When I submit my LOA I usually request 24 months of billing history. Most utilities send me monthly bill PDFs or sometimes a summary spreadsheet. But I'm starting to realize that for demand charge audits I really need the 15-minute interval data to see what's actually driving the peak. Do you include interval data in your standard LOA request or is that a separate ask?
Requesting demand interval data vs just monthly billing summaries
Always request interval data separately. Most utilities will send you billing summaries by default even if you ask for interval data — they have to pull it from a different system. Put it explicitly in your LOA: "24 months of monthly billing statements AND 15-minute interval demand data for the same period." Duke Energy in Pennsylvania has a portal where you can download interval data directly once you have authorization. Others like FirstEnergy make you go through their engineering department which adds another week or two.
Interval data changed my practice. Before I started requesting it I was limited to looking at monthly peak demand on the bill and comparing it to the billing demand. With interval data I can see exactly when peaks occur, identify ratchet clause triggers, spot equipment startup patterns, and find load profile anomalies. For one client in Chicago with ComEd I found their peak demand happened every day at 2:47 PM for exactly 12 minutes. Turned out to be a chiller compressor cycling on. They adjusted the startup sequence and dropped their peak demand by 15%.
Yuri's example illustrates why interval data is essential for any serious demand charge audit. Monthly billing summaries tell you what the peak demand was. Interval data tells you why. And once you know why, you can often help the client reduce it going forward — which is a separate value proposition beyond just finding billing errors. I recommend making interval data a standard part of every commercial LOA request even if you don't always need it. Better to have it and not need it than to find an anomaly on the bill and have to go back for more data.
Added interval data to my standard LOA language. Duke Energy Florida sent it as a CSV file with 15-minute readings — over 70,000 rows for a 24-month period. Took me a while to build a workbook that could analyze it properly but now I have a template I reuse. Already found a demand ratchet issue at a Cincinnati manufacturing client that the monthly bills alone wouldn't have revealed.