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EU CoNZEBs report: Solution sets for NZEB multi‐family houses and beyond assessed for 2030

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Title page of the EU CoNZEBs report 'Solution sets for NZEB multi‐family houses and beyond assessed for 2030'

Title page of the EU CoNZEBs report 'Solution sets for NZEB multi‐family houses and beyond assessed for 2030'

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 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.


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. With the updated impact factors new energy and cost results were calculated and compared to the original results with the status 2018. This allowed for a basic identification of the “future-proof” alternative solution sets that will stay or become more financially attractive in the next approximately 10 years. In addition, the impact of climate change, further developments in the national building energy performance assessment methods and possible financial support programmes were discussed.


The typical multi-family houses, the mainstream NZEB technology combinations and based on that also the alternative NZEB solution set as well as the beyond NZEB level differ among the four countries due to different building culture, different energy performance requirements, different climate, different technology costs, etc.


Some of the national alternative solution sets are based on singular changes (e.g. different insulation material) while others contain combinations of different heating and ventilation systems with accordingly adapted insulation levels of the building envelope. This includes solution sets with electrical heat pumps or direct electrical heating, both in combination with a PV system. Therefore it is challenging to identify the “most future-proof” solution set across all the involved four countries.


However there are two conclusions valid for all four countries:


  • The building energy performance level beyond NZEB becomes financially more attractive when taking the changes at the impact factors in 2030 into account. Payback times for the additional investment costs in comparison to the typical NZEB get smaller, due to comparably lower technology costs for mainly heat pumps and PV systems and still rising technology efficiencies.
  • Alternative NZEB solution sets with electrical heat pumps or (where allowed) direct electrical heating systems, both in combination with PV arrays, benefit from the changes at the considered impact parameters in the year 2030 if compared to the typical NZEB solutions.

Read more about the national assessments and main conclusions in the final report.




The CoNZEBs project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement no. 754046.


The report reflects the author’s view. The Commission is not responsible for any use that may be made of the information it contains.


In Germany, national co‐funding is provided by Bundesministerium für Umwelt, Naturschutz, Bau und Reaktorsicherheit within the research initiative Zukunft Bau (SWD‐‐17.33).