What Is an Energy Audit?
An energy audit is a systematic review of how energy is consumed within a building or operation. It identifies where energy is being used, where it is being wasted, and what measures would deliver the greatest savings. Whether you manage a small office or a large industrial facility, a well-executed audit is the foundation of any credible energy management programme.
Types of Energy Audits
Energy audits are typically categorised into three levels of depth:
- Level 1 – Walk-Through Assessment: A brief, low-cost inspection that identifies obvious inefficiencies and quick wins. Suitable for smaller premises or as a preliminary screen.
- Level 2 – Detailed Audit: A thorough investigation involving metering, data analysis, and detailed cost-benefit analysis for recommended measures. Suitable for most commercial and industrial premises.
- Level 3 – Investment-Grade Audit: A rigorous, engineering-level study used to underwrite significant capital investments. Involves detailed modelling and uncertainty analysis.
Most businesses will benefit most from a Level 2 audit conducted by a qualified energy assessor.
Step-by-Step: How to Conduct an Energy Audit
Step 1: Gather Utility Data
Collect at least 12–24 months of electricity, gas, and fuel bills. Look for:
- Total consumption and cost by period
- Demand charges (peak kW) on electricity bills
- Seasonal patterns and unexplained spikes
Many utilities now offer online portals where you can download interval meter data (15-minute or hourly readings), which provides far more granular insight.
Step 2: Inventory Energy-Consuming Equipment
Walk through every area of your premises and document all significant energy-consuming assets:
- HVAC systems (chillers, boilers, air handling units, packaged units)
- Lighting (type, wattage, control systems)
- IT and data equipment (servers, workstations, networking hardware)
- Industrial machinery, compressors, and process equipment
- Refrigeration and catering equipment
- Hot water systems
Record rated power (watts or kW), estimated operating hours, and age/condition for each item.
Step 3: Measure and Monitor
Clamp meters and plug-in energy monitors can be used to take spot readings or short-term sub-metering measurements on key equipment. This validates nameplate data and reveals actual consumption patterns. For a thorough audit, consider installing temporary sub-meters on circuits serving major loads for several weeks.
Step 4: Identify Waste and Inefficiencies
Common findings in commercial energy audits include:
- Equipment running outside occupied hours (overnight, weekends)
- Poor HVAC controls allowing heating and cooling to run simultaneously
- Compressed air system leaks (can account for 20–30% of compressor energy)
- Outdated, inefficient lighting
- Poorly insulated pipes or building fabric
- High standby loads from IT or catering equipment
Step 5: Develop Recommendations and Prioritise
For each identified inefficiency, estimate the energy saving, implementation cost, and simple payback period. Group recommendations into three tiers:
- No-cost / low-cost: Behaviour changes, schedule adjustments, maintenance tasks — implement immediately
- Medium investment: Control upgrades, LED retrofits, insulation — plan within 1–2 years
- Capital investment: Equipment replacement, building fabric works — evaluate with full financial analysis
Step 6: Implement, Measure, and Report
An audit is only valuable if it leads to action. Assign responsibility for each recommendation, set a timeline, and establish a baseline so you can measure actual savings achieved. Regular reporting keeps energy management on the management agenda and demonstrates progress toward sustainability targets.
Do You Need a Professional Auditor?
For simple premises, a competent facilities manager can conduct a credible Level 1 audit. However, Level 2 and Level 3 audits are best carried out by a certified energy auditor (look for credentials such as Certified Energy Auditor (CEA) from the Association of Energy Engineers, or national equivalents). Professional auditors bring calibrated equipment, benchmarking databases, and engineering expertise that deliver more reliable findings and savings estimates.
Final Thought
An energy audit is not a one-time event — it is a starting point. The most energy-efficient businesses revisit their audits every few years and continuously monitor their consumption between audits. Treat energy management as an ongoing discipline, not a project, and the savings will compound over time.