Energy Performance Certificates and Building Certification
What an EPC is
An energy performance certificate states the building's calculated or measured energy performance, expressed as a primary energy indicator and a class (A–G in Bulgarian practice), with recommendations for improvement. It is issued by a certified auditor/assessor and registered. Certificates are required for buildings sold, rented, or newly constructed, and for public buildings above the floor-area threshold, where the certificate is displayed publicly.
Methodology concepts
Know the difference between asset rating (calculated from the building's characteristics under standard assumptions) and operational rating (based on actual metered consumption). Bulgarian certificates are methodology-based; actual consumption is not the certificate value. Primary energy factors convert delivered energy by carrier into primary energy; CO2 emission factors are separate. The reference building and cost-optimal minimum requirements underpin the class thresholds.
Traps in questions
- Assuming the certificate equals the energy audit (it does not; audit is deeper).
- Forgetting the certificate must be shown to the prospective buyer/tenant before contract.
- Confusing primary energy with delivered energy or with CO2.
- Treating the class as a legal pass/fail for existing buildings (it is informational; minimum requirements apply to new builds and major renovations).
- Ignoring validity periods and re-issue triggers after major renovation.
Worked example
A building uses 120 kWh/m²/yr delivered electricity; with a primary energy factor of ~2.5 the primary indicator is ~300 kWh/m²/yr, which may push it several classes lower than the delivered figure suggests. Always check which indicator the class refers to.
Rule of thumb
Quote the indicator and its basis (delivered vs. primary, calculated vs. metered) whenever you state a class.