The disclosure relates to façade system for a building, in particular an External Thermal Insulation Composite System (ETICS), comprising a thermal and/or acoustic insulation, consisting of at least one insulation element being a bonded mineral fibre product made of mineral fibres, preferably stone wool fibres, and a cured aqueous binder composition, whereby the insulation element is fixed to an outer surface of the building by mechanical fastening elements and/or an adhesive, covered with a rendering, and whereby the aqueous binder composition prior to curing comprises a component (i) in form of one or more oxidized lignins, a component (ii) in form of one or more cross-linkers, a component (iii) in form of one or more plasticizers, and whereby the insulation element has a bulk density between 70 kg/m3 and 150 kg/m3.