Thermal resistances of air in cavity walls and their effect upon the thermal insulation performance

The optimum thickness in cavity walls in buildings is determined under steady conditions; the heat transfer has been calculated according to ISO 15099:2003. Two forms of masonry units are investigated to conclude the advantage of high thermal emissivity. The paper presents also some results from a study of the thermal insulation performance of air cavities bounded by thin reflective material layer "ε = 0.05". The results show that the most economical cavity configuration depends on the thermal emissivity and the insulation material used.