Ventilation rates and control strategies in VAV systems: Effects on energy consumption in office buildings in consideration of the EPBD and EN 16798 standards

The study extends previous work on determining outdoor air flow rates in non-residential buildings, shifting the focus from simply complying with indoor air quality requirements to assessing the energy effects on systems. The design flow rates obtained using different calculation methods, including EN 16798 part 1 and the Italian National Annex, are taken as a basis for analysing the energy performance of a variable flow ventilation system, in line with the objectives of EPBD 2024 on decarbonisation and in-door environmental quality. The assessment applies a dynamic simulation model of a variable flow primary air system, representative of a typical office building. The model is applied to a matrix of scenarios that combines the flow rate calculation method, air quality category, air diffusion strategy in the environment and fan control logic. The results quantify the energy impact associated with different regulations and control methods, highlighting the trade-offs between energy consumption, indoor air quality and thermal comfort in occupied spaces, and providing selection criteria for the design and refurbishment of ventilation systems in office buildings; in particular, it is noted that the two control methods investigated enable annual savings in primary energy of 51% and 53%.