Decree on Energy Performance of Buildings

What is the Slovak Decree on Energy Performance of Buildings?

The Decree on Energy Performance of Buildings (Vyhláška o energetickej hospodárnosti budov) is Slovakia's national legal instrument that sets binding energy efficiency requirements for all buildings on Slovak territory. Effective 1 April 2025, it replaced the previous building act dating from 1976 and represents Slovakia's formal implementation of the EU Energy Performance of Buildings Directive (EPBD, revised 2024). The decree is not new policy—it is the codification of Slovakia's legal obligations as an EU member state, combined with national procedures for enforcement, certification, and funding.

The decree operates at two levels: it sets the legal framework for mandatory energy performance certification (requiring architects and developers to calculate and declare building energy metrics) and establishes renovation targets and timelines for the existing building stock. For new construction, the decree mandates that all residential buildings achieve nearly zero-energy status with Energy Class A0. For existing buildings, it defines minimum energy performance standards that trigger renovation obligations for the lowest-performing 16% of non-residential buildings by 2030 and 26% by 2033.

How did the decree replace the previous building legislation?

Slovakia's previous building act (Law 50/1976 Coll.) governed building permitting, construction, and inspection for over 45 years. While energy efficiency was mentioned, there was no unified system for energy performance calculation or certification. The new Building Act (Zákon o výstavbe č. 25/2025 Z. z.), which entered force on 1 April 2025, integrated energy performance as a core regulatory pillar. The decree sits within this broader act and incorporates Slovakia's national climate zone data, thermal protection standards (STN 73 0540), and adapted EU calculation methodologies.

The transition was significant: existing buildings that received energy certificates under the old system (2008 onwards) retain those certificates until their 10-year validity expires, but all new assessments use the new decree's A0–G classification scale. Architects and engineers designing buildings after 1 April 2025 must comply with the new decree or face refusal of building permits.

What energy performance requirements does the decree establish?

The decree establishes two categories of requirements: mandatory for new buildings, and progressive for existing buildings. For all new residential buildings, the decree mandates nearly zero-energy performance, meaning annual primary energy consumption must not exceed approximately 54 kWh/m²/year (energy class A0), with no fossil fuel combustion on site. This is achieved through high insulation (typically U-values well below 0.15 W/m²K), heat recovery ventilation, heat pumps or biomass heating, solar thermal or photovoltaic systems, and airtightness testing (blower door tests, with n50 <0.6 air changes per hour).

For new non-residential buildings, the decree requires nearly zero-energy status by 2030. For existing buildings, the decree introduces minimum energy performance standards (MEPS): member states (including Slovakia) must identify their worst-performing 16% of non-residential buildings and require renovation by 2030, progressing to 26% by 2033. Residential buildings must achieve a 16% reduction in average primary energy use by 2030. Buildings undergoing major renovation (affecting more than 25% of building envelope surface area) must improve to meet enhanced energy standards regardless of whether they fall within the percentage targets.

The decree specifies that energy performance is calculated using harmonized ISO standards adapted for Slovakia: EN ISO 52000-1 (general methodology), EN ISO 52016-1 (heating and cooling demand), and related standards. Each proposed or existing building receives a primary energy indicator (in kWh/m²/year) which determines its energy class from A0 to G.

What types of buildings must be certified under the decree?

Mandatory certification applies to all buildings with useful floor area exceeding 50 m². This includes single-family homes, apartment blocks, office buildings, retail and commercial spaces, schools, hospitals, libraries, hotels, restaurants, factories, and warehouses. Public buildings (owned or operated by government bodies) receive enhanced scrutiny—they must demonstrate energy class compliance and publish their performance data, making them benchmarks for the broader building stock.

Exemptions are narrow: temporary buildings expected to stand less than 18 months, agricultural buildings under 50 m² with no climate control, industrial facilities and processes where the building is incidental to manufacturing, and buildings of outstanding cultural or architectural heritage where energy improvements would compromise their protected status. This heritage exemption is recognized in EU law, and Slovakia applies it to listed historical buildings and monuments.

How does the decree define energy class and who assigns it?

The decree defines energy class using the harmonized EU scale A0–G introduced by the 2024 EPBD revision. Energy Class A0 represents nearly zero-energy buildings exceeding zero-energy threshold by at least 20%; Class A represents zero-emissions buildings; Classes B–G represent progressively higher energy demand. The thresholds for each class are set nationally by Slovakia based on its climate zones and building typology, but the structure is identical across all EU member states as of 29 May 2026.

Energy class is determined and assigned by qualified energy auditors (certifikovaný energetik) or qualified architects who prepare the Energy Performance Certificate (EPC). For new buildings, the class is calculated during design based on planned systems and materials. For existing buildings undergoing sale, rental, or major renovation, an auditor assesses the actual building and issues a certificate. The decree specifies that calculations must follow national methodology aligned with EU standards; auditors must be independently verified and hold ongoing professional credentials.

What is the role of the Energy Performance Certificate under the decree?

The Energy Performance Certificate is the formal document proving a building's energy class and compliance status. Under the decree, an EPC is legally required in five scenarios: (1) when a building is sold; (2) when a building is rented to a new tenant; (3) upon completion of new construction; (4) when a building undergoes major renovation affecting >25% of envelope surface; (5) upon request by any person inspecting the building's energy status.

The EPC contains the building's energy class (A0–G), its annual primary energy indicator (kWh/m²/year), recommendations for cost-effective improvements, estimated improvement costs and payback periods, and required renovations under the decree's MEPS framework. For classes A–C, the certificate is valid 10 years; for D–G, it is valid 5 years. After expiration, a new certificate must be obtained if the building changes hands or undergoes major renovation. This ensures the market always has current information about building performance.

How does the Slovak decree relate to the EU Energy Performance of Buildings Directive?

The Slovak decree is the national transposition of the Energy Performance of Buildings Directive (EPBD, revised by EU/2024/1275 in May 2024). The EPBD is EU-wide law binding all member states; each state must convert it into national legislation by specified deadlines. Slovakia's deadline for full transposition of the 2024 EPBD revision is 29 May 2026; the 1 April 2025 effective date of Building Act 25/2025 and this decree represents Slovakia's early implementation, adopting the harmonized A0–G energy classification scale and new MEPS requirements ahead of the EU minimum deadline.

The relationship is hierarchical: the EPBD sets the binding requirements (e.g., minimum energy performance standards for buildings, renovation targets, zero-emission requirements for new construction); the decree translates these into Slovak procedures, enforcement authority, cost-sharing mechanisms, and links to other Slovak standards like STN 73 0540 thermal protection. A building that complies with the Slovak decree is also compliant with the EPBD. The decree does not exceed EPBD obligations (it would be illegal under EU law to set looser standards), but it may specify procedural details the EPBD leaves to member states.

What are the key differences between the decree and other Slovak building standards?

Slovakia's thermal protection standard STN 73 0540 has been the primary guide for minimum insulation values (U-values) since 1994. STN 73 0540 specifies that external walls must have U-values not exceeding 0.20 W/m²K for new buildings; windows, 0.17 W/m²K, etc. The decree is not a replacement but a consumer of STN 73 0540: it uses the standard's thermal properties in energy calculations, but adds the holistic layer of annual primary energy accounting. A building can meet STN 73 0540 insulation minimums and still fail to achieve the decree's energy class requirements if its heating, ventilation, or renewable energy systems are inefficient.

The decree also supersedes older design guidance. For example, natural ventilation without heat recovery was once acceptable under STN 73 0540 minimum compliance. The decree now effectively requires heat recovery ventilation (HRV) or heat pump ventilation for nearly zero-energy buildings, because the annual primary energy budget cannot be met without capturing waste heat from exhaust air.

How do Slovak architects and engineers apply the decree in practice?

During the design phase, architects and mechanical engineers use energy simulation software (calibrated to the Slovak national methodology based on EN ISO 52016-1) to model the proposed building's annual energy consumption. They input: building geometry, envelope U-values, window solar gain, internal heat sources, occupancy patterns, heating system type and efficiency, ventilation rates and heat recovery, domestic hot water systems, and any renewable energy sources. The simulation produces a primary energy indicator (kWh/m²/year) which is cross-referenced against the decree's energy class thresholds to assign a design energy class.

If the design does not achieve the required class (A0 for new residential), the team iterates: improving insulation, upgrading to a more efficient boiler or heat pump, adding solar PV or solar thermal, reducing ventilation losses through higher-performance heat recovery, or tightening air leakage targets. Once the design meets the class target, the building permit can be issued. Before handover, a blower door test is conducted to verify airtightness (n50 <0.6 required for NZEB), and the certificate is issued based on design calculations (for new buildings) or measured performance (if certified as Passive House).

For existing buildings, auditors conduct site visits, measure or estimate thermal properties, record heating system age and efficiency, and inspect ventilation and renewable energy systems. They then run the same calculation software to produce an energy class for the current building. If the building falls into Slovakia's worst 16–26% (for non-residential), the decree obligates renovation: the auditor recommends cost-effective improvements and a timeline.

What is the timeline for Slovakia's compliance with the decree and related EPBD targets?

The decree came into force 1 April 2025, ahead of the EU EPBD transposition deadline of 29 May 2026. Key milestones include: new residential buildings must be NZEB/Class A0 (effective immediately, 1 April 2025); new non-residential buildings must be NZEB by 1 January 2028 (per EPBD); the worst 16% of non-residential buildings must be renovated to Class F or better by 1 January 2027 (earlier than the 2030 EU target, pending Slovak implementation details); residential buildings must achieve 16% average primary energy reduction by 31 December 2030; the worst 26% of non-residential buildings must be renovated by 1 January 2033. Slovakia is expected to publish its national building renovation plan by 31 December 2026, outlining financing mechanisms and subsidy programs (such as Obnov Dom) to support compliance.

What are common misconceptions about the Slovak energy performance decree?

Myth: The decree only applies to new buildings. Fact: The decree applies equally to new and existing buildings. New buildings have stricter requirements (A0 mandatory), but existing buildings face renovation obligations if they are poor performers or undergo major work. The decree's scope is comprehensive across the entire Slovak building stock.

Myth: Energy class is just a marketing label. Fact: Under the decree, energy class is a legal designation. It determines which buildings must be renovated, affects property value and insurability, and is required in all property transactions. Non-compliance can result in administrative penalties and refusal of building permits.

Myth: Passive House certification is the same as meeting the decree's requirements. Fact: Passive House is a separate, voluntary performance standard. A Passive House almost always exceeds the decree's A0 requirement, but a building complying with the decree is not automatically Passive House certified. The decree is the legal minimum; Passive House is an optional premium designation.

Myth: Older buildings with valid energy certificates do not need to be re-assessed. Fact: Certificates issued before 1 April 2025 remain valid until expiration, but upon sale, major renovation, or rental, a new certificate using the decree's current A0–G scale must be obtained. This ensures current market information and compliance with the new standard.

Myth: The decree applies only to large commercial buildings. Fact: The decree applies to all buildings exceeding 50 m² usable floor area, including family homes. The only building category exempt is those under 50 m² or with no climate control. Single-family residential design is directly subject to the decree's A0 requirement for all new construction.

How does the decree impact residential design in Slovakia?

For architects designing homes in Slovakia, the decree represents a hard regulatory floor: every new residential building must achieve Energy Class A0 and nearly zero-energy performance. This is not aspirational guidance; it is a legal requirement for building permits to be issued. The practical implication is that envelope design, mechanical systems, and renewable energy integration are non-negotiable components of all residential projects.

This shifts the design conversation. Rather than debating whether to invest in extra insulation or heat recovery ventilation, these decisions are predetermined by law. The architect's role becomes optimizing cost-effectiveness and occupant comfort within the A0 envelope. This has favored passive design strategies (high insulation, strategic window placement, thermal mass) combined with heat pumps and solar thermal or PV systems as the standard model across Slovak residential construction since April 2025.

For existing residential properties, the decree provides a roadmap for renovation through the energy class system and the audit recommendations. A Class C or D home in Slovakia can improve energy class progressively through targeted upgrades (new windows, insulation, boiler replacement with heat pump, solar panels), each improvement documented in updated energy audits. While no legal mandate exists to renovate existing homes, energy class increasingly affects property value and tenant demand, making Class B or A a practical investment target in the residential resale and rental markets.