Modelling of radiative heat transfer in building envelopes

journal article - other

English

Heat propagation in buildings, namely in their envelopes, is determined by quasi-periodic climatic conditions from external environment and by insulation and accumulation properties of particular material layers. A typical phenomenon of many reconstructions of large block of flats from the socialist period in Czechoslovakia is the presence of algae and the consequent surface degradation of new insulation systems; the same can be observed even in case of new building objects, even of those with insulation layers made from special modern materials. This phenomenon can be explained by the night condensation of vapour from porous material structures, driven by the thermal radiation from building envelopes to the clear sky. Consequently, reliable computational modelling of heat transfer should include both time-variable heat conduction and convection through particular constructive and insulation layers and short-wave (from sun through atmosphere to earth surface) and long-wave (back to atmosphere) radiative supplements, coupled with propagation of moisture in various phases in pores, although some of above sketched processes cannot be easily characterized by deterministic mathematical relations. The quantitative analysis of radiative components is significant for all producers of outer coatings because the decrease of emissivity is able to avoid condensation of vapour at all.

heat and moisture transfer in buildings, porous material structures, thermal insulation, thermal accumulation, short- and long-wave radiation, numerical modelling, laboratory measurement methods

VALA, J.; ŠŤASTNÍK, S.; STEUER, R.

2007

1. 9. 2007

Slovenská štatistická a demografická spoločnosť

Bratislava

1336-7420

Forum Statisticum Slovacum

3

2

Slovak Republic

223

228

6