Innovative EPCs features in Greece: testing results and replication potential

The focus of the Horizon 2020 project X-tendo is the further development of energy performance certificate (EPCs) schemes in EU Member States. After analysing the theoretical background, the project focused on testing its innovative features in concrete implementation projects. This series of blog post will help summarise the testing in each of the X-tendo 9 countries to understand the practical viability and the challenges in the implementation of the developed ideas and materials.

Depending on the feature, the X-tendo partners performed different types of tests: In-building tests apply the feature materials on concrete buildings, user tests consist of understanding the user perception related to the developed materials and ideas, system tests intend to understand the application of feature ideas and materials in related systems like EPC database systems.

Features and buildings tested in Greece

In Greece, the X-tendo’s partner CRES, the Hellenic National Energy Centre for Energy Efficiency and Renewable Energy Sources, a public entity supervised by the Ministry for Environment and Energy tested four features to enhance current energy performance certificates: smart readiness, comfort, EPC databases and building logbook.

The features were tested on various buildings: smart readiness and comfort  features on apartments in multi-family buildings and offices,. For the EPC database, Greece performed system tests and for the logbook, both system and user tests.

Summary of results from the testing

Smart Readiness (SRI)

CRES studied four buildings to test the Smart readiness features: 2 office buildings and 2 apartments. The test consisted of on-site visits and walk through audits, followed by a gathering of the required data of the buildings and a collection of information on the installed technical systems for the assessment of the SRI with the use of the tool.

The results from the testing show that the SRI tool is easy to use and rather easy to complete, but some knowledge about the systems, technologies, efficiencies is required. As for the time and extra cost, they were respectively around 2.5 hours per building / apartment for data collection, assessor evaluation and calculation and costed extra 80 EUR.


The steps for the in-building tests of this feature were generally the same in all countries:

  1. Administration / data collection – including gathering of building data, distribution of tasks and establish a testing strategy
  2. Measurements – carrying out the measurements in the buildings
  3. Surveys – conduct the foreseen surveys amongst the building users
  4. Checklists – perform inspections and observations in on-site visits
  5. Rating calculation – calculate the comfort indicators using the provided spreadsheets.

In Greece tests have been conducted in four buildings: two office buildings and two apartments. On-site visits and walk through audits were carried out combined with the testing of the SRI. The measuring equipment was used to record indoor temperature, relative humidity, CO2 concentration as well as ambient temperature. All collected information was used in the provided spreadsheets to calculate the comfort ratings.

Results show that the comfort feature methodology and tool developed are well defined and easy to use. Users’ perception about comfort differs from the calculated one and assessors should be trained to effectively use the tool. The integration of the indicator in the national EPCs would require policy support and decisions on assessors’ fees and possibly setting it as a mandatory requirement in relative national incentive programmes.

EPC Databases

Greece ran software on the EPC database to identify outlier EPCs, i.e. EPCs that differed significantly from the bulk of the EPCs of similar buildings stored in the database. The similar buildings concept was implemented by defining a set of building clusters that contained buildings similar in age, renovation, location and use.

Between the challenges encountered by Greece was defining clusters with detailed enough definition for the buildings in each cluster to be similar from an energy performance point of view, while containing enough buildings to give statistically significant results. This was especially true for large buildings (e.g., hotels or hospitals) in non-urban areas.

The main advantages instead are thatthe s/w is able to provide the user (building owner, energy expert, EPC assessor) with information comparing the building to similar buildings, useful for data quality control and preventing mistakes, as well as informing the building owner about the performance of specific building components.

Building logbook

In Greece, a logbook messaging protocol was designed to describe the data exchange with the EPC database and a prototype of an online logbook management system was developed.

The corresponding web service (logbook-ws) and the data provider application, needed for communication with the Greek EPC registry ( were both implemented. Considering the technical and practical viability of the proposed logbook design and taking into consideration the time, cost implications, integration with existing systems, access to data and data privacy issues, CRES described the implementation of these functions as ‘neither easy nor difficult’.

The major challenges were in the design of the protocol and the software to make them compatible with external applications of logbook data providers (e.g. Land Registry, Tax Dept., etc.). The main advantages of the features were instead the integration of building information into a central system owned and with the potential to be directly operated by the building owners themselves.

The major costs were in the software design and development, and the collaborative work of the various stakeholders, but these costs can be minimised using simple and widely adopted IT technologies (e.g. RESTful / JSON).

As per the user testing, the objective was to understand and document the effect of the logbook design elements on the work of stakeholders and administrators. CRES engaged user groups to obtain input to the proposed design elements of logbook features, and the design of the standard web-service providing interoperability between a building logbook and an EPC registry. The respondents appeared to understand the features well, and thought that the logbook would be useful for building owners and would facilitate interoperability between public sector IT applications. The conclusion is that a central building logbook would be beneficial, and it should thus be implemented by a governmental agency, and extensible by others. There is need for relevant legislation to support this.

Replication potential and conclusions

According to the EPBD recast, the SRI will be required for large non-residential buildings as of 2026 and Member States shall set up national databases for energy performance certificates of buildings, which also allow to gather data related to building renovation passports, in addition to the smart readiness indicators. Considering the legislative EU requirements and the X-tendo testing in Greece, a reduction of time needed, and costs incurred for the assessment of the Smart Readiness Indicator seems the most important next step in the feature development. Furthermore, the user-friendliness of the tool could be improved by adding for example a slider to the calculation spreadsheet for selecting the share of the functionality level. In addition, special attention should be given to the safety issues (i.e. data privacy and cybersecurity risks), that could limit the implementation of the SRI.

As for the comfort, the developed tool and guidelines were perceived as well-established and felt easy to use and relevant to the user when assessing the energy performance of a building. Still, a glossary of terms as well as references to documents could be provided in the tool itself to increase user-friendliness. Also, at the national policy level, the indoor comfort aspects should receive more attention.

For EPC databases and building logbooks, different steps can be taken to ease their implementation and effectiveness:

  • Verification checks should be implemented in the EPC calculations and EPC registry software
  • A continuously updated statistical analysis of the EPC energy efficiency data can be very useful in the data quality control of the EPC registry
  • Standardization of a data exchange format for the EPC data would greatly facilitate the relevant software development
  • Logbook as an aggregator of data supplied from (stored into) various building related databases, seems to be the preferred architecture
  • A standard but open to revisions Logbook Messaging Protocol is imperative in bridging between the logbook various data suppliers
  • A public entity should be in the centre of the logbook implementing efforts, facilitating and coordinating third party software developers.

The above recommendations also fit the EU objectives of defining a standard EU data exchange format for the EPC data and to reach interoperability between building related databases.

For more information on testing and recommendations, read the full report Implementation guidelines and replicability potential of the innovative features for the next generation EPCs here


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