Newswise — Improving the energy performance of buildings is one of the most important measures for supporting the global collective effort to reduce CO2 emissions and energy costs.

A recent study by Estonian researchers has revealed a positive message for Estonia: the energy performance measures we have taken to date have largely been effective in ensuring sufficient progress towards achieving a carbon-neutral building stock by 2050. Estonia has been particularly successful in the renovation of apartment buildings, with a complete renovation funding scheme that could serve as a model for all of Europe. This was the conclusion reached by researchers Martin Thalfeldt, Juri Belikov, Jarek Kurnitski, Eduard Petlenkov, and Andrea Ferrantelli from Tallinn University of Technology in a research paper published in IEEE Access.

New scales will bring a change

However, this was not found to be the case for all buildings. ‘The one exception is single family houses of less than 220 m² (2,368 square feet), which are subject to less stringent energy performance requirements, and for which renovation grants are still offered on a relatively limited scale,’ noted Martin Thalfeldt, assistant professor in the research group on nearly zero-energy buildings. This means that if Estonia wants to reach the target, it will need to continue to gradually tighten the energy performance requirements for new buildings, and ensure that measures are in place to encourage the complete renovation of buildings. Single family houses, where there has currently been no significant progress made, need to be given greater attention.

At present, researchers believe that we have reached a point where the best energy performance class A is also the minimum requirement for new buildings, and there is no class on the energy performance scale to strive for in more ambitious projects. Fortunately, the latest amendments to the European Union’s Energy Performance of Buildings Directive call for the further development of energy performance scales for buildings. ‘The new scales should evenly cover the entire building stock, with zero-emission buildings at one end, and the 15% of poorest-performing buildings in the lowest energy performance class G, at the other. Our research allows these scales to be easily developed for Estonia, and to identify the part of the building stock that should be renovated as a matter of priority,’ Thalfeldt explained. Fellow member of the research team, Juri Belikov, stated that the most interesting part for him was the insignificant impact of COVID-19 on the results, which included comparison with the previous year, and after 2020. This issue is also explored separately in the paper.

In-depth analysis was made possible by the Register of Buildings

An analysis of this scale was made possible for the first time thanks to the extensive database of the Estonian Building Registry, even though the study only covered buildings for which an energy performance certificate has been issued.
The difficulty of obtaining information on existing buildings is a major problem, as the available data are often limited to total annual consumption.

‘Unfortunately, there are a lot of buildings in Estonia for which we do not have an overview of the energy consumption,’ admitted Thalfeldt, who added that their research was part of the DigiAudit pilot project of TalTech’s competence centre for smart cities. The objective of the project is to develop methods for the automatic evaluation of the energy use of buildings. The research enables the energy use of any building to be automatically evaluated in comparison with other buildings of the same type. If reliable information on buildings and continuously updated energy consumption data could be collected in a common database, the methods developed would allow for the automatic calculation of energy performance ratings, and the monitoring of progress towards energy performance targets.

Running account – how far are we from the target?

DigiAudit’s project partners include Estonia’s largest cities Tallinn and Tartu, both of which are not just aiming to achieve carbon-neutral building stock, but also to become climate-neutral cities by 2050. In addition, the campus buildings of TalTech are also participating in the project.

‘We are additionally in contact with the Estonian Ministry of Economic Affairs to ensure that the methods developed in the DigiAudit project will also be applied on a larger, national scale,’ stated Thalfeldt, who claimed that the longer-term goal is to achieve a so-called running account of progress towards the targets for improving the energy performance of the building stock.

An intriguing challenge

But where does the 2050 target come from? The European Green Deal was strengthened at the end of 2021, when the European Commission decided to undertake a major revision of the Energy Performance of Buildings Directive (EPBD). The aim was to speed up the renovation of buildings, reduce greenhouse gas emissions and energy consumption, and promote the use of renewable energy in buildings.

As a result, the European Union is introducing a new definition of a ‘zero-emission building’ (ZEB), applicable to new public buildings from 2027, and for all new buildings from 2030. Existing buildings are expected to be converted into zero-emission buildings to achieve carbon neutrality by 2050 at the latest. This will require around a 2% yearly deep renovation rate, and a reliable evaluation of the energy performance of buildings is needed to develop measures to maintain an adequate pace of progress.

Key findings of the research

The most important result of the work conducted by the Estonian research team, which will help to monitor the decarbonisation of the Estonian building stock by 2050, can be summarised as follows: the researchers evaluated, by building type, how the energy performance of buildings has changed over time, and how progress has been made towards carbon neutrality; and formulated proposals and recommendations for the development of new energy performance scales. On the practical side, the energy performance benchmarking tables can be immediately implemented by building type to evaluate the energy performance of individual buildings in comparison to other similar buildings.

The researchers investigated in detail the energy performance certificates uploaded to the Register of Buildings, including the creation of a more orderly dataset. In the third section, the results are presented in thematic subsections, which include, for example, the time trend of energy performance classes, the impact of renovation incentives, benchmarking tables, and correlations with construction year and heated area.

As a natural extension of the study, new energy performance scales are planned to be developed for Estonia in line with the recently published recommendations by the European Commission. Furthermore, it is possible to identify the part of the building stock that needs to be renovated as a matter of priority, in order to leave only a negligible proportion of buildings in energy performance class G by 2030.

Leading academics and policy experts will discuss how buildings can be an important element in reaching the goals of European strategies such as the Green Deal and Fit for 55 through renovation wave, Energy Performance of Buildings Directive (EPBD) revision, New European Bauhaus, Construct Product Regulation (CPR) revision and REPowerEU. The seminar specifically focuses on research needs and research-based solutions, including people-centric and resilience aspects, ideally addressed at – along with improving – energy performance and indoor climate, renewable energy use, and the energy flexibility of buildings. These solutions should support the efficiency-first principle, but also have to consider many new elements when implementing the existing building stock’s transition towards zero-emission buildings.

Journal Link: IEEE Access