[Clause 9.36.2.4.(3)(a)] To limit the probability that penetrations by major structural members are not properly insulated, which could lead to excessive thermal transfer through the building envelope, which could lead to excessive use of energy for heating and cooling, which could lead to an unacceptable effect on the environment.
[Clause 9.36.2.4.(3)(b)] To limit the probability that the effect of large areas of major structural members will not be accounted for in the calculation of the effective thermal resistance of assemblies, which could lead to an overestimation of the effective thermal resistance of the assembly, which could lead to excessive thermal transfer through the building envelope, which could lead to excessive use of energy for heating and cooling, which could lead to an unacceptable effect on the environment.
[Clause 9.36.2.4.(3)(b)] To exempt from the calculation of effective thermal resistance the effects of sufficiently small areas of major structural elements that completely penetrate the building envelope, on the basis that they do not significantly affect the effective thermal resistance of the assembly.