Which energy audit is the most expensive?

• A. Lighting Audit
• B. Process Improvement Audit
• C. Technical/ Engineering Audit
• D. Preliminary Audit

Answer: (C)

The most expensive audit is the one that goes deepest into how energy is actually used across systems, with rigorous diagnostics and engineering analysis. A technical/engineering audit involves detailed on-site measurements of equipment performance, energy balances, and system integration, often requiring specialized instruments, multiple engineers, and longer field work. It may also involve engineering calculations or simulations to quantify savings and develop capital-justified recommendations, which drives up cost. By comparison, a lighting audit is narrower and quicker, focusing on lighting systems with simpler measurements; a preliminary audit is high-level and low-cost by design; and a process improvement audit, while potentially data-intensive, usually doesn’t demand the same level of engineering testing or system-wide modeling as a full technical audit.