Advancing Energy Efficient Buildings in the Western Balkans

27-01-2026 | Tags: Clean Energy

As part of WBIF’s ongoing efforts to strengthen sustainable energy development in the Western Balkans through the Regional Energy Efficiency Programme (REEP), Communications Consultant Jelena Mikić (KfW) interviewed Dipl.-Ing. Heike Erhorn‑Kluttig of the Fraunhofer Institute for Building Physics (IBP). A leading expert who heads the institute’s “Buildings – Districts – Cities” working group, she shared her insights on Nearly Zero‑Energy Buildings (NZEB), Plus Energy Buildings, and the opportunities these technologies present for the region. Fraunhofer IBP is one of Europe’s most respected institutions in building physics, known for research, testing and demonstration projects that support efficient, climate‑friendly construction.

KfW: In simple terms, what exactly is a Nearly Zero‑Energy Building, and how does it differ from a regular building?

Heike Erhorn-Kluttig: A Nearly Zero‑Energy Building is a building with an extremely low energy demand that is covered by renewable energy sources. It typically combines a highly insulated building envelope, high‑performance windows, and efficient building services that make use of solar, geothermal, or ambient energy through technologies like heat pumps. Because these buildings need so little energy and rely heavily on renewables, they have a significantly smaller environmental footprint than conventional buildings. In the EU, Nearly Zero‑Energy Buildings have been the minimum standard for new public buildings since 2019 and for all new buildings since 2021. Each Member State defines the detailed criteria according to its climate and building traditions.

What are the most critical technical challenges when applying NZEB standards to existing buildings compared to new ones?

Most technologies used in new construction can also be applied in existing buildings, but the challenges are usually greater. Triple‑glazed windows, for instance, can be retrofitted, and adding external insulation is often straightforward. The difficulty comes in minimising thermal bridges at joints between walls, windows and roofs, which is much harder in older structures. Ventilation systems also pose a challenge because existing buildings often have limited ceiling heights. Switching to low‑temperature heating systems like heat pumps may require larger radiators or improved insulation to maintain indoor comfort. So, while the technology exists, adapting it to existing buildings often demands more careful planning and customised solutions.

How can buildings produce more energy than they consume? What does this mean for energy bills and environmental impact?

‘Plus Energy Buildings’ combine extremely low energy demand with substantial on‑site energy generation, usually through photovoltaic systems. Over the course of a year, they produce more electricity than they consume. In summer, they feed surplus electricity into the grid, and during other periods they draw electricity back when needed, effectively treating the grid as a temporary storage system. However, these buildings are not necessarily “plus energy cost” buildings, because the remuneration for electricity fed into the grid is generally lower than the price of electricity purchased from it. From an environmental perspective, though, they perform very well. While there is a slight increase in energy use in producing materials like thicker insulation to eventual demolition, the operational savings outweigh the additional energy. Many studies have confirmed this.

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“Cost‑optimal studies show NZEBs have the lowest lifecycle cost despite higher initial investment.”

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What are the biggest barriers preventing widespread adoption of NZEB standards in the Western Balkans?

The main obstacles include the cost gap between NZEBs and today’s standard buildings, as well as limited experience with key technologies such as geothermal heat pumps, photovoltaic systems, and smart control strategies. We also see a need for more training for planners and artisans to ensure that these systems are designed and installed correctly. Regulations play a significant role. Stricter building requirements, coupled with incentive programmes, would encourage wider adoption. It is also essential that feeding photovoltaic electricity into the grid is allowed and fairly remunerated. Pilot projects can help immensely by demonstrating that these buildings work well in practice and do not differ in comfort or appearance from conventional ones.

Why is it important for Western Balkan countries to adopt these standards now, especially considering economic and energy challenges?

Reducing the environmental impact of buildings is essential for mitigating climate change, and this applies everywhere, including the Western Balkans. Reducing dependence on fossil fuels is another critical factor, given the region’s energy vulnerabilities. In addition to lowering emissions, these buildings also offer improved indoor comfort, which directly benefits occupants.

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“Reducing the environmental impact of buildings is essential, and decreasing dependence on fossil fuels is critical for the region’s energy security.”

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How can energy‑efficient building projects create local jobs and economic opportunities in the region?

We see similar discussions across EU Member States. Higher standards for energy‑efficient buildings generate more work for architectural and engineering firms as well as skilled artisans. Innovations in high‑performance building technologies can also become export opportunities. As expertise grows in the Western Balkans, professionals in this field will also find it easier to work across EU Member States, increasing mobility and career prospects.

What does the future hold for energy‑efficient construction in Europe?

With the revised Energy Performance of Buildings Directive, Member States must further tighten minimum energy standards and move toward zero‑emission buildings that no longer rely on on‑site fossil fuels, such as oil or gas boilers. As operational energy use declines, we must pay closer attention to the energy and emissions associated with producing construction materials and building technologies. For this reason, the life‑cycle global warming potential will need to be disclosed in the building’s energy performance certificate. When Western Balkan countries join the EU or align their rules with this directive, they will follow the same requirements.

How does Fraunhofer IBP contribute to the EU Green Agenda?

Our experts support the EU, Germany, German regions and cities, as well as countries such as Montenegro and Albania and institutions like KfW Bank. We work on developing policies, assessing their impact, and designing and testing energy‑efficient building technologies. We also support communication of targets, impacts and results to the public. Fraunhofer participates in several initiatives aimed at transforming buildings, transport and energy use to achieve climate neutrality in the future.

How do you calculate the return on investment for NZEB projects? Can you share examples from Germany?

In Germany, Nearly Zero‑Energy Buildings are already the minimum standard for new buildings. A cost‑optimal study for the European Commission has shown that this performance level results in the lowest overall lifecycle cost. Even though upfront costs are higher, operational savings over time ensure a positive return on investment. Cost‑effectiveness improves further when buildings exceed the minimum requirements and benefit from long‑standing German support schemes such as low‑interest loans and grants for efficient construction and renovation. These are provided by the state‑owned KfW Bank through local banks.

Which policy and regulatory frameworks in the Western Balkans require donor support?

In countries where cost‑optimal calculations have not yet been conducted, donor support can help determine which efficiency levels are economically sound. This feeds directly into updating building regulations. Energy performance calculations and energy performance certificates need to follow the requirements of the Energy Performance of Buildings Directive, including a comprehensive calculation method and, likely in future, a simplified life‑cycle assessment. Training for planners, EPC issuers and artisans will be necessary, and pilot projects can support the overall transition.

What are the key risk factors for NZEB projects, and how can they be mitigated?

The technical risks are relatively limited, as the concepts have been successfully implemented in many countries. The real risks arise when quality control is inadequate during planning and construction. In pilot projects, costs may also be higher when using new or unfamiliar technologies because of perceived implementation risks. In such cases, financial support can make a significant difference by reducing investor hesitation.