Viability of free-running buildings in the Nordic region

In the nexus of accelerating climate change, energy crisis, and resource depletion, this paper contributes to the development of radical resilient building design solutions. Buildings today rely on significant energy for operation, and in the Nordic region, this is primarily for indoor space conditioning. Until now, the predominant focus of building science research was on increasing energy efficiency and reducing carbon emissions reduction. The gravity of the climate emergency may have been underestimated, implying great vulnerability of HVAC systems, and meaning that humans will soon have to adapt to a radically different life without affordable and abundant energy. Therefore, this study aims to counter this risk by devising a free-running building design in the Nordic context: a building that achieves thermal comfort and indoor environmental quality without using any energy for heating, cooling, or mechanical ventilation. A specific existing free-running building from an non-Nordic context, “2226” in Austria, was analysed in detail and used as a baseline design for creating a free-running concept for the Nordic countries. A building model was created and simulated in IDA ICE, applying various generated future weather files based on the worst-case climate projections for several Nordic locations. Additionally, the building materials and control systems were simulated parametrically to assess the influence of thermal inertia, thermal transmittance, and natural ventilation. Building performance was evaluated based on the thermal adaptive comfort model, relative humidity, and indoor carbon dioxide concentration. Simulation results show that for many Nordic locations, free-running buildings were not viable due to insufficient internal heat gains. In colder locations, the requirements of thermal comfort and indoor climate could not be satisfied simultaneously during winter. In the southernmost Nordic locations, the study revealed future overheating risks, which could be reduced by thermal inertia. The research suggests that higher internal gains and different occupancy patterns could enhance the thermal autonomy of residential buildings. The model setup merits further optimization, which might lead to better overall performance. The outcomes of this research are significant because they offer a pathway to a more resilient building design framework. By reducing reliance on HVAC systems, the application of passive design strategies could lead to substantial energy savings, while maintaining thermal comfort and a healthy indoor climate.