Three different charges on a Fortis commercial invoice are billed against three different kilowatt figures. Knowing which is which is what decides whether shaving your peak changes anything.
Full detail below.
A demand-billed commercial account in this territory does not carry one demand charge. It carries several, and they do not all respond to the same thing. This is the single most useful table for anyone trying to work out why their invoice behaves the way it does.
| Charge | Billed against | Responds to peak shaving? |
|---|---|---|
| Customer charge | Fixed, per day | No |
| Energy charge | Consumption, per kWh | No, solar and efficiency move this |
| System usage charge | Highest metered demand in the period | Yes, directly |
| Transmission capacity charge | Contracted demand | No, not without renegotiation |
| Local facilities charge | Contracted demand | No, not without renegotiation |
Structure shown by charge type and billing determinant. Current per-unit rates for your rate class are published in the FortisAlberta rates, options and riders schedule and change periodically.
Source: Utilities Consumer Advocate, Understanding demand charges. Billing determinants and rate minimums are set in each distributor's approved tariff and change over time. Confirm the figures on your current rate schedule before relying on them.
Billing demand will not fall below 3 kW in this territory regardless of how little power the site draws. For most commercial accounts that floor is academic. It matters when sizing a system, because it marks the point at which further shaving stops producing any return.
Some rate designs carry a ratchet, holding billing demand at a percentage of an earlier peak. The Utilities Consumer Advocate illustrates the mechanism at 85%: a 50 kW peak establishes a 42.5 kW floor on later bills. Under that structure a single unmanaged interval is not a one month event. It sets a floor under many subsequent invoices, which is what makes prevention worth considerably more than it first appears.
On a completed project at a grain operation served by this distributor, demand charges made up 43.7% of a $75,389 annual bill. Storage cut the annual demand line by roughly 20%. The capacity-billed portions of the invoice did not move, exactly as the table above predicts. Full case study.
FortisAlberta bills the system usage charge against the highest metered demand recorded in the billing period. The transmission capacity charge and the local facilities charge are billed against contracted demand instead, which is an agreed capacity level rather than what you actually drew. A rate minimum of 3 kW applies, and some rate designs also carry a ratchet based on historical demand.
Rate 63 is one of the general service rate classes in the FortisAlberta tariff where demand billing applies. If your account sits on a demand-billed class, your invoice will separate a demand component from the energy component, and the determinants above decide which kilowatt figure each charge is calculated from. Check your bill or your rate schedule to confirm which class you are on.
Highest metered demand is the largest interval reading in the billing period and it sets the system usage charge. Contracted demand is an agreed capacity level and it sets the transmission capacity and local facilities charges. Because they drive different lines, cutting your metered peak can lower one part of the bill while leaving the capacity charges completely unchanged.
It reduces the portion billed against highest metered demand, and it does so in the same billing period. It does not directly reduce charges billed against contracted demand. Lowering those requires renegotiating the contracted level with the distributor, using a sustained record of lower peaks as the evidence.
The most common answers are a ratchet carrying a previous peak forward, a contracted demand level set for load you no longer run, or a single unusual interval that set a new peak. None of these are visible from monthly totals alone. Interval data is what separates them.
