Climate change and ideal thermal transmittance of residential buildings in Iran

Climate change will make the Iranian climate hotter and drier. This increase in the harshness of the boundary conditions poses a new question of whether today's high-performance buildings, whose envelope thermophysical properties are optimized for the current climate, will underperform. Therefore, it is important to (i) identify the regions in Iran that will lead to such underperformance and (ii) determine to what extent the thermophysical properties will need to change to remain optimal. This paper determines and compares the ideal thermal transmittances (U-value) of residential building envelopes for current and future climate scenarios. The EPSAP generative design method created twelve thousand buildings with random geometries to evaluate their energy demand for heating and cooling in EnergyPlus. The U-values of the envelop elements for these buildings were randomly assigned and simulated for 21 locations in Iran for the current period and two future timeframes (2050 and 2080). The future weather was created using the Future Weather Generator tool to morph today's typical meteorological weather to match the EC-Earth3 data for the SSP5-8.5 scenario. The results confirm that climate change will significantly impact the energy performance of a building. However, consequences and mitigation actions will differ depending on the region. Future ideal U-values will be higher or lower than today's values in the center and northern regions, which are characterized by low to high heating demand in the present day. In locations with already high cooling needs, buildings will require lower, or the lowest possible, U-values in the future. Therefore, building professionals must incorporate climate projections in their design performance assessment. In addition, policymakers must implement building codes and guidelines that consider the anticipated impacts of climate change on building performance in different regions of the country.