A NEW APPROACH CHANGING EXPECTATIONS FROM SOLID PARTS OF BUILDING ENVELOPES: TESTING THE CARBON DIOXIDE DIFFUSION AND RETAINING PERFORMANCES OF BUILDING MATERIALS

Contemporary building technology focuses on fully airtight building envelopes supported with mechanical or hybrid ventilation systems for energy-efficient buildings and healthier indoors. In fact, during COVID-19 pandemic and associated lock-downs, people realized how valuable fresh air is in built environments. Experts and governments promoted natural ventilation to meet higher air change rates. If mechanical ventilation is the only option, it is recommended to stop recirculation and feed the indoor air with 100% outdoor air (ASHREA, 2020; REHVA, 2021). These recommendations are quite challenging for a sustainable construction sector aiming at energy efficiency. This challenge presents an opportunity to think out of the box. In other words, this situation awakens curiosity to other undiscovered horizons beyond the common approach which encourages fully airtight built environments and advanced mechanical ventilation solutions. Here, this study asks a striking question: “What if the key to healthier indoor air is the breathable building envelopes?” This question may be considered as a paradigm shift for the building science community obsessed with airtightness. In fact, the concept of breathable walls is not new, but this hitherto underestimated approach is worth reconsidering.