Demand Management: The Smartest Way to Lower Your Electric Bill
You don't have to use less electricity. You just have to use it smarter.
What Are Demand Charges — and Why Are They Growing?
Most homeowners understand kilowatt-hours (kWh) — that's how much total electricity you consume. But if you're on a time-of-use demand rate, your utility also measures kilowatts (kW) — that's how much electricity you consume at once during the peak window.
Your utility reads your meter in 15-minute intervals. The single highest 15-minute reading in the entire billing period becomes your "peak demand" — and you're charged a per-kW demand fee on that number for the whole month.
Here's why this matters: A home that averages 5 kW of demand but spikes to 12 kW for one 15-minute period pays demand charges on 12 kW all month long.
Utilities are investing billions in grid infrastructure. Rates increase year over year. More homes are adding large electrical loads — EVs, heat pumps, pool equipment, hot tubs — that create bigger spikes. Demand-based rate plans are rolling out to more residential customers as utilities try to flatten their own grid peaks.
The trend is clear: demand charges will only become a bigger part of your bill.
Wally's Hamburger Stand
Wally ran a hamburger stand with 20 seats. Every day at noon, 60 customers arrived for lunch. Wally had a peak demand problem.
He told his customers: "If you all insist on eating at noon, I'll have to build a stand three times bigger, install a grill three times as wide, hire three times more help, put in three times more seats — and the hamburgers will cost three times as much."
"But," Wally said, "if 20 of you come at 11:30, 20 at noon, and 20 at 12:30, I can serve all of you by spreading out the demand and keep selling hamburgers at the lowest possible cost."
Advanced Microcomputer Technology. Simple Results.
The Energy Sentry 9388A uses the "store/defer" principle. Many residential loads contain thermal storage — meaning they hold heat or cold and can be briefly cycled off without affecting comfort.
- Air conditioners — can be cycled for short intervals while your home stays cool
- Water heaters — massive thermal storage; water can be heated at any time
- Pool pumps & heaters — can be deferred for brief periods without impact
- Clothes dryers — can pause and resume without affecting the cycle
- EV chargers — can be shifted to optimal windows automatically
- Hot tubs & spas — large thermal mass, ideal for deferral
The 9388A's microcomputer monitors your total electrical load in real time through current transformers mounted on your service mains. It calculates the rate at which you're approaching your set demand limit and sheds loads in priority order: least important loads shed first, most important loads shed last.
When loads are restored, it reverses: highest priority comes back first, lowest priority last.
With the proper combination of load control and demand limit — set with assistance from a certified professional — you won't even notice the controller is running. But you'll notice the savings on every bill.
What Changes After Installation
| Before Energy Sentry | After Energy Sentry | |
|---|---|---|
| Daily Demand Range | 1.0 kW – 18.0+ kW | Stabilized at ~5–7 kW |
| Monthly Demand Charges | $100–$200+ | $20–$60 |
| Total kWh Consumed | Same | Same |
| Comfort Level | Same | Same |
| You Notice It? | Every month on the bill | "I forget it's there" |