ISOS as a basic instrument
The Federal Inventory of Swiss Sites of National Importance, better known as ISOS, is a basic instrument that helps the authorities to recognise architectural values and safeguard them in the long term. Cantons and municipalities take the inventory into account when drawing up their corresponding plans (structure planning, utilisation planning). The ISOS was created in the 1970s and comprises around 1,200 objects.
Binding nature of the ISOS for property owners
If a property is located in an area covered by the ISOS, this does not mean much, as the ISOS is generally not binding for landowners. However, the municipalities are obliged to take the ISOS into account in land-use planning as part of the comprehensive weighing up of interests under spatial planning law. The building project must be compatible with the applicable land-use planning and comply with the specific requirements of the zone (e.g. a village or core zone). Only where the municipal council, as the building permit authority, has discretionary powers when assessing your planning application must it directly take into account the conservation objectives of the ISOS.
Direct applicability due to federal tasks
If the building project affects a federal task, the listed property must be preserved undiminished, or at least protected as far as possible (Art. 6 NHG). However, this only applies in the case of serious encroachment on the ISOS object. According to case law, serious encroachment exists if a construction project causes extensive and irreversible damage. In such a case, an expert opinion must be obtained from the Swiss Federal Commission for the Protection of Nature and Cultural Heritage (ENHK) and / or the Swiss Federal Commission for Monument Preservation (EKD). Planning permission may only be granted if the building project is of national importance. The national nature and heritage conservation organisations are then entitled to appeal against the building project.
Typical cases of application
Federal tasks are affected if the building permit relates to a legal matter that falls under federal jurisdiction, is regulated by federal law and is related to nature, landscape and cultural heritage protection. In practice, frequent cases that fall under a federal task according to federal court rulings are when a PV system (Art. 18a RPG) or a mobile phone system (Art. 14 FMG) is authorised or a permit is required under water protection law (Art. 19 para. 2 GSchG).
To summarise, although the ISOS is not directly applicable to landowners, there are practical exceptions that can often lead to the direct applicability of the ISOS. In this case, further complicated clarifications may be necessary for the construction project, which gives third parties leverage to delay a project.
