Energy Performance Certificate
A legal document that rates a building's energy efficiency on a scale from A (most efficient) to G (least efficient), based on its annual primary energy consumption. Required in the EU when selling, renting, or commissioning a new building.
What is an Energy Performance Certificate?
An Energy Performance Certificate (EPC) is a formal document that rates the energy efficiency of a building or property on a standardized scale. It summarizes how efficiently a building uses energy for heating, cooling, hot water preparation, ventilation, and lighting. The certificate is based on a comprehensive assessment of the building's envelope, mechanical systems, and energy-related infrastructure.
The EPC is regulated across the European Union by the Energy Performance of Buildings Directive (EPBD), which requires member states to implement this assessment method for all buildings at the point of construction, sale, or rental. In Slovakia, the legal framework is established by Law 555/2005 Z.z. on energy efficiency of buildings and is enforced by certified energy assessors.
| Energy Class | Description | Annual Primary Energy (kWh/m²·year) | Typical Building Type |
|---|---|---|---|
| A0+ / A1 | Nearly zero-energy building; exceptional efficiency | <50 (A0+); 50–75 (A1) | NZEB, new passive houses |
| B | Good efficiency; meets current standards | 75–150 | Modern renovated buildings |
| C | Average efficiency | 150–250 | Well-maintained existing homes |
| D–E | Above-average energy consumption | 250–400 | Older residential buildings |
| F–G | Poor efficiency; high energy demand | >400 | Unrenovated, pre-1980s properties |
How does an Energy Performance Assessment work?
An EPC assessment is conducted by a trained and certified energy auditor or engineer who examines the building's physical characteristics and energy systems. The auditor gathers data on building geometry, construction materials, insulation levels, thermal bridges, windows, doors, heating and cooling systems, hot water production, ventilation systems, and renewable energy installations if present.
The assessment uses standardized calculation methods to determine the annual primary energy requirement of the building. In Slovakia, this follows the methodology established by the STN 73 0540 Thermal Protection Standard and national implementing regulations. The assessor then assigns the building to the appropriate energy class (A0+ through G) and generates a detailed report with recommendations for cost-effective energy improvements.
What do the energy classes mean?
The energy classes provide a simple, visual way for building owners and potential buyers or tenants to understand a property's energy performance relative to others. Class A0+ represents nearly zero-energy consumption and is the most desirable rating for new construction and renovations. Class A1 is also very efficient. Class B meets modern building standards and is a realistic goal for well-executed renovations of existing stock.
As you move down the scale toward class G, energy consumption and operational costs increase significantly. A building rated G may consume two to three times more energy than an equivalent class B property. The classification is based on primary energy consumption, which accounts for the energy losses in electricity generation and distribution, making the rating more comprehensive than simple delivered-energy measures.
| Rating Class | Energy Efficiency Level | Common Scenarios |
|---|---|---|
| A0+, A1 | Exceptional (Nearly zero-energy) | New passive houses, NZEB-compliant buildings, recently deep-retrofitted homes |
| B | Good (Modern standard) | New buildings meeting EU regulations, substantially renovated properties |
| C, D | Average | Well-maintained pre-2010 buildings, partially upgraded properties |
| E, F, G | Poor (High consumption) | Older unrenovated buildings, pre-1970s properties with minimal upgrades |
When is an EPC legally required in Slovakia?
In Slovakia, an Energy Performance Certificate is legally mandatory in the following situations: (1) when a building or part of a building is sold; (2) when a building is rented to a new tenant; (3) when a new building is completed and first commissioned; (4) when a building undergoes a major renovation affecting more than 25% of the surface area of the building envelope.
The owner of the building is responsible for obtaining a valid certificate before completing these transactions. When selling, the certificate must be handed over to the new owner. When renting, the landlord must provide a certified copy to the tenant. Exemptions include protected cultural monuments, churches and places of worship, temporary structures used for less than two years, and buildings with a useful floor area below 50 m².
How long is an Energy Performance Certificate valid and what are transfer obligations?
An Energy Performance Certificate issued in the EU is valid for a maximum period of 10 years from the date of issue. After this period expires, if the building is to be sold or rented, a new assessment must be conducted and a fresh certificate obtained. During its validity period, the same certificate may be used for multiple transactions.
When transferring ownership or entering into a new rental agreement, the current owner or landlord must provide a valid, unexpired EPC to the new owner or tenant. The certificate includes information on the building's energy consumption, the energy class rating, identification of the qualified assessor, and practical recommendations for cost-effective energy improvements. Keeping an up-to-date certificate is not only a legal obligation but also essential for property valuation and marketability, as potential buyers increasingly consider energy costs and environmental impact.
How is an Energy Performance Certificate different from an Energy Audit?
While both an EPC and an energy audit involve assessing building energy performance, they serve different purposes and have different regulatory requirements. An EPC is a standardized, legally mandated assessment required for property transactions and new construction. It uses simplified, streamlined calculation methods to assign a single energy class rating and provide general renovation recommendations.
An energy audit, by contrast, is a more detailed, comprehensive investigation typically performed for buildings where the owner wants to understand opportunities for energy savings before investing in major upgrades. Audits include detailed inspections, sometimes with thermal imaging or blower-door testing, and produce specific, prioritized recommendations with estimated costs and savings. An audit is not legally required for property transactions but is highly valuable for planning a cost-effective renovation strategy. Many building owners commission an energy audit after obtaining their EPC to guide targeted improvements.
What practical applications does the Energy Performance Certificate have?
The EPC serves multiple practical functions. For buyers and tenants, it provides transparent information about the long-term energy costs of a property, helping inform purchasing or leasing decisions. For owners and real estate professionals, the certificate affects property valuation and marketability—a building with a poor energy rating may sell for significantly less or attract fewer tenants, while an efficient, well-rated building commands premium value.
For builders and renovation contractors, the EPC serves as a compliance document proving that new construction and major renovations meet EU energy-efficiency standards. Governments use aggregated EPC data to monitor building stock energy performance, identify neighborhoods needing renovation support, and design targeted energy-efficiency programs. Recent research indicates that EPC data, combined with thermal imaging and machine learning, can accelerate the identification of buildings with high retrofit potential and support large-scale renovation campaigns at lower cost, making it easier for decision-makers to prioritize public funds.
Frequently asked questions
- What does EPC stand for?
- EPC stands for Energy Performance Certificate. It is a standardized document that assesses and rates the energy efficiency of a building based on factors like insulation, heating systems, ventilation, and other energy-consuming components.
- What do the energy ratings A through G mean?
- The ratings indicate efficiency level: A (A0+/A1) is very efficient and low-energy, B is good and meets current standards, C-D are moderate, E-F show high energy demand, and G indicates very high energy consumption and poor efficiency.
- How long is an Energy Performance Certificate valid?
- In the EU, an EPC is valid for 10 years from the date of issue. After expiration, a new assessment must be conducted if the building is sold, rented, or undergoes a major renovation.
- When is an EPC legally required?
- An EPC is mandatory when a building is sold, rented to a new tenant, newly constructed, or undergoes a significant renovation. In Slovakia, exemptions include heritage properties, churches, temporary structures, and buildings under 50 m².
- Can I improve my building's EPC rating?
- Yes. The certificate includes cost-effective recommendations for improvements such as enhanced insulation, installing modern heating systems, upgrading windows, and improving ventilation. Implementing these recommendations can raise your energy class.
- Does an EPC cost money?
- Yes. Certified energy assessors charge a fee for conducting the assessment and issuing the certificate. Costs vary by region and building complexity, but are typically a fixed or area-based fee.