Q6Electrical Energy Conversion And Auditing
Question
Q.6. Difference between audit methods.
Answer
Audit methods differ mainly in the direction of analysis: the direct (top-down) method starts from total plant input and allocates it downward, while the bottom-up (component-wise) method builds up total consumption from individually measured equipment loads, offering greater granularity.
Energy audit methods differ chiefly in their analytical approach: the top-down (direct) method starts from the facility's total metered energy input (from utility bills) and allocates it downward among major sub-systems based on nameplate ratings and estimated operating hours, providing a quicker but less precise result; the bottom-up (component-wise/measurement-based) method instead measures energy consumption directly at each individual piece of equipment or process step using portable instruments, then sums these measurements upward to reconstruct total facility consumption, offering much greater accuracy and granularity for identifying specific savings opportunities, though requiring significantly more time, instrumentation, and effort to complete.