One of the requirements of the Energy Performance of Buildings Directive (EPBD) for Member States is to define minimum requirements for new buildings and major renovations. This measure makes an important contribution to the climate objectives through a reduction of greenhouse gas emissions resulting from the heating and cooling of buildings. Below is an overview of the state of affairs and the latest developments.

What is the Energy Performance Regulation (EPB)?

EPB is the instrument used to realise a higher energy efficiency in new buildings or renovations equivalent to new buildings and lower greenhouse gas emissions as a result. The basic principle is to push for more energy efficiency by imposing minimum requirements in a design phase. For this purpose, Member States have set minimum levels of energy performance that a building must achieve. In addition, each Member State has developed a methodology to objectively test whether or not a design meets the minimum requirements. The fact that each Member State must have minimum requirements for buildings is laid down in the Energy Performance of Buildings Directive (EPBD). The height of the minimum performance requirements is determined by Member States based on the definition of nearly-zero energy buildings (NZEB). In addition to the requirements for the overall energy performance of a building, additional boundary conditions are defined in the form of minimum values for insulation, etc. The requirements differ for residential and non-residential buildings. For non-residential buildings, a further distinction is made between the requirements per intended function.

Links to the minimum requirements per region:

Impact of the EPBD revision

The Directive includes a number of requirements for optimisation of the EPB methodology and draws attention to the integration of requirements for technical building systems and smart technology. Requirements for technical installations lead to change correction factors, which are applied in EPB. The references to smart technology are more indirect; the Directive includes a number of requirements around providing infrastructure for electromobility, monitoring the consumption of technical building systems and a Smart Readiness Indicator (SRI). The Directive seeks to strengthen the link between the EPB standards and the EPB calculation methodology by stressing the importance of their application. In addition, Member States are required to define their calculation methodology according to Annex A of the ISO 52000-1, 52003-1, 52010-1, 52016-1 and 52018-1 standards. The Directive also requires that the numerical indicator of a building's primary energy consumption in kWh/m2 per year is used for determination of the energy performance of both existing and new buildings.

For more information about the revision of the EPBD, click here.

Implementation in Belgium

The implementation of the minimum requirements of the Energy Performance of Buildings Directive (EPBD) is a regional responsibility in Belgium. This means that separate requirements have been defined for each region on the basis of the determined Nearly-Zero Energy (NZEB) level to be achieved for all buildings by 2050. The methodology for testing the requirements and the associated software are virtually the same in the three regions as they are developed jointly. The final indicator for expressing energy performance (the output of the calculation) is different for each region. For example, in the Flemish Region it is referred to as E-peil, in the Walloon Region as Ew level in addition to a numerical indicator expressed in kWh/m2/year and in the Brussels-Capital Region as NEV (net energy demand for heating) and PEV (primary energy consumption) expressed in kWh/m².year. The Regions work together through a consultation platform and are supported by the EPB consortium.

Design of the methodology

In order to objectively assess whether a (design of a) building meets minimum requirements, it is necessary to establish a methodology to calculate the energy performance of the building. The difficulty lies in the many different types of buildings for which this method must be usable. The methodology also has to be representative at a single measurement point, while the energy consumption in a building can change during its lifetime. There are therefore a number of considerations of great importance in the development of the methodology:

  • The methodology must be sufficiently precise to ensure that all the energy efficiency achieved, both with the building and the products used, can be taken into account. Otherwise more efforts need to be made to achieve the required minimum level of performance.
  • The methodology must be sufficiently flexible in terms of the choice of building techniques and building technologies to guarantee as much choice as possible in the design process. This is to prevent that the costs of the design increase as a result of a monopoly.
  • The methodology shall be sufficiently representative of the final energy consumption of a building. This is to ensure that less energy consumption and thus a reduction in CO2 emissions is actually achieved.
  • The energy consumption resulting from the use of the building, despite the large impact on the final energy bill, cannot be included in the calculation. The reason is that usage changes regularly during the life of a building (see Figure 1).

Figure 1: Impression factors with an impact on the energy consumption during the life of a residential building

Development of the methodology

The development of the energy performance methodology is a continuous process; better software capabilities, innovative building products and improvements in the energy quality of buildings provide opportunities to create an even more representative methodology. This need is reinforced by the fact that the energy performance of buildings is generally improving; where more than 10 years ago heat loss had the greatest impact on the energy consumption of the building, other factors such as heat gains from the sun are of greater influence in buildings with a high energy performance. This requires a different approach in the calculation. The knowledge development around the design of the energy performance methodology takes place in different ways. In Belgium, the development of knowledge regarding the design of the methodology is initiated by the regional administrations. They are collaborating with the EPB-Consortium, which was set up for this purpose in 2015 under the leadership of the Belgian Building Research Institute (BBRI), and several stakeholders. Within Europe, knowledge development is built up through the design of European EPB standards, which were initially developed in 2007 at the request of the European Commission.

It takes a village..

The design of the methodology to determine the energy performance of a building requires the union of different types of expertise; knowledge on the input requirements and the final layout of the calculation, the design of the software, the layout of the regulations and related policy processes and the scientific determination of (standardized) parameters to be used is necessary. The knowledge holders of the different types of expertise generally differ (see figure 2):

  • Reporting

In Belgium, the knowledge holders regarding the reporting phase are generally the ‘EPB rapporteurs’  (and architects are active as ‘EPB rapporteurs’). They carry out the calculation to determine the energy performance of a building. To realise this they need a good understanding of the design of the building that is to be realised and the way in which the building characteristics need be implemented in the methodology.

  • Software

Given the complexity of the methodology, a software is used to perform the final calculation. The conversion of the set of formulas and parameters, of which the methodology consists, is carried out by software developers. They need a good understanding of what exactly has to be calculated and how this can be presented to the ‘EPB rapporteur’ in the most user-friendly way possible.

  • Regulations

Since the EPR is an official review instrument, the method of calculation needs to be described in legislation. In Belgium, this consists of separate regulations per region. In addition, an enforcement framework has been drawn up to determine what should happen if a building does not meet the requirements and who is responsible for it. This requires expertise on the policy processes for the amendment and development of regulations.

  • Research

Research is carried out to determine how best to design the calculation method. This is aimed at determining the formulas on the one hand and at the parameters that can be used on the other hand. These parameters are in a way a derivative of the behavior of a building technology in a building to the "one-off moment" for which the energy performance is determined. Expertise in this field is spread among various parties, such as the knowledge institutes and the industry.

What appears to be a good proposal for the development of the methodology from the viewpoint of one expertise can make the work for another expertise very complex. The development process is therefore a constant search for consensus.

Figure 2: Schematic interpretation of the different phases in the development of energy performance methodologies

Current developments

In light of the fact that new buildings are becoming more and more energy efficient and therefore require a more accurate methodology, discussions have started on what the methodology should look like in the future. One of the pending questions is whether the current methodology and software will still be able to meet the future demand. In 2017, the three regions therefore decided to launch EPB 2.0; a joint project to see how a revision of the EPB policy framework could take shape and how a number of common complaints regarding the methodology could be resolved. These have resulted in following point of discussion (among others):

  • Reducing the gap between real and theoretical consumption

To be able to make a good estimate of the actual realised reduction in CO2 emissions via EPB, the accuracy of the determination of the energy performance of a building is important. It has been found that in practice the actual energy consumption and the calculated energy performance can be far apart. The discussion examines possibilities to achieve a more accurate end result without making the methodology itself too complex.

  •  Simplification

The amount of data that needs to be collected for a calculation of the energy performance of a building can be time-consuming. This is dependent on the number of parameters that need to be filled in and the availability of the required data.  This requires a trade-off between the desired accuracy of the methodology, the possibilities to automate the calculation of certain parameters and the impact on the final energy performance. The discussion looks at ways in which the input can be made as simple as possible while minimising the risk of errors without losing the accuracy of the end result.

  • Accelerated integration of innovation

A form of simplification for manufacturers and suppliers of building products and technologies is acceleration of the procedure to valorise innovations in the methodology. At the moment this takes a few years, while within that time often several new innovations have been brought to the market. For valorisation, however, it is currently necessary to adjust parameters and thus adapt the regulations. A change in the regulations also means the provision of training. This takes time. The discussion and associated research therefore focuses (among other things) on finding ways in which the integration time can be shortened without having to change the regulations too often.

  • Comfort and health

An important precondition for the realisation of high-quality, energy-efficient buildings is a comfortable and healthy indoor climate. This involves for instance regularly changing air in a room; for example, if an office does not have sufficient ventilation, it can cause problems with concentration. In addition to striving for the optimum reduction of heat loss, it is therefore just as important to strive for good air quality. The discussion around this focuses, among other things, on the integration possibilities of smart technology and adapting specific parts of the methodology.

  • Enforcement

Testing buildings for their energy performance means that it is necessary to determine consequences in case a building does not meet the requirements. In addition it has to be determined who is held accountable. In the current design of the methodology, EPB reporter has the main (final) responsibility for the quality of the EPB report. Concretely, this means that they can be fined if there is an error in this report; even if the error is beyond their control. The discussion therefore looks at how best to design the enforcement in a way that ensures that the report is accurate, but also remains doable.

Within the joint EPB project of 2017, the Flemish Region took the responsibility for the review of the policy framework. The Walloon Region took responsibility for the revision of the software. In 2019, it was decided to focus the review on exploring the possibilities for simplification of the policy framework. In addition a solution is being sought to realise an accelerated integration of innovation in the methdology. The aim is to simplify the procedure for integrating new products into the methodology for manufacturers and suppliers.

Role of Agoria

With their knowledge on building technology, Agoria tries to contribute to the EPB discussions regarding input parameters and the associated data for building technology products. Agoria is therefore active as a stakeholder in the ongoing EPB discussions and also conducts its own studies. For example, in 2018 Agoria developed a position to argue for further optimisation of the methodology. A study aimed at developing options for integrating the hourly method based on the EN ISO 52016-1 standard was completed in 2019. Agoria gave a presentation on the intermediate results during the study day 'EPB/EPC 2.0 and innovation' on 24 June 2019.