To limit the probability that the overall thermal transmittance will be unacceptably high, which could lead to excessive thermal transfer through the building envelope, which could lead to excessive use of energy, which could lead to an unacceptable effect on the environment.
To clarify that portions of a foundation wall that are above ground and where the top of the foundation wall is less than 0.4 m above the adjoining ground level are permitted to be treated as above-ground walls .