Einari Kisel, Targo Kalamees, Ergo Pikas, Innar Liiv, Endrik Arumägi | Photos: Maa-amet, TalTech

The biggest challenge of the Green Deal of the European Union, which is still not much talked about, is to renovate all the buildings that will remain by 2050. A study carried out a few years ago by the Department of Civil Engineering and Architecture of TalTech found that in Estonia this would mean renovating around 60% of today’s buildings (the rest are either at a good energy efficiency level or will be demolished by 2050) at a cost of around 25 billion euros. While currently around 1% of buildings in Estonia are renovated each year, to reach this target, the volume of renovation would have to at least quintuple in the peak year.

Today, the responsibility for renovating buildings lies largely with the building owners. At the same time, most of them lack the financial means, knowledge and will to undertake renovation, even though the return on such investments could be 3–5 years at the current energy prices, not to mention the increase in property value. Although the state has been supporting the renovation of apartment buildings and private houses through KredEx for many years, the vast majority of buildings (especially in rural areas and declining cities) are still not renovated. Most of the time, only basic repairs are done, only a few people dare to undertake a complete renovation. In many cases, building owners also do not provide the local government with information about the construction and renovation work that is being carried out.

The European Union’s strategy for the renovation wave envisages that in such a situation, local governments should become the driving force behind the whole renovation process. At present, municipalities only play the role of approvers, approving building and use permits. However, if municipalities can understand how to renovate buildings and even neighbourhoods in a comprehensive and rational way to make them energy efficient and climate neutral, they could also offer support to building owners in making decisions and arranging financing.

In moving towards climate neutrality, the potential of buildings to contribute should be analysed. There are situations where, for example, it is not possible to achieve an energy performance class A or B because of heritage protection restrictions. If, however, a building next to it or in the same area is renovated into an energy-plus building, for example with solar panels producing more energy than is consumed, then climate-neutrality targets can also be achieved across the district.

To enable local authorities to share such information with building owners, a comprehensive renovation strategy for neighbourhoods should be developed. Such a strategy would provide information on the energy efficiency and climate neutrality potential of a given area, the level of investments that should be made in each building and the renovation measures to be used.

The renovation strategy tool RESTO comes to the rescue

At the beginning of 2022, a pilot project was launched in cooperation with the City of Võru, FinEst Centre for Smart Cities, Department of Civil Engineering and Architecture of TalTech, and the Department of Software Science of TalTech to create a digital tool for local governments to prepare regional building renovation strategies. In the future, such a tool will help local governments to support building owners in the preparation and implementation of comprehensive renovation projects, to assess the scale and impact of investments in the joint renovation of buildings, and to help identify the best technical solutions for the specificities of individual buildings. The pilot project is called RESTO, after REnovation Strategy TOol, and is funded by the Ministry of Education and Research and the European Regional Development Fund.

The idea of the RESTO tool is to collect data on the buildings in the observed area from various databases (building registers, the Estonian digital twin created by the Land Board, registers related to heritage protection restrictions, etc.) and compare their energy performance with the best renovated buildings. Based on nearly 500 parameters, the model analyses around 6,000 renovation options for each building, and suggests how to renovate buildings in a given area to meet energy saving and emission reduction targets and ensure optimal costs for building owners, while not conflicting with building constraints. RESTO will also reduce the workload for planners and designers, jointly renovating buildings will make this matter more attractive for construction companies and ultimately reduces the costs and bureaucracy involved with renovating buildings.

In Võru, the aim is to test the functioning of the tool in the buildings of a residential quarter bordering Kreutzwaldi, Tartu, Vee, and Vabaduse Streets in the city centre, and to prepare a sample renovation project for an apartment building in a heritage protection area.

There are challenges ahead

The first year of the pilot project was spent checking the availability and quality of building data from various databases, developing calculation methodologies and negotiating building restrictions. As was expected, the data on buildings in the building register, for example, is often quite inaccurate and does not reflect the actual situation. In order to solve the problem, TalTech researchers, together with KredEx, have analysed the technical indicators of more than 400 buildings and developed a database of reference buildings, which can be used to assess the energy efficiency of similar buildings. Currently, TalTech is in the process of programming and further analysing computing methodologies. Solutions are also being sought in cooperation with ministries and other public authorities to enable the widest possible use of the model in Estonia and other countries in the future.

In parallel with the development of the model, Võru City Government selected a pilot building (Kreutzwaldi 2) in a historical area through a public competition, for which a demonstration project of comprehensive renovation will be prepared in order to achieve the best energy efficiency class without damaging the exterior appearance of the building. It took longer than planned to find a designer, but they have now been found and by spring, a sample documentation should be ready, which can be used as a basis for other owners of buildings in the heritage protection area to commission renovation projects.

The pilot project will run until June, but already in spring it should be possible to get the first answers about the Võru pilot area – how much would it cost to renovate the buildings in the pilot area to be energy-efficient and climate-neutral, how much would the energy costs be reduced as a result, what kind of work would have to be done in the buildings and related infrastructure, how cost-effective would the renovation be, how would the installation of solar panels on the roof affect the result, etc.? Figuratively speaking, Võru will be the first city in the world to receive a digital energy audit of a region as a result of the pilot project, which would currently take energy auditors several months to complete. With RESTO, it should be possible in the future to produce it in a few hours. Other Estonian cities have shown interest in a similar analysis.

RESTO has also generated a lot of new knowledge in the scientific context. In the course of the project, completely new calculation models for energy efficiency and cost-optimal renovation will be developed, which should be able to perform large-scale calculations even with less accurate input data. In order to propose a prototype, it must be possible to strike a balance between the desire of researchers to provide the most accurate calculation results and the desire of policy makers not to wait for databases to be organised and to receive recommendations for which direction to take. Despite the short duration of the project, the project team has set itself the target of producing at least five research articles in collaboration.