Energy loss due to ventilation: impact of average values and simplifications on calculations.

The project of CEN Standard from the Ventilation for dwellings group TC156/WG2/AH4 [1]for airflows calculations is being submitted to enquiry.This method can be easily compared to AIVC guides to calculate the ventilation airflow(natural or mechanical) in a given status. Yet, for energy loss estimation, these airflowscalculations must be done either hour per hour, either with average values andsimplifications. The aim of this study is to determine the real influence of each parameter inAH4 calculations and the impact of the method on energy results of simplifications that couldbe made in.We have modelised a four-storey dwelling building. On each floor, there are three flats.The real building is situated near Paris but for the purpose of the study, we have simulateddifferent sites in France.Ventilation in the building was simulated to be either natural or mechanical (exhaust system)which were dimensioned according to French state of the art and regulations.