How much of a pump-scheduling saving survives when one hot day sets the month's demand charge?

What it found

infra-pumpdemand billed Net3 pump schedules on PG&E Schedule B-19 with every day identical and found that schedules idling the 310 kW booster cut the bill 56–67 %. A demand charge is set by the highest 15-minute kW of the month, so this project re-simulates all 21,806 schedules with at most two daily on-runs at a 900 s step on days with every Net3 demand scaled by 0.8, 1.0, 1.2, 1.4 and 1.6, and bills 30-day months of ordinary days plus 1, 3 or 10 hot days. With demand 1.5 % above Net3’s shipped level the lowest feasible peak among one-run schedules (tanks above minimum, 20 psi, tanks back to within 0.1 % of the day’s demand) jumps from 63 kW to 310 kW, the booster; at +20 % it is 372 kW, the same as the shipped schedule. A month with three days at +20 % saves 43.5 % (summer) and 18.7–19.2 % (winter, spring) against the shipped schedule on the same month, against 56, 66 and 67 % with identical days; at +40 % 1at +40 % 3–14 %ndash;15 %; at +60 % no schedule meets the periodic tank test. Choosing a different schedule for the hot days than for ordinary days adds at most 4.2 points (summer; under 1 point in winter and spring) over one schedule feasible on every day. The day multiplier is a sweep, not a measured demand distribution; each day is simulated as periodic (tanks return to where they started), so a hot day cannot borrow from its neighbours; the threshold is for one-run schedules and a 0.1 % tolerance; B-19 is not the tariff a utility of Net3’s size is on, and it is one teaching network.

A figure from its own output

Paper, code and results

• README and method
• Experiments and results
• Code
• Tests

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Produced with AI assistance (Claude). Results are from the code in this repository and are simulated or stylised unless the abstract says otherwise; nothing here implies affiliation with or endorsement by any lab, researcher or company cited. MIT licensed.