State of research

Investigations into the fire behaviour of green facades have been carried out in particular by the Municipal Department 39 of the City of Vienna in conjunction with the University of Natural Resources and Applied Life Sciences Vienna. Until 2014, hardly any in-depth investigations on the fire load potential of greened façades had been carried out in Europe and even today only a very small number of findings are available.

The studies known to date are presented below in chronological order:

•     2013; Department for Communities and Local Government in London; Five fire tests on manufacturer-specific green wall systems, study "Fire Performance of Green roofs and Walls".
•     2016-2017; University of Natural Resources and Applied Life Sciences, Vienna; Fire tests in a muffle kiln as part of bachelor theses to determine the flammability and fire behaviour of climbing plants.
•     2015-2018; Municipal Department 39 City of Vienna; Four large-scale fire tests following ÖNORM B 3800-5 with facade greenery at different distances from the fire chamber.
•     2019; Technical University Munich; Four large-scale fire tests within the scope of a master thesis with creeping spindle, blue vine, wild vine, kiwi, perennials and herbs
•     2020; Magistratsabteilung 39 Stadt Wien; Seven large-scale fire tests in accordance with ÖNORM B 3800-5 with façade greening at different distances from the façade and with fire barriers.

Classification of façade greening systems according to building regulations

As an example, reference is made within this text to the Bavarian Building Code (BayBO) and its commentary. The other 15 state-specific building regulations contain analogous explanations. The BayBO as a law, according to its scope of application under Art. 1, is valid for "structural installations and building products. It also applies to land as well as to other installations and facilities for which requirements are imposed according to this law or in regulations based on this law."

According to Art. 2 (1) sentence 1 BayBO, structural installations are installations connected to the ground and made of construction products.

Building products are products that are manufactured, i.e. artificial results of human activity. Furthermore, the purpose of manufacture and use of construction products is their incorporation into structural installations or their use as structural installations [6]. According to Art. 2 (11) BayBO, construction products are products, building materials, components, installations and kits that are manufactured to be permanently installed in building structures or prefabricated installations made of them that are manufactured to be connected to the ground.

The scope of application of the BayBO also includes the property itself as well as other installations and facilities that are subject to requirements under the Building Code or in regulations based on the Building Code. Other installations and facilities are those that do not fall under the concept of structural installations and building products. Other installations in this sense are e.g. trees (Art. 7 para. 1 sentence 1 No. 2, Art. 81 para. 1 No. 7) or hedges as enclosures (Art. 57 para. 1 No. 7).

Taking into account the scope of application of the Building Code, it can be stated that fastening systems and climbing aids of façade greenery fall within the scope of application as building products. However, the vegetation of the façade greening, as a non-artificially produced product, can at most be rated as other plant and equipment. However, a clear building code requirement for façade greening cannot currently be found within the building code, except for the general requirements for exterior wall cladding according to Art. 26 Para. 3. It is questionable whether the requirements for exterior wall cladding are also valid for façade greening itself. It would be very desirable for the representatives of the building supervisory authorities to agree on a final classification for further consideration.