Need of energy audit and technique

Energy audit is the systematic study of how energy is used in an industry, to find where it is wasted and to recommend cost-effective measures for saving it. (India's Energy Conservation Act, 2001, a definition also widely used in Nepal's energy efficiency programmes, defines it as "verification, monitoring and analysis of energy use, with a technical report containing recommendations and an action plan to reduce consumption".)

Need of energy audit for an industry

1. Reduce energy cost – energy is a major part (10–40%) of production cost; savings of 10–30% are common.
2. Identify waste – leaks, idle running, oversized motors, poor power factor, poor insulation.
3. Improve productivity and competitiveness – lower unit cost of product.
4. Benchmarking – compare specific energy consumption (kWh/ton) with best practice.
5. Planning – basis for investments in efficient equipment, with payback calculation.
6. Reduce demand charges and penalties – peak load management, pf improvement.
7. Environment – lower fuel use and CO₂ emissions.
8. Equipment reliability – detect overloaded, overheating or unbalanced equipment.
9. Legal and policy compliance – government programmes and standards.

Energy audit technique (methodology)

1. Pre-audit (planning) phase

• Form the audit team, meet management, set objectives.
• Collect data: energy bills (12–36 months), production records, single-line diagram, equipment list.
• Do a walk-through survey to see the major energy users.

2. Audit (execution) phase

• Take detailed measurements with instruments: power analysers, clamp meters, lux meters, flue gas analysers, thermal cameras, flow and pressure meters.
• Prepare an energy balance: where each kWh/litre goes (motors, lighting, compressors, HVAC, furnaces).
• Calculate specific energy consumption; study the load profile, pf and losses.
• Identify energy conservation opportunities (ECOs).
• Techno-economic analysis: savings, investment, simple payback = investment / annual savings, NPV/IRR.

3. Post-audit phase

• Prepare a report with recommendations ranked as no-cost, low-cost and high-cost.
• Implement measures; monitor and verify savings (M&V); repeat the audit periodically.

Pre-audit ─► Data & walk-through ─► Measurements
   ─► Energy balance ─► Find ECOs ─► Cost-benefit
   ─► Report ─► Implement ─► Monitor & verify

Types: preliminary (walk-through) audit – quick, uses existing data; detailed audit – complete measurement and analysis of all systems.