Energy Audits and Instrumentation
The three audit levels
ASHRAE Standard 211 defines the levels the exam expects. Level 1 is a walk-through: utility bill analysis, rough benchmarking, a list of low-cost opportunities, and no rigorous savings calculations. Level 2 is an energy survey and analysis: end-use breakdown, measured or trended data, financial analysis of individual measures, and a recommended package. Level 3 is a detailed analysis of capital-intensive modifications, adding calibrated models, hourly simulation, and tighter cost estimates. The common trap is assigning a chiller plant replacement or boiler overhaul to Level 2; capital-intensive work requires Level 3 rigor.
Instrumentation and data quality
Match the tool to the measurement: power analyzers and watt-hour loggers for electrical loads; clamp-on or ultrasonic flow meters where pipe cannot be broken; pitot tube traverses for ducts; flow hoods for grilles; hot-wire anemometers for open faces; infrared imaging for envelope and electrical hot spots; combustion analyzers for boilers (oxygen, CO, stack temperature). Record accuracy, calibration date, and measurement boundary, because both Standard 211 and IPMVP depend on defensible boundaries. Logging interval must match the load cycle; spot readings miss duty cycling.
Metrics and rule of thumb
EUI (kBtu/ft2-yr) = total site energy in kBtu / conditioned floor area, with 1 kWh = 3,412 Btu. Degree-days support weather normalization. A typical U.S. office falls on the order of 50 to 70 kBtu/ft2-yr site energy, so benchmark against a regional median rather than a national average. Never base savings on nameplate data when a measured load profile exists.