Practices

Spreadsheet with LCCs: a database for benchmarking actual NZEB life-cycle costs of the case studies

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The EPBD recast established that all new buildings have to reach by the end of 2020 the nZEB target set by the Member States. The scope of this report is to provide a CRAVEzero cost spreadsheet, implementing a comprehensive and structured methodology in order to evaluate the LCC with a particular focus on nZEBs.

 

Methodology adopted

The first part of this report describes the approach adopted for collecting the information and the methodology for evaluating the Life-Cycle Costs implemented in the CRAVEzero spreadsheet and for the evaluation of the case studies. A data collection template for the evaluation of the nZEB life-cycle costs was developed as a starting point for the upcoming CRAVEzero LCC tool. The template is structured according to the approach provided by two main sources:

 

  • The Standard ISO 15686-5
  • The European Code of Measurement, elaborated by the European Committee of the Construction Economists

The tool PHPP was used for the energy performance analysis. This tool summarises all the information dealing with the energy-related features of the building components and services and provides a comprehensive overview of the technologies installed. The data collection for the CRAVEzero spreadsheet is structured in three parts:

 

  1. General project information: it includes the main information of a case study and its context
  2. Non-construction costs: it deals with the preliminary costs for the WLC and the design phase
  3. Life Cycle Costs: it reports all the costs for building elements and services during construction and operation, including maintenance and energy costs

Energy costs

In particular, for estimating both the energy costs and the revenues (due to the renewables installed), the following contributions, in terms of final energy, were considered:

 

- Energy costs:

  1. Heating demand [kWh]
  2. Energy demand for domestic hot water production [kWh]
  3. Cooling demand [kWh]
  4. Household electricity [kWh] + electricity demand for auxiliaries [kWh]

- Revenues from renewables

  1. Final energy generated by a system
  2. Final energy generated by the thermal system

Maintenance costs

The analysis within CRAVEzero is based on standard values from EN 15459:2018 that provides yearly maintenance costs for each element, including operation, repair, and service, as a percentage of the initial construction cost. For the passive building elements, an average yearly value accounting for 1.5% of the construction cost has been assumed for the evaluation. The value has been cross-checked with average values coming from the experience of the industry partners.

 

Normalisation

The analysed case studies are located in different European countries, i.e. Austria, Germany, France, Italy, and Sweden, with specific characteristics in terms of climate conditions, construction, and energy market. Therefore, in order to compare the results of the case studies and to draw a general overview of the costs of the current nZEB practices, a normalization of the collected data is needed. In particular, the construction costs have been normalised considering the data from the ECC (European Construction Costs) that calculated a European construction cost index that quantifies the ratio among the construction costs of EU countries. For the climate conditions, the normalisation has been carried out considering the Heating Degree Days of the building locations. Concerning the energy process, a common value has been adopted.

 

Presentation of the results – case studies comparative analysis

The second part reports an overview of the results, with the comparison of relevant indicators, costs, and performances among the case studies considering the effect of local specificities, different context and use of the buildings (i.e. normalised results).

 

The results show how the investment costs for design, material labour and other initial expenditures is around 60% of the LCC, while the energy and maintenance account for around 40%. As it was expected, the energy costs during the life cycle of a nZEB represent a minor contribution to the LCC, with an average of around 15%. Looking at the breakdown of the cost for the building elements, and highlighting the impact on the construction costs, results show that in some cases the structural elements represent a significant contribution to the construction, according to the complexity and the dimension of the building. On the other hand, nZEB related technologies have a small impact on the construction costs, although in comparison to a traditional building the cost for the HVAC system and the integration of renewables is more significant.

 

CRAVEZero Spreadsheets

Finally, the third part of the report presents 12 dedicated technical tables, summarising the main results and indicators calculated with the CRAVEzero spreadsheet (i.e. actual results without normalisation).