Developing an Energy Audit Strategy & Plan
Frame the audit before you touch a meter
A defensible audit begins with scope, boundary, and objective - not with a walkthrough. ASHRAE defines three levels: Level I (preliminary screening, low/no-cost measures, rough savings), Level II (energy survey and engineering analysis with end-use breakdown, measured data, and costed measures), and Level III (detailed, investment-grade analysis using calibrated simulation or rigorous modeling). ISO 50002 mirrors this logic: define scope and boundary, collect data, analyze, report.
A complete plan states the objective and intended use of results, the facility boundary and meter map, the baseline period and how it will be weather-normalized, team roles, instrumentation and calibration needs, a data request list, sampling approach, safety and access constraints, deliverable format, and a follow-on measurement and verification (M&V) plan so savings persist.
Traps. Questions that blur Level I with investment-grade analysis; boundaries that silently exclude a separately metered annex or tenant space; baselines drawn from an atypical year (shutdown, expansion, pandemic); and plans that end at the report with no M&V or persistence check.
Rule of thumb
Site energy use intensity (EUI) is the fastest scoping tool: total site energy in kBtu divided by conditioned floor area. Convert electricity at 3.412 kBtu/kWh and natural gas at 0.1 kBtu per therm-equivalent unit (1 therm = 100 kBtu).
Worked example. A 250,000 ft² office uses 5,000,000 kWh and 150,000 therms per year. Electricity: 5,000,000 × 3.412 = 17,060 MBtu. Gas: 150,000 × 0.1 = 15,000 MBtu. Total 32,060 MBtu ÷ 250,000 ft² = 128 kBtu/ft²·yr. Against a typical office stock value near 80 kBtu/ft²·yr, the building is about 1.6× median - enough to justify a Level II with sub-metering of HVAC and plug loads.