The calculation of influence of the ventilation system on the energy performance of buildings is mainly related to the following standards:
First of all the energy demand for ventilation is calculated by EN13790 as a building characteristic taking into account the required indoor environment (ventilation rates from EN15215 or infiltration rates from EN15242).
In EN 15242 the air flows are calculated both for mechanical, hybrid and passive ventilation. The calculation for mechanical systems is based on the required air flows from EN15251/EN13799. The values are corrected to take into account factors like: position of the air handling unit (indoor or outdoor), the switching on-off, ventilation effectiveness, accuracy of the system design, air flow through duct leakages, air leakages of the air handling unit and air recirculation, if any. For passive and hybrid duct ventilation the aim of the calculation is to calculate the air flow in the system taking into account the outdoor and the indoor conditions. The method provides the relationship between the air velocity in the duct and the pressure loss through the cowl which depend on the outside weather conditions taking into account, wind air velocity outside the building, pressure loss coefficient of the cowl, roof angle and the position of the cowl.
The energy need for a ventilation system can then be calculated according to EN15241 taking into account energy needs for fans, pre-heating, pre-cooling, efficiency of heat exchangers, humidification, dehumidification and energy losses in ducts.
An important issue is the boundary between EN13790 and EN 15241 to avoid calculation the effect of the same measure twice (heat recovery). Specific design guidelines and requirements to ventilation systems are listed in EN13799. The guidance for design given in this standard and its annexes are mainly applicable to mechanical supply and exhaust ventilation systems, and the mechanical part of hybrid ventilation systems.
In complement to these standards, the EN 13141 defines test methods for ventilation components: