Can Your Landlord Ban a Portable AC? What Tenants Are Still Allowed to Do

With portable AC units, landlords have far less say than most tenants assume. Here is where your rights end and when consent actually becomes mandatory.

5 min read · Updated July 2026

It is 34 degrees outside, your flat has been trapping the heat since noon, and your landlord says: "Air conditioning? Out of the question." The good news: with a portable AC unit, that "no" is often not his to make. A permanently installed system is a different matter. Below is what the law in Germany actually says and how to handle it without a fight.

A portable AC unit is usually not the landlord's to forbid

Legally, a mobile monoblock unit is a movable household appliance, in the same category as a fan, a fan heater or a tumble dryer. You set it down, the warm exhaust hose runs out through a tilted window, and that is it. Because you change nothing about the building fabric, this falls under the ordinary, contract-compliant use of your flat, which your landlord cannot simply prohibit across the board.

• No drilling, no holes, no fixed mounting: the unit stays movable.
• The exhaust hose runs through a tilted window, often with a fabric window seal that leaves no marks.
• A clause in the lease banning "any air conditioning" generally does not hold up against a free-standing monoblock unit.

When the landlord genuinely can say no

Your freedom is not unlimited. Once a movable appliance turns into a structural intervention, or neighbours are disturbed, the landlord can step in with good reason.

• Structural change: holes in the wall or window frame, a permanently fixed outdoor unit or a wall breakthrough all need his consent.
• Facade and appearance: parts that visibly stick out of the window or across the facade can be restricted on aesthetic grounds.
• Noise: if the unit runs at night and drones into the neighbour's flat, quiet hours and the house rules apply.
• Damage: you are liable for condensation, moisture or an overloaded electrical circuit.

Fixed split systems: consent and a certified installer are mandatory

A classic split air conditioner with an indoor unit and a permanently mounted outdoor unit is a different story. That counts as a structural change, and nothing happens without the landlord's written consent. On top of that, because of the refrigerant, such a system may only be installed by a certified specialist firm (the keywords are the F-Gas Regulation and proof of competence). Without permission you risk a formal warning, removal at your own cost and an argument about the marks left behind. Note the distinction: this applies to fixed systems with a drilled-in outdoor unit. Mobile split units whose refrigerant circuit is permanently sealed at the factory and that need no fixed mounting count as permission-free, just like a monoblock.

What to do when the landlord pushes back

• Ask for the specific reason. If it is about drilling and the facade, that often has nothing to do with your mobile unit.
• Point out calmly that a free-standing monoblock unit is not a structural change.
• Put any agreement in writing, for example by email.
• For fixed systems: get written consent up front and plan in a certified installer.
• If it stays contentious, your local tenants' association (Mieterverein) or a short legal opinion will help.

The bottom line: your landlord can rarely forbid a portable AC unit as long as you rebuild nothing, disturb no one and leave no damage. If you want a fixed installation instead, there is no way around his consent and a certified firm. When in doubt, a quick trip to the tenants' association is worth it before the summer is over.

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