Globally increasing prices of energy have result in raise of thermal qualities of building envelopes.Consequently, these heavy insulated constructions are facing undesirable phenomena – for instance a riskfor occurrence of frost formation and condensation together with a changed thermal field in buildingconstructions. Condensed moisture, as well as moisture trapped in thermal insulations during build-up, canalso affect an increased dust contamination, algae or mould growth and structural damages.
This contribution reports on a laboratory experiment aimed at growth of frost formation and moisturecondensation in stone wool opened to air for specific temperature fields – namely (+20; -20ºC), (+20; -15ºC),(+20; -10ºC), (+20; -5ºC) over fibrous specimens with varying density. Air on warm side of material sampleswas saturated with moisture. Frost accumulated with time in the part of specimens facing the cold air. In thepart facing the warm humid air a condense formation occurred. The wider thermal field and higher density ofmaterial samples we used the more distinct border between frost and liquid condensate we observed. Alsomoisture resistance factor μ, as a basic moisture characteristic of an insulating material, had an upwardtrend for broader temperature intervals.
Next to the loss of insulating qualities, annual repetition of condensation and frost growth in stone wool cancontribute to degradation of the material structure, thermal losses and, in consequence, higher energyconsumption.
2008. 1035-1039 p.
stone wool, material properties, frost formation, condensation, moisture resistance factor