<span class="word">Which <span class="word"><span class="changedDisabled">Is <span class="word">the <span class="word"><span class="changedDisabled">Most <span class="word"><span class="changedDisabled">Suitable <span class="word"><span class="changedDisabled">Ventilation <span class="word"><span class="changedDisabled">System <span class="word">for <span class="word"><span class="changedDisabled">Residential <span class="word"><span class="changedDisabled">Buildings? <span class="word">Case <span class="word"><span class="changedDisabled">Study <span class="word">in <span class="word"><span class="changedDisabled">Northern <span class="word">Spain

This study evaluates simple exhaust, relative humidity-controlled and heat recovery ventilation systems in northern Spain (SEV, RHCV, HRV systems) through simulations of IAQ, energy, and exergy performance. The IAQ analysis reveals poor performance of the RHCV system for indoor source pollutants such as formaldehyde and TVOC. The HRV system demonstrates superior energy efficiency, with 30% lower primary energy consumption than the SEV system, though it is necessary to evaluate whether the heat recovered compensates for the increased fan energy consumption. This condition is evaluated by defining an outdoor air temperature limit value. The exergy analysis shows the HRV system requires 30% less primary exergy than the SEV system despite higher system demand. While HRV emerges as the optimal solution for balancing IAQ and energy performance, the findings highlight that source control remains necessary to effectively manage HCHO and TVOC concentrations. The research provides guid-ance for selecting ventilation systems that minimize pollutant exposure while opti-mizing energy resources.