Demand ratchet clauses: how one peak inflates a year of bills

Most facility teams assume a demand charge reflects what they actually used this month. For accounts with a ratchet clause, that assumption is wrong. A ratchet sets a floor under your billed demand based on a peak you hit months ago, so a single spike during a hot afternoon or a one-off equipment test can keep your charges elevated long after the usage is gone.

Ratchets are common in commercial and industrial tariffs, and they are easy to miss because they live in the fine print rather than on the face of the bill. The line item just says demand. What it does not say is that the number was set by last summer, not by this month. Understanding that mechanism is the difference between managing your demand charges and quietly overpaying them.

What a ratchet clause does

A ratchet clause sets a minimum billing demand for each month based on your highest recorded peak over a defined look-back period, typically the prior eleven or twelve months. The tariff picks a percentage of that peak, and you are billed on the greater of your actual demand or that floor. So even if you run light in a given month, your billed demand cannot fall below the ratchet value.

The ratchet percentage varies by utility and rate, but figures in the range of 50 to 90 percent of the highest recorded peak are common. At the high end, a peak set once can hold your billed demand near that level for the better part of a year, regardless of how much you actually cut back.

A worked example

Consider a facility that hits 1,000 kW during a summer heat wave, on a tariff with an 80 percent ratchet at 15 dollars per kW. For the next twelve months, its minimum billable demand is 800 kW, or 80 percent of that peak, no matter how low actual demand runs. If a mild month would otherwise have billed at 400 kW, the ratchet forces it to 800 kW instead. That is 400 extra kW at 15 dollars, or 6,000 dollars of demand charge for that single month, driven entirely by a peak that happened much earlier.

Why the exposure is large

Ratchets sit on top of charges that are already the biggest variable part of a commercial bill. Demand charges can account for 30 to 70 percent of a commercial electricity bill according to national laboratory research, and demand rates commonly run in the range of 10 to 25 dollars per kW each month. A ratchet extends that exposure across every month in the look-back window rather than the single month the peak occurred.

Ratchets mostly affect mid-market and larger accounts, generally those above roughly 50 kW of demand, which is exactly where a single miscalculated peak carries real dollars. The larger the connection, the more a ratchet compounds a bad month into a bad year.

Ratchet designs also vary in ways that change the exposure. Some tariffs apply the percentage to a peak set in any month of the look-back window. Others tie it specifically to the summer or winter season, so a peak set during the utility's own high-cost period carries the most weight. A few apply different percentages to different months. The practical consequence is that two accounts with the same headline peak can face very different ratchet floors, and you cannot assume the worst month is the one that sets your bill without reading the specific clause.

How to spot a ratchet on your bill

The clearest tell is a mismatch between billed demand and actual demand. If your metered demand drops during a slow month but the demand you are charged for holds steady or stays higher, a ratchet is likely in play. Some bills show both an actual and a billed demand value, and the gap between them is the ratchet at work. Others show only the billed figure, in which case you need your interval data to know what your true demand was.

The other place to look is the tariff itself. Ratchet provisions are written into the rate schedule, often under a heading like minimum demand or billing demand, and they specify the percentage and the look-back window. Reading them tells you exactly how long a peak will follow you and how much of it will stick.

• Compare billed demand against actual metered demand month by month, and flag any persistent gap.
• Read the rate schedule for a minimum or billing demand clause, and note the percentage and look-back window.
• Watch for months where usage fell but the demand charge did not.
• Track the peak that set the ratchet, so you know when it will roll off the look-back window.

Managing demand under a ratchet

Because a ratchet anchors on your single highest peak, the priority is preventing that peak in the first place. One avoidable spike, from testing all equipment at once or failing to stagger a morning start-up, can reset the floor for a full year. That makes peak avoidance far more valuable under a ratchet than under a plain monthly demand charge, since the payoff extends across every month in the window rather than one.

Doing that well requires visibility into when peaks occur and how close current operations run to the existing ratchet floor. If a new peak would not exceed the floor anyway, there is less at stake in a given month; if operations are creeping toward a new high, that is the moment to intervene. None of this is possible without clean interval data and a clear record of the peak that set the current ratchet.

There is also a timing dimension worth planning around. Every ratchet floor eventually rolls off as the peak that set it ages out of the look-back window. Knowing the date a high peak will expire tells you when your billed demand can finally reset to actual usage, which matters for budgeting and for deciding when a demand-reduction project will start paying back. A team that tracks the setting peak and its expiry can time interventions to the moment they do the most good, rather than fighting a floor that was about to drop off anyway.

Where clean data comes in

MartinAI collects utility bills and interval data across any commodity and any utility, then extracts billed demand, actual demand, and the associated charges as structured fields. That makes a ratchet visible: you can see where billed demand exceeds metered demand, identify the peak that set the floor, and track when it will roll off. Across a portfolio, that turns a clause buried in dozens of tariffs into a set of numbers you can actually watch.

With that data in hand, your team can feed accurate demand history into whatever peak management or forecasting tools you run, and give accounts payable the evidence to confirm a demand charge is correct before it is paid. The point is not to promise savings, but to make the mechanism legible, so a ratchet stops being a surprise on the bill and becomes a managed line in the budget.