site.btaExpert: Corrosion Threatens Bulgaria's Building Stock as Poor Conditions Persist, Refurbishments Merely Hide the Flaws

The impact of climate change, particularly rising temperatures and increased humidity, on the structural integrity of multi-family residential buildings in Bulgaria due to corrosion, remains unknown. Even if the effect of climate change is disregarded, corrosion is already a reality, and the widespread retrofitting projects merely hide the damage, Marin Gergov, Chair of the Management Board of the Chamber of Engineers in Investment Design (CEID), told BTA's Ekaterina Toteva and Valeria Dimitrova in an interview.

Gergov said the response strategies of State and local authorities to natural disasters, like earthquakes, are also unclear because Bulgaria does not have a unified registry of technical passports. Furthermore, less than 10% of buildings in the country have a technical passport, meaning no one knows what their true structural condition is.

He was approached by BTA to comment a recent study by the Joint Research Centre (JRC) of the European Commission on the impact of climate change on the corrosion of the European reinforced concrete building stock. The study reveals the effects of climate change-induced corrosion on buildings in European countries, including Bulgaria.

The study predicts that under a severe climate change scenario, with a projected temperature increase of 3C by the year 2100, Bulgaria could face total repair costs due to corrosion amounting to EUR 11 billion. This would require repairs for 99% of the roughly 383,174 buildings surveyed nationwide.

Technical passports

The Long-Term National Strategy to Support the Renovation of the National Building Stock of Residential and Non-Residential Buildings by 2050 shows that just over 2,200 residential buildings have technical passports. This information, published on the website of the Ministry of Regional Development and Public Works, notes that the buildings with these documents have been included in various retrofitting programmes aimed at improving their energy efficiency. 

Reports indicate that the preparation of these passports often prioritizes the lowest price, due to which they are often of questionable accuracy and quality.

To make matters worse, technical passports are kept by the municipalities rather than in an integrated register, and are not always accessible. This results in a lack of reliable information on the structural condition of our housing, said Gergov. He also mentioned that cadastral data cannot provide this information, and one can only rely on statistics, which only offer general information about building types.

Corrosion, even without global warming

Gergov said that it is not required to wait for global warming and higher air humidity to recognize that the buildings in the country are structurally unsound. Exceptions include buildings with well-waterproofed facades that are kept at standard temperature and humidity levels. Most reinforced concrete multi-family homes belong in this category because their facade panels, except for the gable panels, are typically not load-bearing. This means that when rooms are heated, their interior walls are protected from corrosion, leaving only the gable walls at risk. In bathrooms and homes with leaks, however, corrosion has affected the structure of the walls.

Buildings in the central parts of major cities are in a fragile condition, said Gergov. These brick structures are also vulnerable to harsh weather and other factors. Many are over 70 years old, with deteriorating plaster, leaking gutters, or waterlogged foundations, and water has been damaging their load-bearing walls for a long time.

The absence of a register for technical passports prevents the State and municipalities from planning for potential natural disasters and emergencies. During a major earthquake, for example, urban downtown areas might become inaccessible to ambulances and heavy clearing equipment.

It is wrong that obtaining a technical passport, which is crucial for the State and municipalities, especially from a seismic standpoint, should be left to the buildings owners with no support from the State, Gergov said. At present, technical passports are either stored on paper in a town hall basement somewhere, or as a throwaway PDF file in a directory, making the information within them unusable for statistical purposes and planning by the State and municipalities, said Gergov.

He suggested that the best option for the State and municipalities is to develop a uniform register of technical passports. This register will contain entries for engineering and construction details, to be completed by experts. It would create a publicly accessible database on the structural condition of residential buildings in areas with a high risk of disasters and accidents.

Lipstick on a pig

Gergov argues that the process for retrofitting buildings in Bulgaria is flawed, as it mainly concentrates on thermal insulation for residential buildings and maybe also roof repairs. He noted that structurally, the buildings are in poor condition. Refurbishment hides the structural problems of the housing, as a proper evaluation of the condition, like the walls, cannot be done by an external inspection without affecting the insulation. Corrosion can only be confirmed at an advanced stage when rust spots appear on the walls.

He noted that the absence of specific guidelines in the relevant regulations for conducting assessments for technical passports means that professionals perform evaluations according to their own judgment. This is a concern for all of Europe, as European funding prioritizes reducing harmful emissions and energy costs, while overlooking the structural stability of buildings. Improperly installed insulation that allows air with external temperature and humidity to circulate behind it will inevitably lead to corrosion.

"This insulation conceals the condition of the walls from the experts. What this renovation program does is putting lipstick on a pig," Gergov said. As buildings continue to be in poor technical condition, they get retrofitted with thermal insulation without addressing other necessary refurbishments first.

This prompts the question of whether investing European taxpayers' money in thermal insulation is the best approach, he argues. "What these funds achieve is merely boost polystyrene production and could instead be used for meaningful refurbishment and extending building lifecycles, implementing cost-effective heating and cooling systems, and reducing water losses. [...] In most cases where insulation is installed, nobody knows the technical condition of the building. Everything is flawless on paper, in the technical documents." 

Also, the experts have assessed the structure's load-bearing capacity using older, less rigorous construction standards. If the evaluations were done using newer, stricter standards, the results would be significantly different, Gergov said.

When home owners see the cost and detailed scope of a proper detailed technical assessment of a building, which involves drilling into walls and other structural elements, they often go to another professional who offers a lower price and a more superficial evaluation. "A comprehensive building assessment is costly but delivers essential information, such as the ability to determine the level of earthquake resistance a building can endure," he added.

The challenge of establishing the actual state of buildings in Bulgaria is likely to last for many years. This issue will persist until land prices increase substantially, making it more cost-effective to demolish a building rather than carry out extensive renovations, Gergov believes.

The buildings in Bulgaria

The Long-Term National Strategy to Support the Renovation of the National Building Stock of Residential and Non-Residential Buildings by 2050 says that Bulgaria has 1,365,898 residential buildings that are inhabited year-round. Of these, 1,291,549 are single-family homes, and 66,865 are multi-family residential buildings.

As much as 34% of occupied residential buildings in Bulgaria were built before 1960, when there were no energy efficiency regulations. The bulk of existing residential buildings were built between 1960 and 1989, accounting for 52% of inhabited residential buildings and 60% of the usable area. It was during this period that the majority of prefab panel and reinforced concrete buildings came into being. 

Energy conservation requirements were introduced for the first time in this period, setting regulatory standards for heat transfer through building envelope components like external walls, floors, and roofs. 

Between 1990 and 1999, 7% of the occupied residential buildings were completed, accounting for 9% of the total usable area. After the year 2000, with the introduction of modern and stricter energy efficiency regulations, only 7% of residential buildings were completed, accounting for 13% of the total usable area.

The Strategy notes that a significant number of residential buildings, both single-family and multi-family, are in poor condition due to lack of maintenance and regular repairs. This deterioration poses a potential threat to the structural integrity and the effectiveness and sustainability of future energy efficiency measures.

The strategy's calculations indicate that the annual investment needed for energy efficiency measures in residential buildings is estimated at BGN 257,180,671 for 2021-2025, BGN 535,480,142 for 2026-2030, BGN 911,015,558 for 2031-2040, and BGN 1,007,003,984 for 2041-2050. There are many buildings with structural problems due to various factors.

To ensure their longevity, construction work is necessary, which can be quite expensive, as the Strategy indicates. These costs are unpredictable because they differ for each situation. It was concluded that the presence of such buildings should be considered when prioritizing target segments of the building stock.

Retrofitting funding

A total of 756 multi-family homes in 102 municipalities have been approved for retrofitting under procedure BG-RRP-4.023, Support for Sustainable Energy Renovation of the Residential Building Stock – Stage I, as part of the National Recovery and Resilience Plan, funded by the European Union. Measures to improve the energy efficiency of these buildings will receive funding equal to BGN 1,128,694,945.76.

Invitations have been prepared and sent to all approved buildings, with more than 150 contracts already signed. Several municipalities are in the process of public procurement to choose contractors, depending on available funding. The physical implementation of energy efficiency measures for these buildings is scheduled to start in early 2025.

Additionally, 282 multi-family residential buildings in 65 municipal and district administrations have been approved for renovation under procedure BG-RRP-4.024, Support for Sustainable Energy Renovation of the Residential Building Stock – Stage II, within the National Recovery and Resilience Plan. The total funding for this procedure amounts to BGN 282,470,400, including VAT. 

Efforts are underway to meet the regulatory deadlines for Stage II. This includes assessing project proposals, addressing objections, and ranking the buildings that have applied for the procedure.

The processes are facing challenges due to insufficient human resources allocated at the start of the 2023 investment for sustainable energy renovation of residential buildings. Efforts are underway to build administrative capacity.

The total amount of grants under the procedure Support for Sustainable Energy Renovation of the Residential Building Stock, including Reducing Energy Poverty by Reducing Energy Costs, within Operational Programme Development of Regions, is BGN 196.4 million. During the application period, 329 project proposals were submitted by eligible municipalities. 

The evaluation of these proposals should be completed by the end of the year, with contracts due to be signed at the beginning of next year. The projects are set to commence in the first quarter of 2025, necessitating a prompt contractor selection process.