To limit the application of the trade-off path.
This is to limit the probability that the effective thermal resistance of above-ground opaque building envelope assemblies with embedded heating or cooling systems will be unacceptably low, which could lead to inaccuracy of the trade-off model, which could lead to underestimation of the energy use attributed to the building envelope of the proposed building, 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.