The EU-Horizon 2020 project CRAVEzero focuses on proven and new approaches to reduce costs and improve nZEBs at all stages of the life cycle. The main goal is to identify and eliminate the extra costs for nZEBs related to inefficient processes and technologies and to promote innovative business models taking into account the cost-effectiveness for all the stakeholders.

Figure: Cravezero Approach

Cost reduction potentials are to be found in all life- cycle phases of nZEBs – from urban planning, to building design, construction and building operation. Also, it is necessary to consider indirect co-benefits such as architectural quality, indoor environmental and comfort improvements and health aspects. The high complexity of nZEBs both in a technical way as well as difficulties in planning, construction and operation processes, are the main reasons why nZEBs fail to achieve performance and costs targets. Already from the very beginning, prerequisites must be created to define the requirements and clear project objectives. Too often, promising building concepts fail to achieve costs and energy goals, because project participants are not sufficiently aware of the manifold interactions of holistic planning contexts.

The idea of “CRAVEzero” is to promote a well organized and transparent interdisciplinary process along the whole life cycle of a nZEB, focussing both on environmental and economic aspects .

To minimize risks and possible bottlenecks, obstacles must be identified at an early stage. It is necessary to establish a common planning understanding for nZEBs among all actors early on. The design of new nZEBs begins with maximizing passive design, yet limiting energy consumption from the grid. To do this, planners often need to challenge the norms of traditional designs.

Figure: Steps to reach nZEB standard[AK1] 

Each building has its unique process, where architects often start from scratch, collect the information and constraints of the local context, develop the building, carry out cost-optimal performance analyses, hopefully include an evaluation of the potential for using renewable energy. This means extra time and planning costs for the design process. Stakeholders repeat almost the same procedures without a coordinated and standardized process. As a starting point, a systematic approach for the life cycle process of low-cost nZEBs is needed. A clear connection between the building performances and the related costs is essential for ensuring the clarity of the process. A strategic element in the whole process is the introduction of a performance-based procurement approach as a common practice not only for public tendering but also for private construction.

Figure: Process steps to reach nZEB-standard along life cycle phases

Cost reduction and marked acceleration for nZEBs have been achieved using the following guiding principles, established by the CRAVEzero consortium:

  • Define energy and related project goals.
  • Define actions to reach the goals and track them throughout the life cycle.
  • Create win-win situations for all stakeholders.
  • Select optimal nZEB technical solution sets.
  • Do life cycle cost analysis and variants.
  • Quantify co-benefits for nZEBs.
  • Learn from frontrunners and avoid pitfalls and bottlenecks.
  • Bring all together in the business case for nZEBs.