Dr Andreas Hermelink studied Business Economics and Civil Engineering and holds a PhD in Sustainability Evaluation of Buildings. Dr Hermelink is a leading expert on decarbonisation of the building sector with 25 years of professional experience. He led numerous key projects for public sector clients, including a GIS-based building typology for Hamburg, or the technical assistance to the European Commission in their EPBD impact assessment leading to the revised 2024 edition, but also for industry and commercial sector clients like Green Building Guidelines for McDonald’s, or innovative approaches for financing ESCO-driven energy renovations of buildings for an international development bank.
BUILD UP (BUP): Can you explain what the EU Building Stock Observatory is, and what its objectives are in relation to the EU's decarbonisation and energy efficiency targets?
ANDREAS HERMELINK (AH): The EU Building Stock Observatory, also called the BSO, is the central database dedicated to the EU’s building stock. It is directly operated by the European Commission. Via its user-friendly web-interface, the BSO is accessible by everyone, thereby meeting different user needs by single-page country factsheets, or by its comprehensive, interactive graphical user-interface (called the database), or even by providing the option to download the full dataset.
Ultimately, the key objective of the BSO is to support the implementation of the renovation wave and Zero Emission Buildings by providing data which allow for the monitoring of the status and progress of the building stock’s decarbonisation, energy efficiency, and alleviation of energy poverty.
BUP: What is your role within the EU Building Stock Observatory, and how do you contribute to achieving its objectives?
AH: I am the leader of the team supporting the European Commission in their effort to significantly upgrade the user experience, the database and indicator structure, the data, and communication around the BSO under a service contract with CINEA. As such, I am CINEA’s and the European Commission’s key contact for all strategic, and many operative, aspects of the project. The great colleagues at CINEA and the European Commission in charge of the BSO and I also act as main spokespersons of the BSO.
The major milestone of the project has been the very successful relaunch of the BSO in March 2024. Obviously, this has been a joint achievement of the great team I’m proud to have convened for this lighthouse project. It consists of BPIE, Danish Energy Agency, EURAC, Technical University Vienna and a crew of my Guidehouse colleagues from both the US and Europe.
Building stock data is key to improve policies and to monitor their impact. Many of the stakeholders who would like to have these data are in the position to also contribute data to the BSO or to support the improvement of data. Collaboration is my credo, and this is why I’m pushing hard to build as many bridges as possible to and between stakeholders who really should collaborate for the sake of useful data in the BSO. So far this has been very successful. Also, thanks to the European Commission’s and CINEA’s support, we’ve built bridges to the Concerted Actions EPBD and EED, to the European Environment Agency EEA, and to the European Commission’s Joint Research Centre JRC. I’m very grateful for all the support they have provided so far. I have also developed the concept of trusted partners - third parties, like manufacturer associations, who would like to take the opportunity to periodically provide high-quality data to the EU Building Stock Observatory. To any reader who belongs to such potential trusted partner: please contact me!
BUP: What types of data are collected by the Observatory, and how is this data gathered?
AH: The general idea of the BSO is to provide information related to the size of the building stock and its energy, environmental, financial, and social performance. Information is generally presented for the EU as a whole and individually for each EU Member State.
Indicator selection, e.g., floor area, in our project follows very strict rules. Although these rules may sound trivial, I’ve seen them being disregarded too often in these kinds of projects and then cause rather inefficient use of limited resources for data collection. An indicator must be relevant for the BSO’s objectives. Data belonging to an indicator must be collectable, and data must be consistent, which means at least bi-annual availability, and following a similar definition and approach for collection across Member States and years.
No field research is done due to the scope of the project. Yet, the whole team is involved in desk research in one way or another. Above mentioned rules and a clear future-proof logic for how to organise the different indicators have been elaborated by BPIE. They also lead the dissemination activities, where we always encourage participants to verify the BSO data and provide hints for improvement where possible.
EURAC is the provider of the very hard to determine, yet everybody wants to know very granular building stock size data we now have in the BSO. This is based on extensive experience from previous projects and involves massive statistical analyses. TU Vienna supports with expert advice on simulation of data gaps. Danish Energy Agency enables the very important direct access to the Concerted Action EPBD, a longstanding forum of EU Member States’ representatives who are responsible for EPBD implementation. This is because Member States are not just a main user of the BSO, but due to the new EPBD and EED provisions on the BSO, Member States will also evolve into the BSO’s main data provider. Last, but not least, my Guidehouse colleagues from the US have redesigned the user interface and the database structure, while my European team digests and translates most relevant Eurostat, EEA and JRC data into ‘fit for BSO’ datasets.
BUP: Is there a need to improve the quality of the data or to expand the sample of buildings from which this data is collected? What are the biggest challenges in this regard?
AH: There is a purely economically driven need to significantly improve the quality of data we have about buildings, which we ultimately use as input to the BSO. I feel that generally there is a misunderstanding about the real costs and benefits of good quality data about buildings. Although having dealt with collecting building data for more than two decades, there are still way too many occasions where even information that you would expect to be most basic for proper decision making, like floor area, is either not existing, or not accessible, or too fragmented or incomplete, or based on approaches ignoring proper statistics, or simply too poorly defined or documented to allow for proper validity and consistency checks. These are all symptoms of so far not having had an overall strategy in place, that would result in timely provision of good quality information, which stakeholders and especially policy makers should have for proper decision making. This absence of a systematic data collection strategy leads to inconsistent bits and pieces of information, which I’ve often seen trigger follow up projects trying to make sense out of it.
There certainly is a significant potential for improving the efficiency and effectiveness of data collection, when 27 Member States independently develop 27 more or less similar approaches for collecting data on basically the same indicators. Yet even higher costs result from not having proper data. Improper or inconsistent data leads to higher than necessary uncertainty in policy and decision making about buildings, which in the EU context means decisions about hundreds of billions of Euros. Better data allowing better decisions could save billions of Euros in the decarbonisation of buildings, e.g., when it is about optimal spending of financial support. Don’t get me wrong, the data we currently have already allows much better decisions than not having any data. Yet, I’m convinced we are still far away from an equilibrium, where an additional investment in better building data will not yield a net societal benefit anymore.
Fortunately, this situation is tackled by significant improvements in the revised EPBD relative to reporting on building stock related data. I’m very confident Member States and the European Commission will take this opportunity to align on a data collection strategy and implementation that will allow a much more cost-effective use of resources overall through better informed decision making. Ultimately this will also benefit the quality of data in the BSO.
BUP: At the European policy level, what is being done to expand and enhance the quality of the database?
AH: The revised EPBD has paved the way for a completely new era of the EU Building Stock Observatory. New provisions directly addressing the BSO open the door to much better and much better-aligned data within and across Member States and for getting them into the BSO. When the first BSO started in 2016, it was a ‘nice to have’ service kindly provided by the European Commission. Today, the revised EPBD has turned it into the mandatory reporting platform for both Member States and the European Commission.
First, Article 22 of the revised EPBD requires Member States to set up national databases for the energy performance of buildings, allowing, e.g., the collection of information from energy performance certificates, inspections, smart readiness indicator, renovation passports, etc. However, the decisive provision in Article 22 requires that ‘At least once per year, Member States shall ensure the transfer of the information in the national database to the EU Building Stock Observatory.’ A harmonised approach for that transfer is ensured by common templates the European Commission must adopt, the first one being due already by 30 June 2025. The first recommendations for this template have been developed in the ongoing project I’m leading.
Second, Article 3 of the revised EPBD on National Building Renovation Plans requires the European Commission to ‘monitor annually the evolution of the energy performance of the Union building stock … and publish the information through the EU Building Stock Observatory.’
I also would like to stress the additional boost, the revised EED’s Article 6 on public buildings gives to the BSO, by encouraging that ‘Publicly available and accessible data about building stock characteristics, buildings renovation and energy performance may be aggregated by the EU Building Stock Observatory.’ In a nutshell, in just a few years Member States will be the main data providers to the EU Building Stock Observatory, which will significantly increase the resources used for meaningful data collection, and, when properly orchestrated, will turn the BSO into everybody’s go-to-platform for high-quality buildings data.
BUP: How can emerging technologies, such as digital twins, contribute to better monitoring and data quality?
AH: Such emerging technologies certainly offer a lot of potential for a more efficient, more consistent, and more timely collection of data. I’m lucky to be part of a big consultancy, where two years ago my colleagues in the US provided me in-depth insights into what is possible in terms of digital twins. Recently I received similar insights relative to AI or machine learning applied to big data sets. However, these tools will only unfold their full potential as part of a holistic strategy. Before talking about digital twins and the like, which is saying ‘C’, we shouldn’t forget to say ‘B’, which is the overall strategy for improving monitoring and data quality, which again should be preceded by saying ‘A’, the acknowledgement of the value of better data, which hopefully would free significantly more resources for proper data collection.
BUP: To what extent do differences in energy efficiency calculation methods across Member States hinder the development of a consistent database? How might the new EPBD guidance help address this issue?
AH: As pointed out above, the actual energy performance of buildings is just one out of many indicators the BSO should cover according to the revised EPBD. Yet it is one of the indicators receiving very high attention. This is also due to energy performance getting more and more important for a property’s value. Guidehouse is working a lot for market players who operate across borders, e.g., banks or real estate funds. These players would love to have comparable, transparent energy performance results for their assets across Europe. Yet, having the same calculation procedures in each EU Member State would be a long shot. We recently saw that in another project led by Guidehouse for the European Commission on how to calculate the energy performance of Zero Emission Buildings and future cost-optimality calculations. Some outputs of that project have been used by the European Commission as input to the new EPBD guidance you mention. I expect the new guidance will certainly improve alignment between Member State calculations, but it certainly won’t make them all the same. Many Member States have invested a lot of resources in developing their national calculation schemes. Now they wonder about the costs and benefits of making major changes to it for the sake of higher consistency. Utmost transparency of those calculations will help most, i.e. providing all necessary assumptions and inputs for those calculations, as this would allow translation into a common calculation scheme, allowing direct comparisons. EPBD Annex 1 already asks for it: ‘Member States shall describe their national calculation methodology on the basis of Annex A to the key European standards on the energy performance of buildings.’ If it turns out that the provision does not yet allow that translation, a solution should be developed as soon as possible, as it would activate those market forces, we’d like to see act in favour of energy efficiency improvements and decarbonisation across the European building stock.
