To limit the probability that piping and standby losses of service water heating systems will be calculated and applied differently for the reference and proposed houses, which could lead to the effect of these losses on energy consumption being treated differently in the proposed and reference houses, which could lead to inaccuracy of the model, which could lead to overestimation of the energy used by the reference building or underestimation of the energy used by the proposed building, which could lead to excessive use of energy, which could lead to an unacceptable effect on the environment.