Executive Summary

The Federal Department of the Interior is opening a consultation on the revision of the Federal Inventory of Worth-Preserving Local Townscapes of Switzerland (ISOS) and the Spatial Planning Ordinance (SPO). The revision aims to relax the protection of historical town centres while creating more room for new housing construction and energy transition measures. The direct applicability of ISOS will be restricted, while cantons and municipalities will receive greater discretionary scope.

Persons

  • Federal Department of the Interior (federal authority)

Topics

  • Spatial planning and monument protection
  • Housing needs and construction policy
  • Energy transition and sustainability
  • Federalism and cantonal competencies

Clarus Lead

Switzerland is modernizing its regulations for the protection of historical townscapes. The ISOS inventory, which protects town centres of national significance, is being made more flexible to enable housing construction and climate measures. Cantons and municipalities will in future have greater scope for action in applying protection regulations. The consultation period runs until 18 May 2026.

Detailed Summary

The Federal Inventory of Worth-Preserving Local Townscapes of Switzerland (ISOS) is a central instrument for preserving architectural cultural heritage. The planned revision addresses a growing conflict of objectives: while Switzerland continues to face a housing shortage and the energy transition requires massive investments in building renovation and new construction, strict ISOS regulations often restrict development opportunities.

The changes pursue three strategies: First, the previously direct applicability of ISOS is being restricted – cantons and municipalities receive greater decision-making freedom. Second, preservation objectives are being formulated more openly to create room for interpretation. Third, the discretionary scope of cantons and municipalities is being explicitly defined to increase legal certainty.

The consultation allows for statements from cantons, municipalities, interest groups and the public until 18 May 2026. Detailed documents are available via the Fedlex portal.

Key Statements

  • ISOS is being made more flexible to enable housing construction and energy transition
  • Direct applicability of the inventory is being restricted; cantons/municipalities receive greater scope
  • Preservation objectives are being formulated more openly for more pragmatic application
  • Consultation period ends 18 May 2026

Critical Questions

  1. Evidence: What empirical data shows that the previous ISOS actually represents a significant obstacle to new housing construction? Are there case studies of denied projects?

  2. Conflicts of interest: Which interest groups (real estate industry, monument preservation, environmental associations) have influenced the revision, and how is their independence ensured?

  3. Causality: Does greater discretionary scope actually lead to faster housing construction, or do new conflicts arise between cantons and the federal government? What alternatives (e.g. exemption regulations instead of general liberalization) were considered?

  4. Feasibility: How will cantons and municipalities be supported in redefining preservation objectives? Is there a risk of erosion of monument protection through different interpretations?

Source Index

Primary source: Consultation opening: Amendment ISOS and SPO – Federal Department of the Interior, 11 February 2026

Verification status: ✓ 11 February 2026

This text was created with the support of an AI model. Editorial responsibility: clarus.news | Fact-checking: 11 February 2026