- Practice · 6 marks
Energy audit types and audit procedure
Short answer
An energy audit is a systematic examination of energy use to identify savings opportunities. Preliminary audits are brief (1–3 days), low-cost, with ±20% accuracy; detailed audits involve measurement, energy balances, and costed conservation measures. Steps: planning, walk-through, measurement, analysis, identification of measures, economic evaluation, and reporting with action plan.
What is an energy audit? Differentiate between preliminary (walk-through) and detailed energy audits and describe the steps of a detailed energy audit.
An energy audit is a systematic survey and analysis of energy flows in a building, process or plant to find where energy is used, how efficiently, and how much can be saved at what cost. As per the Bureau of Energy Efficiency (BEE) definition, it verifies, monitors and analyses the use of energy and submits a technical report with recommendations.
Preliminary versus detailed audit
| Point | Preliminary (walk-through) | Detailed (comprehensive) |
|---|---|---|
| Time | 1–3 days | Weeks to months |
| Data | Bills, nameplates, observation | Measurements with instruments |
| Output | Quick list of no-cost and low-cost savings | Full energy balance and costed projects |
| Cost | Low | High |
| Accuracy | About ±20 % | About ±5–10 % |
Steps of a detailed audit
- Plan and pre-audit: define scope, form audit team, collect plant details, process flow, past energy bills (12–36 months), and tariff.
- Walk-through survey: inspect the main users, note obvious wastes and decide where to measure.
- Measurement and data collection: measure electricity, fuel, steam, air, water, temperature and flow of major equipment.
- Analysis: prepare energy balance, specific energy consumption (kWh per unit of product), load profiles, efficiency of equipment, and compare with benchmarks.
- Identify energy conservation measures (ECMs): no-cost (housekeeping), low-cost (maintenance, controls) and high-cost (new equipment).
- Economic evaluation: simple payback = investment ÷ annual saving, net present value and internal rate of return.
- Report and presentation with action plan, then implementation and follow-up (monitoring of savings).
✓ Answer checked by Claude Opus 5.5 (high effort)
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