A permanently installed air conditioning system is a structural alteration. Whether you need a permit is decided not in the DIY store but at your municipality – and the rules differ considerably from canton to canton.
This text gives an overview to the best of our knowledge and does not replace legal advice. Your municipality is always the deciding authority, and practice differs even within a single canton. Clarify the position before you buy with the local building department – a phone call takes ten minutes and can spare you a forced removal.
The most important distinction is quickly made:
In Aargau a permanently installed air conditioning system is not in every case subject to a building permit. In residential zones a notification to the municipality is often sufficient. A full building application is required above all where the outdoor unit is to be mounted in a clearly visible position, or where the building stands in a core or conservation zone.
The cantonal guidance on cooling in residential buildings must also be observed, along with the cantonal energy regulations. One point that regularly surprises people in practice: various municipalities expect summer heat protection to be exhausted first – meaning external shading such as shutters or blinds should be in place – before active cooling is permitted. The reasoning: first make sure as little heat as possible gets in, rather than spending energy removing it afterwards.
Municipalities charge fees for processing. Depending on the procedure and the municipality, these can add up to several hundred francs.
Different accounts of the permit requirement in Aargau circulate online – from „always requires a permit“ to „a notification is enough“. This is because municipalities have considerable discretion. So do not rely on general statements, including this one, but ask your building department.
In the canton of Zurich practice tends to be stricter. An outdoor unit on a facade or a visible balcony generally requires a permit. In addition an energy compliance certificate is required, which includes demonstrating summer heat protection. In the city of Zurich and in densely built municipalities, design conditions are frequently added – for instance on the placement and screening of the outdoor unit.
Regardless of the permit procedure, the federal Noise Abatement Ordinance applies. The outdoor unit is an installation that produces sound, and the limits at neighbouring properties must be observed – particularly at night.
In practice this means the position of the outdoor unit is not simply a question of taste. A unit pointing straight at a neighbour’s bedroom window is a problem even when everything has been approved. That is why we always look at the neighbouring situation during the site visit and choose position and orientation accordingly. Where necessary, acoustic hoods, vibration decoupling or a night mode with reduced fan speed achieve a great deal.
Incidentally, a good relationship with the neighbours is the best noise protection there is: a short conversation before installation prevents more trouble than any technical measure afterwards.
If you rent, you need the written consent of your landlord before anything is fitted. A wall penetration and a unit on the facade are an intervention in the building fabric – without consent you risk, in the worst case, bearing the cost of removal and restoration.
It is best to settle at the same time what applies when you move out: does the system stay in the flat, or must it be removed? Having that in writing is better for both sides.
Similar considerations apply to condominium ownership: the facade and building envelope are usually common property, so a resolution of the owners’ association is required.
Split air conditioning systems contain refrigerants, in many cases fluorinated greenhouse gases. Work on them – charging, recovering, repairing – may only be carried out in Switzerland by people holding the relevant certificate of competence. This is not a formality: refrigerant released improperly causes considerable environmental damage and can become expensive.
During the site visit we tell you which procedure is typically to be expected in your municipality, where the outdoor unit sensibly belongs, and what to watch for regarding noise. The formal answer comes from the municipality – but you will not go there unprepared.
