Facts

The appellants, [A.] (owner of parcels nos. 159 and 160 in the Commune of Vullierens, in an agricultural zone, with quality I crop rotation area) and [B.] (farm operator, tenant of part of parcel no. 159 for ten years, from 1 January 2018 to 31 December 2028), request a building permit for a multi-tunnel chapel greenhouse of 4'665 m² intended for strawberry cultivation, as well as a wastewater pit.

The planned greenhouse would be moved from parcel no. 501 in Cossonay (village of Allens), owned by a third party. Parcel no. 159 already supports an agricultural greenhouse of 4'427 m². The total greenhouse area on this parcel would thus reach 9'092 m².

The project was published for public inspection from 16 May to 14 June 2018 without objection. In the CAMAC summary of 30 July 2018, the Territorial Development Department (SDT, now the Directorate-General for Territory and Housing) refused the special authorisation for the greenhouse, on the ground that the total area exceeded the admissible internal development within the meaning of arts. 16a SPA and 34 para. 1 and 37 SPO, and that the project had to be located in a specialised agricultural zone within the meaning of art. 52a LATC. The pit, however, was authorised.

The Court of Administrative and Public Law of the Vaud Cantonal Tribunal (CDAP) dismissed the appeal by judgment of 31 October 2019 (AC.2018.0290). The appellants lodge a public law appeal with the Federal Supreme Court, seeking the grant of the special authorisation or an order to the municipality to issue the permit, and in the alternative the remittal of the case. The SDT requests dismissal. The Federal Office for Spatial Development (ARE) notes that, although the cantonal reasoning cannot be followed, the siting should be examined and a weighing of interests carried out within the meaning of art. 34 para. 4 let. b SPO.

Main question: must the area of existing greenhouses on the same parcel be taken into account in calculating the 5'000 m² limit of art. 37 para. 1 SPO, when the new greenhouse would serve a separate agricultural holding?

Considerations

On admissibility, the Federal Supreme Court holds that the appeal is directed against a final decision (art. 90 FSCA) rendered as the last cantonal instance (art. 86 para. 1 let. d FSCA) in the field of public construction law (art. 82 let. a FSCA). The appellants, owner and future tenant-operator, have standing within the meaning of art. 89 para. 1 FSCA.

On the merits, the appellants argue that art. 37 SPO only concerns the internal development of an operation, so that only the area of the planned greenhouse would count. The Federal Supreme Court recalls the principles of interpretation (literal, historical, teleological and systematic interpretation, pragmatic pluralism). The text of art. 37 SPO does not directly answer the question; other methods of interpretation must therefore be used.

The Federal Supreme Court notes that art. 16a SPA, art. 34 SPO and case law (BGE 129 II 413) govern internal development. During the partial revision of 2007, the absolute limit of 5'000 m² was maintained despite the proposal to remove it, precisely to avoid internal developments of a scale incompatible with the legislature's intent. This limit aims to prevent uncoordinated development from multiplying constructions on the same land, to the detriment of the agricultural zone, which must remain as far as possible free of construction.

The Federal Supreme Court confirms that an overall assessment of the project must be carried out, taking into account constructions already erected on the land, even where the holdings are distinct. Greenhouses forming a unit from the territorial, landscape and soil-impact perspectives must be considered together. The fact that leasing part of the land would allow the rules to be circumvented is not admissible. The cantonal court therefore did…