Different EU approach to nZEB in the EU Member States
Buildings are significant consumers of energy and contributors to environmental pollution. In the European Union (EU), buildings account for 40% of energy consumption and36% of CO2 emissions. To address this, the EU has set new construction criteria aimed at reducing CO2 emissions by 80-95% by 2050. One key strategy is the promotion of nearly Zero-Energy Buildings (nZEB),which are designed to have very high-energy performance with nearly zero or very low energy requirements met significantly by renewable sources.
The concept of nearly Zero-Energy Building (nZEB) was introduced in the EPBD recast in 2010(EPBD/2010/31/EU). Article 2 of the recast directive establishes what a nZEB is: a building with “a very high energy performance with the nearly zero or very low amount of energy required covered to a very significant extent by energy from renewable sources, including energy from renewable sources produced on-site or nearby”.
Understanding nZEB variations in the EU
The nZEB is not defined in the same way in the EU member states. It has been defined as a legal obligation in Denmark, Sweden, Finland, the Czech Republic and Croatia. Most of the definitions include an energy indicator of primary energy use, and 13 of them include the obligation to cover a minimum share of energy demand from renewable sources. For 18 of the Member States, an Energy Class or Energy label equivalent to nZEB requirements is defined. For the half of the Member States, the required U-Values for walls, roofs, floors, windows and doors are also provided.
Most agreed points in nZEBs definitions are:
• Heating, domestic hot water (DHW), ventilation, and cooling are the main included energy uses. Auxiliary energy and lighting are taken into account in the majority of Member States, while several also include appliances and central services;
• Energy balance calculations are derived as the difference between primary energy demand and generated energy over a one-year period;
• Single building or building unit are the most frequent physical boundaries in energy performance calculations;
• Conditioned area is the most agreed upon choice in relation to normalisation factors;
• On-site generation is the most common RES option, but some Member States also consider external and nearby generation;
Different system boundaries and calculation methodologies cause a high variation within the described definitions. The level of energy efficiency, the inclusion of lighting and appliances, as well as the recommended renewables to be implemented vary across Member States. Based on the climatic zones defined in the European Commission Recommendation and on the REHVA journal (REHVA, 2015), Member States are grouped under one representative climatic zone.
The Mediterranean climate includes the lowest values of primary energy and the highest share of use of renewable energy sources, and the term nZEB could soon be replaced with the term 0EM - zero emission buildings to emphasise the potential for greater use of renewable energy.
EC nZEB recommendation level of energy performance (kWh/m²/y) per building type and climatic zone are presented in the following table:
nZEBs primary energy values for most Member States exceed the benchmarks recommended by the Commission in both residential and non-residential buildings. The front-runners are Belgium Flanders, and the Netherlands. nZEB requirements are currently 70% lower than the national minimum energy performance requirements in 2006 showing a consistent trend in increasing building energy efficiency and a gradual move towards a zero energy consumption. This was obtained progressively in all these Member States, where at least 3-4 legislative steps were introduced over the last 15 years.
The role of technology and occupant behavior
In relation to technologies, the nZEB target is reachable with a proper combination of highly efficient solutions to minimise the energy demand for building operation while supplying remaining demand to a large extend with renewables produced onsite (PV, solar thermal, wind power, heat pumps). Most implemented technologies in nZEBs are passive (sunshade, natural ventilation and lighting, thermal mass, night cooling), and active (mechanical ventilation with heat recovery, heat pumps or district heating, solar and PV panels), in combination with efficient lighting and appliances.
Nonetheless, a critical role, not yet fully addressed, is played by occupant's behavior (Honget al, 2016). By implementing educational programs, leveraging smart technologies, and offering incentives, we can promote energy-efficient practices among building users. Addressing the challenges and fostering a culture of sustainability will significantly enhance the performance of nZEBs, contributing to the EU’s goal of climate neutrality by 2050.
Future cost reductions and measures
Some Member States have set targets or have adopted financial or fiscal measures to favour the use of heat pumps, some also give incentives for the wider use of biomass boilers, which can potentially reduce the cost of this equipment by 2050. In addition, the cost of heat recovery systems is expected to decrease significantly (35-60%). PVs and solar thermal are most commonly implemented renewable technologies and their cost projections indicate that PV cost will decrease between 41% and 56% towards 2050, solar thermal between 22% and 51%. Energy storage will be more and more important in nZEBs. The cost of stationary batteries will drop around 65% in next decades.
Most of the Member States have reported a number of measures to promote the increase of the number of nZEB. These measures are mainly regulatory, financial, informative and educational. Several Member States have also defined long-term milestones related to nZEB implementation.
From nZEBs to ZEBs
It is also clear that nZEBs will have a stronger role in alleviating environmental, social or ethical issues. The future generations of nZEB could be scaled-up and integrated to a district level, shifting the focus from the single building to the district scale, creating Net Zero-Energy District (NZED). This concept includes a wider vision of urban sustainability that foresees innovative solutions for street lighting, urban mobility, waste, and public safety. The advantages of a widespread nZEBs implementation are massive. While decreasing greenhouse gas emissions, nZEBs will increase jobs, energy security, and economic growth in Member States.
The EPBD recast from April 2024 introduces the new definition of Zero-Emission Buildings (ZEBs)that will become the new standard for buildings of new construction or undergoing deep renovation and lead towards the 2050 vision of a decarbonised building stock. The ZEB concept will also address circularity and resource efficiency aspects, e.g., through the calculation of the life-cycle global warming potential. This will become a mandatory indicator to be calculated and disclosed in the Energy Performance Certificates for all new buildings, as of 2030.
The implementation of nZEBs across the EU is a significant step towards achieving climate neutrality by 2050. While there are common elements in the definitions and approaches, variations among member states highlight the need for tailored strategies. With advancements in technology, financial incentives, and a focus on occupant behavior, the transition to more energy-efficient buildings is well underway.
References
https://publications.jrc.ec.europa.eu/repository/handle/JRC122347
https://www.poslovni.hr/hrvatska/nova-nzeb-gradnja-jedna-je-od-okosnica-energetske-tranzicije-u-eu-4391810
https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX%3A52023DC0650#document3
https://ec.europa.eu/commission/presscorner/detail/en/IP_24_1965
Guest blog post by Sandra Magajne and Ljiljana Buček (HEP ESCO Croatia)
