Indicative investment: about €55/m² of facade area (ETICS system)
Eko sklad subsidy: up to 40 % of eligible costs, capped at €35/m²
Effect: transmission losses through walls reduced by 60-70 %
Insulation thickness
In Slovenia, 15-20 cm of expanded polystyrene or mineral wool has become the economic optimum. The price difference between 10 and 16 centimetres is relatively small, because most of the cost lies in labour, scaffolding and finishing layers rather than in the insulation material itself. Economising on thickness therefore almost never pays off - you will not be adding to the insulation later.
Workmanship matters more than material
An ETICS system involves substrate preparation, bonding and mechanical fixing of the boards, a reinforcing mesh in the adhesive layer, and the final render. The critical points are the correct treatment of thermal bridges - reveals, balcony slabs, roof junctions and the plinth - and appropriate vapour permeability of the build-up. A poorly executed facade can cause condensation within the construction and lead to mould, which costs far more than any saving on the contractor.
Combine with other work
It makes sense to renovate the facade together with replacing the windows, as this is the only way to correctly integrate the window frames into the insulation layer. If the windows are replaced later, the facade reveals have to be opened up again.