Using Digital Twins to investigate the need for active cooling systems in Danish public buildings

When it comes to energy consumption in buildings, Denmark is not an exception, where the building sector contributes to around 35% of the overall energy consumption in the country, with a comparable share in greenhouse gas emissions. Traditionally, most of the energy used in Danish public buildings is devoted to satisfying the demands for heating, hot water, ventilation, lighting, and equipment. On the other hand, such buildings are rarely equipped with cooling systems, even in newly built facilities, and rely mainly on passive techniques and mechanical ventilation systems to provide good indoor thermal comfort in the summer. However, the rise in average ambient air temperatures in recent years has opened the discussion wide on the need to equip public buildings in Denmark with active cooling systems to satisfy the cooling loads of the summer months. In this work, a case study of a public university building is considered a case study to investigate the impact of the rise in ambient air temperatures on the overall indoor thermal comfort levels in addition to assessing the need for active cooling systems in such facilities. The case study considered is relatively modern in terms of envelope design and energy supply systems. It has no active cooling systems and relies mainly on mechanical and natural ventilation to establish indoor comfort. A building energy model is developed and calibrated using actual data collected from the building. The building twin is used to predict the impacts of the increase in the ambient air temperatures and global solar irradiation on the cooling energy demand and indoor thermal comfort. The results highlighted a major increase in the cooling load of the building as well as the energy consumption to satisfy the cooling needs. In addition, major violations to the indoor thermal comfort requirements were reported which demonstrates the need for active cooling solutions in public Danish buildings.