Restaurants: two spikes a day, every day

The load profile

A restaurant's electrical curve has two mountains on it and they are in the same place every day.

Morning prep brings on the cook line. Ovens, fryers, griddles, holding cabinets, warmers, all of them heating from cold to setpoint simultaneously. Then the lunch rush stacks HVAC on top, because the dining room fills with people and the kitchen is throwing off heat that the rooftop units have to remove. Then a quieter afternoon. Then dinner does it again, and dinner usually lands squarely inside the utility's on-peak window.

Underneath both mountains is a substantial base load that never stops: walk-in coolers and freezers, reach-ins, ice machines, and exhaust hood fans running whenever the line is hot.

That base load is what makes restaurants a more nuanced case than churches. Load factors typically run higher, in the 35 to 50 percent range, which is a reasonable candidate rather than a slam dunk. The interval data tells you which side of the line a specific location falls on.

Why it is a good candidate

Three reasons.

The peaks are large and they are stacked. Electric cooking equipment, HVAC and refrigeration all reach their highest draw within the same hour, and none of them coordinate. That stacking is exactly what a demand controller is built to unstack.

The peaks are predictable. Unlike a church that has an unusual event calendar, a restaurant does roughly the same thing at roughly the same time seven days a week. Predictable loads are easier to sequence well.

And there is real thermal slack in equipment that people assume has none. A holding cabinet that has reached temperature does not lose it in ten minutes. A walk-in cooler at 36 degrees full of product is a large thermal mass that drifts extremely slowly with the door closed. Those are deferrable in ways the operator would never notice.

The multi-location angle matters commercially. A franchise operator running eight locations on similar rate structures is looking at eight similar projects, and results from the first one tell them what the other seven will do.

Which loads get controlled

Refrigeration compressors first, and this is the counterintuitive one. Walk-ins and reach-ins hold temperature through short interruptions because of the mass of product inside them. Compressors get rotated so only some run at a time, with minimum on and off timers protecting the equipment. Product temperature does not move.

HVAC rooftop units next, grouped and rotated the same way a church's are.

Electric water heating, which in a restaurant is large because of dish machines and sanitizing requirements. Booster heaters get evaluated carefully and are often excluded, because health code sanitizing temperatures are not negotiable.

Some electric cooking equipment, selectively. Holding cabinets, warmers and proofers have thermal mass and tolerate deferral. Fryers and griddles during active service generally do not, and they get high priority or get excluded entirely.

What does not get controlled: anything that affects food safety or ticket times. That line is drawn during the site inspection with the operator, in writing.

What the buying process looks like

Interval data first, and for restaurants it is worth pulling at least a summer month and a winter month, because HVAC changes the shape considerably.

Tariff analysis with attention to whether demand is billed 24/7 or on-peak only. Restaurants with 24-hour refrigeration base load do differently under those two structures.

Site inspection with the kitchen manager present, not just the electrician. We need somebody who knows what happens at 6:45 p.m. on a Friday to tell us which equipment is untouchable. Every commercial equipment list is built from scratch for the specific site, and the price follows from that list.

For multi-location operators, the sensible approach is a pilot at one representative location, verified against actual bills for two or three billing periods, before rolling out.

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