AC and neighbour law in Germany: noise limits, condensate, and how to avoid disputes

How loud your AC may legally be, where the condensate is allowed to go, and how to keep the peace with the people next door.

6 min read · Updated July 2026

A monoblock humming on the bedroom floor, a window unit sitting on the balcony, and suddenly there's a knock at the door. Portable AC is legal in Germany, but few summer appliances land people in front of the local court as often. Almost every dispute comes down to two things: noise and water. Both are easy to get right once you know the rules, and much cheaper to sort out before your neighbour does it for you.

Noise: what counts is measured at your neighbour's window, not at the unit

German courts don't ask how loud the device is on the box. They ask how much noise arrives at the affected home, measured roughly half a metre outside the neighbour's window. As orientation, judges lean on the immission values from the TA Lärm (the technical guidance on noise protection). The limit depends on the type of area you live in and, above all, on the time of day. Night, from 22:00 to 06:00, is where most complaints are won.

• Purely residential area (reines Wohngebiet): about 50 dB(A) by day, 35 dB(A) at night
• General residential area (allgemeines Wohngebiet): about 55 dB(A) by day, 40 dB(A) at night
• Mixed area (Mischgebiet): about 60 dB(A) by day, 45 dB(A) at night
• Night runs 22:00 to 06:00; on Sundays and public holidays many house rules treat the whole day as quiet time

For context, 35 dB(A) is very quiet, close to a library. Many portable monoblocks run louder than that at the unit, which is why placement and a night mode matter so much (more on that below). If the noise stays clearly below the night value at the neighbour's window, you're on solid ground. If it doesn't, they can ask you to turn it down at night under §§ 906 and 1004 of the German Civil Code.

Condensate: not a single drop onto someone else's property

Water is the second flashpoint, and here the rule is stricter than for noise. You may not let condensate or drain water run onto a neighbour's balcony, wall, or land. A neighbour has to tolerate minor, unavoidable effects like a faint hum, but water dripping down from your unit onto their space is a direct intrusion they can simply refuse. It's a classic §1004 removal claim.

• Catch the condensate from window units and split-style boxes; don't let the drip line fall onto the balcony below
• Empty or plumb in a portable monoblock's condensate tank instead of tipping water over the railing
• Route any drain hose into your own gully, floor drain, or a sealed container, not toward the boundary
• Check the run after heavy, humid days, when units produce the most water

This is also a self-interest thing. Water that pools on a balcony or seeps into masonry causes damage you can be held liable for, long before your neighbour gets annoyed about the stain.

Placement and night mode: quiet by design, not by luck

Most noise complaints are really placement complaints. A unit pointed straight at the neighbour's open bedroom window at midnight will cause trouble even if it's a quiet model. A few habits remove almost all of the friction:

• Aim the exhaust and the loud side away from neighbouring windows and balconies, not toward them
• Use the quiet or night mode after 22:00; the lower fan speed usually buys you several decibels
• Stand the unit on rubber feet or a mat so vibration doesn't travel through the floor into the flat below
• Keep windows on your side reasonably closed with a window seal, which also stops the noise leaking out

One quiet conversation before the first hot night is worth more than any legal argument. Telling the neighbour you've set it to night mode and pointed it away from their bedroom usually ends the matter before it starts.

Renting: permission-free or landlord consent?

As a tenant you can generally use a mobile monoblock without asking the landlord, because setting up a plug-in appliance isn't a structural change (bauliche Veränderung). What you still owe is respect for the house rules and the quiet hours. The moment installation becomes permanent, the picture changes.

• Mobile monoblock, freestanding: usually permission-free; just mind noise, condensate, and the Hausordnung
• Window unit with brackets, or anything drilled or screwed into the building: needs the landlord's consent
• Fixed split system with an outdoor unit and a wall penetration: needs landlord consent and, as a rule, a permit plus a certified firm
• Refrigerant handling: fixed splits fall under F-Gas rules and must be installed by a certified technician; sealed mobile units don't

The reason sealed devices are simpler is that their refrigerant circuit is closed at the factory. Mobile monoblocks, window units, and permanently sealed mobile splits arrive pre-charged and hermetically sealed, so no one opens the circuit and no F-Gas certificate is required. Classic fixed splits are the opposite: the circuit is joined on site, which is exactly why they need a certified installer and, usually, a permit. Permission-free, sealed units are the category KlimaLegal focuses on, precisely because they sidestep most of this.

How to stay out of court

If a neighbour does complain, the law expects you to reduce a genuine, significant nuisance, not to switch the thing off forever. Turn on night mode, move or angle the unit, fix any dripping water, and put it in writing that you've done so. Most disputes end there. The ones that escalate are almost always the ones where someone ignored a reasonable request for weeks.

Keep it simple: run it quietly at night, make sure not a drop lands on anyone else's property, and say a word to your neighbour before the first heatwave. Do those three things and a portable AC is one of the least contentious ways to get through a German summer.

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