Bulgarian Energy Efficiency Consultant Exam cheat sheet
Bulgarian Energy Efficiency Consultant Exam · Keep the key ideas within reach.
Legal and Regulatory Framework for Energy Efficiency
Energy Efficiency Act (ZEE) transposes EU Energy Efficiency Directive 2012/27/EU; mandatory energy audits for large enterprises every 4 years.
Energy Performance of Buildings Act (ZEEU) implements EPBD 2010/31/EU; requires EPC for new buildings, sale, rent, and public buildings over 250 m².
Energy from Renewable Sources Act (ZEVI) sets renewable targets and guarantees of origin; supports NZEB renewable share requirements.
Spatial Development Act (ZUT) governs building permits; energy efficiency requirements integrated into investment design.
Energy Act (ZE) regulates electricity/gas markets, licensing, and consumer protection; relevant for on-site generation and storage.
EU ETS and Effort Sharing Regulation set carbon constraints; Bulgaria's integrated energy and climate plan (NECP) sets national targets.
Minimum energy performance requirements for new buildings and major renovations are set by ordinance; cost-optimal levels reviewed every 5 years.
Penalties for non-compliance: fines for missing EPC, non-certified auditors, and failure to implement mandatory audit recommendations.
Public procurement rules require life-cycle cost analysis and energy efficiency criteria for public buildings.
Energy Auditing Methodology and Standards
Energy audit per EN 16247-1: define scope, collect data, analyze energy use, identify measures, report; quality assurance required.
Audit levels: walk-through (screening), detailed (energy balance, measurements), investment-grade (financial analysis).
Energy balance: Energy input = useful energy + losses; losses include envelope, ventilation, distribution, and conversion.
Degree-day method: HDD = Σ(T_base − T_mean) for days when T_mean < T_base; used for normalized heating energy.
Measurement plan: ensure instruments calibrated, sampling frequency adequate, and uncertainty documented.
Baseline establishment: use at least 12 months of data; adjust for weather, occupancy, and production changes.
Energy performance indicators (EnPI): kWh/m²·year, kWh/unit production, or kWh/employee; normalize for comparison.
Audit report must include executive summary, methodology, findings, prioritized measures, and cost-benefit analysis.
Building Envelope and Thermal Performance
Thermal transmittance U = 1/R_total (W/m²K); R_total = R_si + ΣR_layers + R_se.
Thermal resistance of layer R = d/λ (m²K/W), where d is thickness (m) and λ is thermal conductivity (W/mK).
Thermal bridging: linear thermal transmittance Ψ (W/mK); include in envelope heat loss calculation.
Minimum U-values for new residential buildings in Bulgaria: external walls ≤ 0.28 W/m²K, roof ≤ 0.20, windows ≤ 1.30 (typical).
Air permeability n50 (air changes per hour at 50 Pa) measured by blower door; target ≤ 3 h⁻¹ for NZEB.
Moisture control: avoid condensation by ensuring surface temperature above dew point; use vapor barrier on warm side.
Solar heat gain coefficient (SHGC) and glazing area affect cooling load; use shading and low-e coatings.
Envelope heat loss Q = U × A × ΔT (W); annual energy = Q × HDD × 24 / 1000 (kWh).
HVAC, Lighting, and Building Energy Systems
Heating/cooling load calculation per EN 12831; consider internal gains, ventilation, and envelope losses.
Boiler efficiency: seasonal efficiency = useful heat output / fuel energy input; condensing boilers achieve >90% (LHV).
Heat pump COP = Q_heat / W_input; SCOP accounts for seasonal variations; ground-source higher efficiency than air-source.
Ventilation heat recovery efficiency η = (T_supply − T_outdoor) / (T_extract − T_outdoor); typical 70–85%.
Lighting power density (LPD) limits: office ≤ 10 W/m², retail ≤ 12 W/m² (typical); use LED and controls.
Lighting controls: occupancy sensors, daylight dimming, and scheduling can reduce lighting energy 20–40%.
Chiller COP and IPLV: part-load performance critical; variable speed drives improve efficiency.
Distribution losses: pipe insulation and duct sealing reduce losses; hydronic balancing essential.
Energy Performance Certificates and Building Certification
EPC is based on calculated energy use for standard occupancy; includes energy class (A–G) and recommendations.
Bulgarian EPC scale: A+ ≤ 15 kWh/m²·year, A ≤ 30, B ≤ 60, C ≤ 100, D ≤ 150, E ≤ 200, F ≤ 250, G > 250 (primary energy).
EPC valid 10 years; required for new buildings, sale, rent, and public buildings >250 m².
EPC must be issued by certified energy auditor; auditor registration with Sustainable Energy Development Agency (SEDA).
Certification schemes: BREEAM, LEED, DGNB; assess energy, water, materials, indoor environment, and innovation.
NZEB definition: very high energy performance, renewable energy share ≥ 55% (Bulgaria for public buildings).
EPC input data: building geometry, envelope U-values, systems efficiency, renewable contribution, climate data.
EPC recommendations must be cost-effective; include payback and priority.
Energy Efficiency Measures and Economic Analysis
Simple payback = investment cost / annual savings (years).
Net Present Value (NPV) = Σ (annual cash flow / (1+r)^t) − initial investment; accept if NPV > 0.
Internal Rate of Return (IRR): discount rate making NPV = 0; accept if IRR > required return.
Levelized cost of energy (LCOE) = total lifecycle cost / total energy produced; compare alternatives.
Life-cycle cost analysis includes investment, operation, maintenance, replacement, and energy costs over lifetime.
Energy savings can be estimated using deemed savings, engineering calculations, or measured data.
Prioritize measures by cost-effectiveness: low-cost operational measures first, then envelope, then systems.
Financing options: grants, ESCO energy performance contracts, green loans, and tax incentives.
Renewable Energy Integration and Nearly Zero-Energy Buildings
Solar PV: annual yield = installed capacity (kWp) × specific yield (kWh/kWp·year); Bulgaria ~1,200–1,400 kWh/kWp.
Solar thermal: collector efficiency η = useful heat / solar radiation; typical 40–60% for flat plate.
Heat pumps: renewable share depends on SPF; SPF ≥ 2.5 qualifies as renewable (RES Directive).
Biomass boilers: efficiency 85–92%; consider fuel sourcing and emissions.
NZEB renewable share: Bulgaria requires ≥ 55% for public buildings, ≥ 35% for other new buildings (typical).
On-site renewable integration: size to match load profile; use storage to increase self-consumption.
Grid connection rules: net metering available for small PV; feed-in tariff replaced by premiums.
Energy storage: battery round-trip efficiency 85–95%; size for peak shaving or self-consumption.
Measurement, Verification, and Energy Monitoring
IPMVP options: A (retrofit isolation, key parameters), B (retrofit isolation, all parameters), C (whole facility), D (calibrated simulation).
Baseline period: minimum 12 months; adjust for weather, occupancy, and production using regression models.
Measurement uncertainty: instrument accuracy, sampling error, and model error; report at 90% confidence.
Energy monitoring: sub-metering of major end-uses (HVAC, lighting, plug loads) at 15-minute intervals.
M&V plan must define baseline, boundaries, measurement methods, and verification procedures.
Weather normalization: use heating/cooling degree days or regression with outdoor temperature.
Savings = baseline energy (adjusted) − reporting period energy ± adjustments.
Data quality: check for gaps, outliers, and meter calibration; document all adjustments.
Professional Ethics, Reporting, and Consultant Practice
Conflict of interest: disclose any financial interest in recommended measures or suppliers.
Confidentiality: protect client data; do not disclose without consent, except as required by law.
Competence: only accept work within your expertise; use qualified specialists for sub-areas.
Reporting: present findings objectively, distinguish facts from assumptions, and cite data sources.
Independence: recommendations must be based on technical and economic merit, not commissions.
Legal compliance: follow SEDA registration, code of ethics, and continuing professional development.
Documentation: retain audit records for at least 5 years; ensure traceability of calculations.
Client communication: explain limitations, uncertainties, and assumptions clearly in the report.