24 · CHAPTER 24 · BUILDING PHYSICS Chapter 24 · Building physics
Building-physics classification & limits
Nanofassadendämmung is a thermoreflective thin-film coating. This chapter classifies its energy effect and openly names the limits of the assessment — in particular in relation to classic insulation materials and to the German Buildings Energy Act (GEG).
What do the system's λ values mean?
The stated λ values (e.g. 0.000120 W/mK) are system performance values, determined under defined test conditions (hot-box method). They do not correspond to the thermal conductivity of a material within the meaning of the standards EN 12667 or EN 12664.
Is this a classic insulation material?
No. It is a thermoreflective thin-film coating whose effect is based on radiation reflection and reduced heat conduction — not a volume-insulating material with a declared design value λ.
Does the system replace a U-value verification per GEG?
No. Since there is no material λ per EN 12667/12664, the system cannot simply be inserted into a U-value calculation. An energy verification per GEG is project-specific and must be carried out by a qualified person.
How does the system behave with regard to moisture?
The overall build-up (primer + functional layer + top coat in combination) is vapour-permeable with a calculated system value of sd ≈ 0.44 m (class V2 per EN 15824) and has low water absorption (class W3). This is favourable for the moisture balance; the specific condensation protection must nevertheless be checked per object.
Energy effect — classified correctly
The thermoreflective effect can influence the heat input through radiation and the surface temperatures. These effects are real, but strongly dependent on boundary conditions (orientation, solar exposure, substrate, climate) and cannot be translated wholesale into an equivalent U-value. Statements on energy savings must therefore always be considered in the specific application.