Every refrigeration system in your building is also a battery. Not an electrical battery, a thermal one. And understanding how to use it changes what's possible with demand flexibility.
The Physics of Cold Storage
A walk-in freezer at -18°C contains an enormous amount of stored "coldness." If you turn off the compressor, the temperature rises, but slowly. The frozen goods, the walls, the air itself all act as thermal mass, absorbing heat gradually.
How slowly? A well-insulated walk-in freezer might rise 1-2°C per hour with the door closed. That means you can turn off the compressor for 2-3 hours and still stay well within food safety limits. That's 2-3 hours of zero energy consumption from a load that typically runs 40-60% of the time.
Walk-in freezer (-18°C): 2-4 hours
Walk-in cooler (2-4°C): 1-2 hours
Display refrigerator: 30-60 minutes
Open cold cabinet: 15-30 minutes
Pre-Cooling: Banking Coldness for Later
The real power comes from pre-cooling. Before a peak demand period, run the refrigeration harder than necessary. Pull the freezer down to -22°C instead of -18°C. Cool the walk-in to 1°C instead of 3°C.
Now you've banked extra thermal mass. When peak pricing hits or you need to shed load for EV charging, you can coast for even longer. The system absorbs energy when it's cheap and releases it when it's expensive. Exactly like a battery, but using physics you already own.
The Supermarket Example
A typical supermarket runs 80-150 kW of refrigeration across freezers, coolers, and display cases. Traditional thinking says this load is fixed because the food needs to stay cold.
But with thermal mass orchestration, 30-50% of that load becomes flexible. Pre-cool the back-of-house freezers and walk-ins in the morning. Coast them during the afternoon peak. The display cases have less flexibility, but even they can shift by 15-20 minutes when orchestrated properly.
Result: 30-50 kW of flexible capacity from refrigeration alone. Add HVAC and lighting, and you're looking at 60-100 kW of demand flexibility in a single store.
Why This Matters for EV
Fuel stations and convenience stores adding EV chargers face a common problem: the grid connection wasn't sized for 150 kW fast chargers on top of existing load. But these same sites have refrigeration running 24/7.
Orchestrate the refrigeration thermal mass with EV charging, and suddenly the maths works. When a vehicle plugs in, the cold cabinets coast on their thermal buffer. When charging completes, refrigeration catches back up. The grid connection sees a steady load instead of a spike.
The Constraints That Matter
Thermal mass flexibility isn't unlimited. Food safety sets hard boundaries: freezers can't rise above -15°C, coolers can't exceed 5°C. Door openings during business hours accelerate temperature rise. Overnight, when stores are closed, flexibility increases dramatically.
The orchestration layer needs to understand these constraints in real-time: current temperatures, door states, ambient conditions, and safety margins. Get it right, and you unlock significant flexibility. Get it wrong, and you spoil inventory.
The Bottom Line
Refrigeration isn't just a load. It's a thermal battery. The sites that learn to orchestrate this physics will have flexibility their competitors don't, at zero additional capital cost. The coldness is already there. You just need to use it smarter.