Comparison of models for estimating air infiltration in dwellings and their impact on heating demand

Buildings are not airtight, leading to air infiltration, defined as the uncontrolled flow of outdoor air into indoor spaces. These airflows have a detrimental impact on energy demand and consumption, making their accurate estimation in building energy performance assessment tools essential. In Spain, the current tools allow the use of four infiltration models: N-factor, LBL, AIM-2, and EN 16798–7. This study compares these four approaches using TRNSYS energy simulations applied to a real single-family dwelling. The building envelope was characterized by performing a Blower Door Test, and the analysis was extended to eight cities with different climatic conditions. The maximum difference in the estimated energy impact among the models ranged from 6.1% to 12.2%. In climates with mild winters and higher wind intensity, the differences between models were less pronounced, ranging from 1.29 to 2.57 kWh/m 2 ·year. Conversely, in colder climates with lower wind intensity, the differences were substantially higher, ranging from 2.8 to 7.37 kWh/m 2 ·year. These results highlight the importance of selecting an appropriate infiltration model based on climatic conditions. For colder climates with low wind intensity, the AIM-2 and EN 16798–7 models are recommended.