Heat Emergency Operations for Ohio Business Facilities

Ohio market insight · Weather & resilience

Updated September 27, 2026Ohio Commercial Energy editorial teamHow we review content Book a free 15-min bill review

The short answer

A grid heat emergency asks two things of a facility at once: use less power in the late afternoon, and be ready if the power goes out anyway. The facilities that handle it well decide in advance — which loads are critical, which can be shed, who has authority to shed them, how to pre-cool, and how to restart after an outage without creating a new demand spike. In PJM, rotating outages are a last resort and typically last 15–60 minutes per circuit, but local transmission emergencies can cut power for much longer, as central Ohio saw in June 2022.

This page is the facility operations plan. For what each PJM alert means and when to act, see PJM alerts and what to do; for using the same hours to lower your capacity tag, see the PLC playbook; for broader continuity planning, see energy resilience and contingency planning; and for winter events, see cold-snap emergency planning.

What recent heat emergencies looked like

July 2, 2026: PJM's load hit about 168,158 MW, a new all-time record, with the region's average temperature at 97°F. Between 18,100 and 19,400 MW of generation was on forced outage over July 2–4. PJM deployed about 6,100 MW of demand response, the Department of Energy issued two emergency orders, and large loads with backup generators were warned they might be asked to use them. Service was maintained.
June 23–25, 2025: Load reached 160,526 MW, the highest since 2011; PJM declared an Energy Emergency Alert Level 1 and called demand response across the footprint.
June 14–16, 2022: After severe storms damaged transmission lines, PJM directed AEP Ohio to shed load in the Columbus area. PUCO staff counted about 283,000 customers affected by the forced load shedding, with some interruptions lasting many hours — and found customers got very little warning.

The pattern: region-wide shortages are usually handled with demand response and emergency procedures, but local transmission problems during extreme weather can produce long, poorly signaled outages.

Before summer: the critical-load list

Build a one-page list for each site and keep a printed copy at the main electrical room.

Load category	Examples	During a peak alert	During an outage
Life safety	Fire alarm, emergency lighting, egress, elevators, medical equipment	Never curtail	Must be on backup or battery
Product and inventory	Refrigeration, freezers, temperature-controlled storage, process cooling	Pre-chill; limit door openings; avoid defrost during peaks	Keep doors closed; move to backup if available
IT and communications	Servers, network, phones, point of sale, security	Keep on	UPS for orderly shutdown or ride-through to generator
Comfort cooling	Rooftop units, chillers	Pre-cool, then allow setpoints to drift within limits	Protect staff first (see heat safety below)
Deferrable	EV and forklift charging, water heating, batch processes, washdowns, decorative lighting	Shift out of 2–7 p.m.	Off

Next to each load, note its circuit or panel, whether it's on backup power, and who may switch it.

Backup power readiness

Test under load, not just at idle. A generator that starts but trips when the building transfers doesn't help. Test the transfer switch, and do it in the morning or in spring — not on a hot afternoon when the retransfer adds grid load.
Fuel and runtime. Know hours of runtime at expected load and your refill arrangement; suppliers get busy during regional events.
UPS batteries. Check runtime against the time it takes to start a generator or shut systems down cleanly.
Permits. Many generators are permitted for emergency use only. Running one to cut costs or join a program can require different permits; check with your environmental consultant before promising it to anyone. For common failure points, see backup power mistakes.

During a heat alert: pre-cooling and staffing

Pre-cooling uses the building as a thermal battery: cool the space somewhat below normal during the morning and early afternoon, then let the temperature drift up during the late-afternoon peak with fewer compressor stages running. It works best in buildings with heavy construction and good envelopes, and poorly in lightly built spaces or those with high internal heat, like kitchens. Set limits before the day — the highest space temperature you'll allow, humidity limits, and who can override. Test the sequence on a normal hot day first so the emergency isn't the first trial.

Refrigeration can be pre-chilled to its low setpoint before the peak window, with defrost cycles scheduled outside it.

Staffing:

Name a lead for each shift with authority to shed load and to call the outage plan.
Keep a current contact sheet for your utility account representative, electrician, generator vendor, refrigeration contractor and, if enrolled, your demand-response provider.
Brief supervisors on which loads can't be switched off.

Heat safety for staff comes first. OSHA's guidance centers on water, rest and shade, gradual acclimatization for new workers, and training supervisors to recognize heat illness. Shedding comfort cooling in a warehouse or kitchen is only acceptable within those limits.

Preparing for a rotating or local outage

Know your utility's process. In a PJM-directed load shed, PJM sets the amount and your utility chooses which circuits to interrupt, in rotation. Plan as if yours could be included — AEP Ohio has said it can't reach every customer before a rolling outage, so watch its texts and social posts.
Protect equipment. Surge protection on sensitive electronics; a checklist for shutting down motors, compressors and production lines in order.
Protect inventory. Federal food-safety guidance says an unopened refrigerator keeps food safe for up to about four hours and a full freezer about 48 hours. Commercial kitchens should follow their health department's rules and log temperatures.
Keep communications independent of building power. Charged phones, a battery radio, and a way to reach staff who aren't on site.
Plan the restart. When power returns, bring loads back in stages — lighting and controls, then refrigeration, then HVAC, then production and charging. Restarting everything at once can set a new monthly demand peak, and on schedules with a ratchet that peak can raise demand charges for months. See how to lower peak demand charges.

After the event

Record what was shed, when, and how much the meter showed; compare against interval data from your utility's portal.
Check whether the event set a new monthly demand peak.
If you're on an index or pass-through supply product, check the invoice for the event days — real-time wholesale prices can spike during emergencies. Fixed-price contracts absorb that.
Update the critical-load list and pre-cooling limits with what you learned.

The same afternoons carry a price as well as a reliability risk: for the capacity prices that make PJM's peak hours expensive, see PJM capacity auction results, capacity bill math and the 2025 case study.

FAQ

How long do rotating outages last in PJM?

PJM describes rotating interruptions as generally about 15 to 60 minutes per area. Outages caused by local transmission damage can last much longer.

Can my business be exempt from rotating outages?

Don't count on it. Your utility decides which circuits to rotate, so ordinary commercial accounts should plan as if they could be interrupted, with little or no notice.

Is pre-cooling worth it?

It's the cheapest way to cut late-afternoon cooling load, provided you set comfort and humidity limits in advance and test the sequence on a normal hot day first.

Should we run our backup generator during a heat alert to save money?

Not without checking its air permit. Many generators are permitted for true emergencies only, and using them otherwise can create compliance problems.