The paper presents a dynamic approach of the validation process of existing building simulation model. The normalization of the simulation results and the division of the electricity and gas bill are realized by taking into account the balance point temperatures for appropriate degree-days. These temperatures, as it was shown in this paper, could change during the validation process, as opposed to most cases where these temperatures are arbitrary fixed for the whole process. Heating, cooling and basic monthly energy consumption are taken into account in the proposed validation process. This approach allows the user to target specific building or HVAC elements which can be modified during validation. The modifications concern only the data collected with the truthfulness degree considered as not very good. The paper presents the validation process, applied to the computer-assisted energy analysis of an existing building located in Quebec.