Co-simulating the effects of nature-based and conventional composite facades on building thermal and energy performance in temperate climates

The choice of building façade materiality and composition plays a significant role in indoor and outdoor thermal comfort as well as energy efficiency. However, the carbon footprint of most construction materials contributes negatively to climate change, reinforcing the need for Net-Zero Carbon Buildings (NZCBs). Incorporating nature-based materials into façade compositions can help minimize carbon emissions in the building sector. However, their effects on indoor-outdoor climate interactions and energy conservation is less well studied. This study analyzed the impact of six different façade compositions — comprising a reference (all concrete), two brick-based designs, two stacked bio-based insulations, and a mixed concrete-bio-based material (hempcrete) — on indoor energy consumption and outdoor thermal conditions using a co-simulation approach with ENVI-met and EnergyPlus. The results showed that during summer, all façade scenarios exhibited warmer external wall surfaces during the daytime, with brick-based walls cooling down while bio-based insulated walls remained warmer at night. In winter, all walls were cooler throughout the day and night. The Mixed Hemp-Crete (MHC) façade consistently stayed cooler across seasons. Other façade compositions influenced ambient air temperature, with daytime warming and nighttime cooling effects observed during summer, indicating the potential of these materials to mitigate urban heat. Peak summer energy consumption increased by 12%–98% across the façade scenarios due to variations in composition, whereas winter energy consumption decreased by 25%–68% compared to the fully concrete façade system. Annually, stacked and mixed bio-based façade scenarios demonstrated a heating consumption reduction of 48%–52%, highlighting their potential to lower energy consumption in regions with long, cold winters. These findings emphasize the significant contribution of nature-based façade materials to global carbon mitigation efforts, offering a promising pathway toward achieving NZCBs.