Maria from Austin. Been doing residential audits and just moved into commercial. Interval data is new territory for me. I received a 12-month interval data file from a utility. It is a spreadsheet with timestamps every 15 minutes and kWh readings. How do I turn this into something useful for demand analysis?
How to read interval data — practical walkthrough for new auditors
Derek from Charlotte. The interval data gives you energy in kWh per 15-minute interval. To get demand in kW multiply each interval kWh by 4 — because four 15-minute intervals make an hour. So 25 kWh in a 15-minute interval equals 100 kW demand.
Oh that is simpler than I expected. So the billing demand is just the highest kWh interval times 4?
Derek again. Exactly. Find the row with the highest kWh value, multiply by 4, and you have the peak demand for that period. If you sort by kWh descending the top row is your billing demand. Compare that to the bill.
Lisa from Portland. Once you have done the basic peak demand verification look for patterns. Does the peak always happen on the same day of week or time of day? That tells you what equipment is responsible. Patterns are your roadmap to both error detection and cost reduction recommendations.
Lisa, what if the interval data and the bill match but the peak seems way higher than what the client thought their equipment could draw?
Lisa again. That is a load investigation, not a billing dispute. Start with the demand spike timestamp and ask the client what was running at that exact moment. Sometimes they find equipment they forgot was on the circuit, or they find a fault condition that created an abnormal draw.
Phil from Denver. Also check whether the interval data file has any missing readings — gaps where no data was recorded. The utility should flag estimated data with an E marker. If the billing demand comes from an estimated interval rather than an actual reading you have grounds for a dispute.