nZEB Case Studies

There already exist pilot projects across Europe, which may be called nZEB buildings. They are not easy to compare because of variation in the definitions and performance levels—nZEB definitions have not yet been available when these buildings have been designed. It is important to check which energy uses are included in the calculated and measured energy performance and are the results reported as delivered or primary energy. Tenant’s electricity (appliances, lighting) is often not included. Simulated primary energy is typically between 50 and 100 kWh/(m² a) for high-performance nZEB buildings with on-site renewable energy production if all energy uses are included. Such buildings may be extremely complicated, e.g. control of mixed mode ventilation or integrated energy supply solutions with storage and many operation modes. “Overkill” complexity may have implications on operation and maintenance as nobody cannot manage systems, which are not easy to control and operate. Another trend that can be seen is simple and reliable solutions based on high-performance components and careful system design and fitting with building properties. In the following, five nZEB buildings across the Europe are reported. Three of them are with measured energy data, indicating that strict targets are not always easy to achieve; however, some deviations have been caused also by unrealistic energy calculation input data. Technical solutions used show that there are many alternative ways to achieve high performance; however, strong differences in design bases and basic solutions in similar climate may also show that optimal solutions are always not known or found. Four first case studies are mostly focused on description of technical solutions, but the last one also describes the tuning of systems needed in the first year of operation to achieve the targets.