It is unrealistic to rely on empirical rules to establish forms of constructions which provide satisfactory resistance to heat transfer as well as weather resistance, strength and stability and many of the other performance criteria. Moreover, current construction methods are generally less bulky
than those used years ago, as greatly reduced thicknesses of materials are employed in combination with each other, each layer, leaf or skin perhaps fulfilling only one very specific function. The thermal comfort properties of these materials used in combination can only be assessed by calculating the amount of heat transfer from internal to external air (in cold climates). The thermal resistance
properties of each layer must be taken into account, along with other factors relating to their surface texture and juxtapositions within the construction.