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OVERVIEW - Energy Performance Requirements Using the Cost-Optimal Methodology

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The recast Energy Performance of Buildings Directive (Recast EPBD) states that Member States must ensure that minimum energy performance requirements for buildings are set “with a view to achieve cost-optimal levels”. The cost-optimal level must be calculated in accordance with a comparative methodology. The ultimate goal of this is to achieve cost-optimal improvement in the energy performance of new and existing buildings. The Concerted Action EPBD supports Member States by exchanging experiences of implementing a cost-optimal methodology.


Here you can download the PDF version of this Overview article (see below under 'Additional documents').

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Implementation of the cost-optimal methodology according to the Recast EPBD

Cost-optimal levels are defined as the energy performance level which leads to the lowest cost during the estimated economic lifecycle. Member States will determine this level taking into account a range of costs like investments, maintenance, operating costs and energy savings. The economic lifecycle is defined by each Member State.

There is a legal document, the Regulation based on a CEN package of standards, which is accompanied by Cost-Optimal Guidelines outlining how to apply the framework for calculating the cost-optimal performance levels of minimum energy performance requirements for buildings and building elements. Member States shall use either the relevant existing CEN standards for the calculation of energy performance or an equivalent national calculation method provided that the latter is in accordance with Article 2(4) and Annex I to Recast EPBD.

The Regulation is an instrument to guide Member States in the process of checking the minimum levels of energy performance in building stock. The aim is to have national energy performance requirements as close as possible to the outcomes of the cost-optimal approach. If there are significant differences exceeding 15 %, the Member States need to explain this difference. In case the difference cannot be justified, a plan needs to be developed by the respective Member States, outlining appropriate steps to reduce the gap.

According to the Regulation 21 March 2013 is the deadline for establishing and submitting Member States reports to the European Commission on cost-optimal calculations of the minimum energy performance requirements.

Cost-optimality can be considered from several different perspectives, each of which will provide a different result.

The two main important perspectives are:

  • the societal (“macro” economic) and
  • the private investor (“micro” economic).

The European Commission has ensured that support for Member States is provided for the implementation of the cost-optimal methodology through a help-desk for the cost optimal methodology.

According to the Regulation, Member States should define a minimum of 9 reference buildings – one for new and two for existing buildings, for single-family, multi-family and office buildings. Ideally, reference buildings are defined based on the characteristics of the existing building stock.

The Guidelines support the Member States to:

  • Define reference buildings;
  • Define energy efficiency measures;
  • Assess the final and primary energy needs of the reference buildings and the impact of improvement measures; and
  • Calculate the cost of the energy efficiency measures by applying the principles of the Comparative Methodology Framework.


Early experience

The Concerted Action EPBD conducted a study on experiences and challenges of setting cost optimal levels for energy performance requirements. The results were used by the European Commission. The report is available at BUILD UP website as EPBD Concerted Action Report on Cost-optimal levels.

Early experiences of cost-optimal calculations and analyses in various Member States show that using the cost-optimal procedure provided awareness about the importance of economic criteria. Results from calculations show that switching to a societal perspective asks for more efficient buildings, though with only small differences when compared with a private investor perspective. The first reports delivered to the European Commission are available at European Commission’s pages for energy efficiency and at BUILD UP publications.

Initial results show that, in some Member States, existing requirements are below cost-optimal levels. However, in a number of Member States minimum requirements are already more demanding than the cost-optimal level calculated by the Recast EPBD.


BUILD UP Community

Further information on cost-optimal methodology can be found on the BUILD UP Community ‘Cost-optimal energy performance.