What is the difference between a radiant heat barrier and a conductive heat barrier?
From a scientific point of view, the formulae used to calculate heat transfer by conduction and radiation are as follows: For conduction: q” = (T OUTSIDE – T SURFACE/ΣR) For radiation: q” = εσ(T4 SURFACE – T4 SURROUNDINGS), Where, ΣR = sum or total of thermal resistances ε = surface thermal emissivity σ = 5.67 x 10-8 (Stefan-Boltzmann constant) An effective conductive heat barrier (insulating against heat transfer by conduction) reduces the heat transfer by copnduction by providing thermal resistance (R-value). This is where mass insulation such as fiberglass wool. polystyrene, etc. come into play. The main drawback to conductive insulation relates to thickness. The thicker the better. A secondary bu equally important drawback of mass insulation is its degradation and consequent loss of R-value with again or with water (vapor or liquid form) absorption.) An effective radiant heat barrier (protecting against heat transfer by radiation) will stop the heat from entering the building and a
