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Part 4 of 7 · Utility bill watcher series ~5 min read

How a change gets reported

Most cost-monitoring tools report that a bill went up. That is the least useful possible sentence, because the person reading it now has to do the work of finding out why, which is the work they did not have time for in the first place. This system’s messages start from the answer.

Key takeaways

  • The message names which of the three numbers moved, and says the other two did not.
  • Usage movement is an operational message; rate movement is a commercial one.
  • Comparison is against the same period last year, normalised per day.
  • Contract end dates produce their own message, ninety days out, before anything moves.
  • A message carries a one-tap “expected, this is why” that suppresses the same finding.

Three different messages

How a utility bill change is reported, and to whomThree boxes across the top outside the AWS account. Site manager, who fields usage questions. Whoever buys, who fields rate questions. And History, which receives every bill whether or not anything moved. Inside the account, three components. Usage compare, which works per day against the same period last year. Rate compare, which works against the contract. And the Message builder, which names what moved and explicitly says what did not. Arrows show usage findings going to the site manager, rate findings going to whoever buys, and every bill going to history regardless. A note says two of these go to different people and getting that right is most of the design.AWS ACCOUNTSite managerusage questionsWhoever buysrate questionsHistoryeverything, alwaysUsage compareper day, vs last yearRate comparevs the contractMessage buildernames what moved,and what did notusage up 57%rate off contractevery bill, movedor notTwo of these go to different people. Getting that right is most of the design.
Fig 1. Who hears what. A usage message and a rate message go to different people and cause different actions, so the system routes them separately rather than sending one person everything.

The usage message

What it says, in order

  • Which meter, in words. “Hitchin electricity.”
  • The number and the comparison. “6,240 kWh this period, up 57% on the same period last year (3,970).”
  • What did not move. “Unit rate and standing charge are unchanged and match the contract.” This sentence is the point — it converts a cost question into a site question.
  • The per-day figure. “201 kWh a day against 128 last year.” Billing periods vary by several days and comparing totals without normalising produces regular false alarms.
  • One button. “Expected — here’s why”, which records a reason and suppresses the same finding for that meter for a period.

The rate message

Shorter and more urgent, because the action is a phone call and the clock is running. “Hitchin electricity: unit rate 39.2p against a contracted 24.1p. The contract on record ended 30 June.” There is no ambiguity about what happened and no investigation to do; a fixed-term contract ended and the supply rolled onto a variable rate, which is the single most expensive thing that routinely happens to a small business’s energy bill and the single easiest to miss.

The message that arrives before anything moves

The best version of the rate message is the one sent ninety days before the contract ends, when there is still time to do something. It needs no bill at all — just the meter list and a scheduled sweep.

How an approaching contract end is reported ninety days outA horizontal row of five boxes. T minus ninety days: a contract end is approaching. What you pay now: taken from the last bill. Annual usage: taken from your own history. One message: sent to whoever buys energy. T minus thirty reminder: sent if nothing has changed. A note says the message carries your annual usage, which is the number a broker will ask for first.THE CONTRACT-END MESSAGET-90 dayscontract end approachingWhat you pay nowfrom the last billAnnual usagefrom your own historyOne messageto whoever buysT-30 reminderif nothing changedIt carries your annual usage, which is the number a broker will ask for first.
Fig 2. The contract-end sweep. It is the only message this system sends that is not caused by a bill, and it is probably the one that saves the most money.

Attaching the annual usage figure is a small thing that removes a real obstacle. The first question any energy broker asks is how much you use, and the reason renewals get left is that finding out means digging out twelve bills. Having it in the message turns a two-hour job into a five-minute one, which is the difference between it happening and not.

Next: what the accumulated history is actually for.

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