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The main goal of the EU Horizon 2020 project CoNZEBs was to identify technology combinations for multi‐family houses that fulfil the Nearly Zero‐Energy Building (NZEB) requirements but result in lower investment costs if compared to the typical (mainstream) NZEB technology combinations. The national CoNZEBs teams from Germany, Denmark, Italy and Slovenia were successful in finding at least four alternative technology combinations(aka alternative NZEB solution sets) per country. These solution sets and many of the contained innovative technologies are described in detail in a report [1] available on the project website. In a second step the NZEB solution sets and a technology combination achieving a building energy level beyond NZEB (zero energy building or plus energy building) have been assessed in comparison to the typical NZEB and a building fulfilling the national minimum energy performance requirements regarding life‐cycle costs and life‐cycle impact[28].This report now seeks to look ahead into future developments of certain factors that have an impact on the energy performance, investment costs or energy costs of the determined solution sets. The relevant impact factors are primary energy factors, energy prices, technology costs and technology efficiencies. For each of these impact factors the developments by the year 2030 were predicted, based on available national studies or where not available based on the personal evaluation of the project partners. The main goal of the EU Horizon 2020 project CoNZEBs was to identify technology combinations for multi‐family houses that fulfil the Nearly Zero‐Energy Building (NZEB) requirements but result in lower investment costs if compared to the typical (mainstream) NZEB technology combinations. The national CoNZEBs teams from Germany, Denmark, Italy and Slovenia were successful in finding at least four alternative technology combinations (aka alternative NZEB solution sets) per country. These solution sets and many of the contained innovative technologies are described in detail in a report [1] available on the project website. In a second step the NZEB solution sets and a technology combination achieving a building energy level beyond NZEB (zero energy building or plus energy building) have been assessed in comparison to the typical NZEB and a building fulfilling the national minimum energy performance requirements regarding life‐cycle costs and life‐cycle impact [28].This report now seeks to look ahead into future developments of certain factors that have an impact on the energy performance, investment costs or energy costs of the determined solution sets. The relevant impact factors are primary energy factors, energy prices, technology costs and technology efficiencies. For each of these impact factors the developments by the year 2030 were predicted, based on available national studies or where not available based on the personal evaluation of the project partners.

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. 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.

Solution sets are collections of energy efficient technologies used in nearly zero‐energy buildings (NZEB) that in the specific case constitutes a building that meets the national NZEB requirements or beyond. A solution set may vary from one context or location to another and may include any number of technologies. Solution sets have the potential of reducing the cost of currently realised NZEB projects, i.e. a combination of technologies that support/supplement each other in striving towards NZEB at less investment cost. A solution set reduces the overall investment cost for a NZEB. This is achieved either by introduction of less costly solutions in general or by implementing combinations of cost and performance reductions in combination with other cost and performance improvements.

Costs associated to energy performance of buildings are generally assessed taking into accounts purchase and installation of materials, components, goods of building and energy system technologies, without taking into account other issues that can significantly impact on the final construction costs. Such additional costs include: design, permits, urbanisation works, organisation and operation of the building site, preliminaries, insurances, final inspections and tests. Analogously, operation costs are generally limited to energy consumption for the different vectors, without taking into account the maintenance costs, whose percentage on total operational costs can be relevant in the long‐term, due to the small energy uses in NZEBs and to the complexity of building technologies and energy systems in high performing buildings.

This report documents the work of the CoNZEBs project on setting the cost baselines for different building energy performance levels. It analyses and compares the investment and energy costs in four different countries (Germany, Denmark, Italy and Slovenia) for: ⌂ New multi‐family houses built according to current national minimum energyperformance requirements⌂ Existing examples of NZEBs (nearly zero‐energy building) multi‐family houses⌂ Multi‐family houses that go beyond the NZEB‐levelThe work is based on literature on building costs, on the knowledge gained by the different research organisations and complemented by the cost experience of the national housing organisation. The work of Concerted Action EPBD on NZEBs is used as well. The result of these efforts is the starting point (baseline) for evaluating the technical solution sets for nearly zero‐energy buildings that were identified to reduce the additional costs currently required to build a better energy performing multi‐family house than determined by the minimum energy performance level of the national building laws. This exercise will be documented in deliverable D2.2 “Comparison of costs for new multi‐family houses, NZEBs and beyond”.

Green building concept plays a fundamental role in reducing the use of resources and the impacts on human health and environment, during the whole building life cycle. Therefore, a method to measure the building sustainability rate is crucial for comparing various alternatives in terms of use of different materials, energy resources, production processes to reduce energy consumption and environmental impacts. Many protocols have been proposed to perform buildings’ sustainability evaluation; however, different operators applying these certification tools might need to make hypotheses, even different from each other, to complete the whole procedure. Hence, this work aims to evaluate whether and how the hypotheses formulated by each operator can influence the final certification level. To this end, a Round Robin Test among international partners was performed using different versions of LEED sustainability protocol to the same building with the same boundary conditions, comparing and analyzing the results provided by the participants. The final aim was to identify which issues have more influence on the final performance rate, giving to the users a deeper knowledge of the aspects included in these procedures. The results showed the potential of these building environmental certification systems, capable of offering a transversal level of environmental sustainability.