Goodbye noise barriers: Switzerland opens the way to more densification from 2026

Why the old practice no longer worked

A key trigger for the revision was the Federal Supreme Court decision BGE 142 II 100 (“Niederlenz”) from 2016. The court made it clear at the time:

• The decisive factor is the loudest window in a noise-sensitive room – not the quietest.
• If the immission limits are exceeded there, the room is generally not permitted.
• The previous “ventilation window practice” was repealed as contrary to federal law.
• Conflicting objectives between densification and noise protection belong in the exception procedure, not in creative interpretation.

This strict legal situation meant that even well-planned densification projects were suddenly blocked. Exceeding the minimum threshold values made projects virtually impossible.

It was only a matter of time before the legislator had to intervene.

September 27, 2024: the decisive step

Parliament has set a new course with the revision of the Environmental Protection Act (EPA). The reform provides more flexibility – but it also creates clear framework conditions.

The most important changes:

1. new rules for building zones and densification

• New zoning: Compliance with planning values.
• Zoning and rezoning: IGW apply as a benchmark.
• Densification projects may exceed the PW or IGW if
  -there is an overriding interest in inner densification,
  -there is generally accessible open space,
  -structural measures ensure an appropriate quality of living.

2. two variants for the requirements per residential unit

Variant 1: with controlled domestic ventilation
– cooling system or windows with IGW compliance.

Variant 2: without controlled domestic ventilation
– IGW in at least half of all noise-sensitive rooms or an IGW-compliant room plus private outdoor space.

3. minimum protection remains mandatory
Room layout, building position and shielding must continue to be carefully planned.

What this means in practice

The revision creates real opportunities – especially in urban areas that suffer from high levels of noise pollution. At the same time, planning will become more challenging because the new requirements are heavily based on technical standards and official enforcement guidelines.

Recommendations for owners and project developers:

1. Plan noise analyses at an early stage.
   Many decisions are made in the concept phase.
2. Play through both variants.
   Ventilation systems and floor plan adaptations open up new scope.
3. Use the outdoor space strategically.
   It is becoming more relevant in terms of building law than before.
4. Justify densification properly.
   The “overriding interest” can become a decisive argument.
5. Allow for friction points.
   The interplay between the USG, LSV and building laws remains complex.

March 1, 2026: the new regulations come into force

The new requirements will be binding from this date. Projects that are being developed today must already be aligned with the future rules – otherwise there is a risk of delays, revisions or, in the worst case, rejection.