Solutions sets for cost optimisation of nearly zero energy buildings (NZEBs) in four European countries

Nearly zero energy buildings (NZEBs) are required as the minimum standard for all new buildings in Europe by January 2021. NZEBS should, according to the Energy Performance of Buildings Directive (EPBD) [1], be cost optimal, i.e. the cost of constructing and operating the building over its lifetime should be at its minimum. The EU Horizon2020 research project CoNZEBs, identify and assess technology solution sets that lead to cost reductions of new NZEBs in four EU member states. Focussing on buildings that comply with national NZEB requirements, designers can easily ignore alternative solutions that make the building cheaper while remaining within national requirements. This is not done intentionally, but primarily due to use of a traditional design thinking where optimisation is done on component level instead of a more holistic approach. Changing one building component may influence the cost and performance of other components. These alternative solutions take offset in a typical national multi-family building design and analyses the different lifetime costs in terms of costs for construction, and energy. Analyses of costs in different countries reveals different solutions sets being optimal. In CoNZEBs we compare different solution sets and investigate the possibility for "exporting" solution sets from one country to another.