Pre-cooling is one of the simplest demand flexibility strategies for commercial buildings. The physics are straightforward, the implementation is proven, and the results show up in your first billing cycle. But there's a difference between running a pre-cooling schedule and actually optimizing when your building uses power.
Efficiency vs Demand Flexibility
First, let's be clear about what pre-cooling is and isn't. Efficiency strategies reduce how much energy you use. Better insulation, higher-efficiency equipment, LED retrofits. These lower your total kWh consumption.
Demand flexibility is different. It shifts when you use energy, not how much. Pre-cooling doesn't reduce your total cooling load. It moves that load from expensive peak hours to cheaper off-peak hours. Same kWh, different timing, lower bill.
Both matter. But if you've already invested in efficient equipment and a good BMS, demand flexibility is often the next lever with the fastest payback.
The Basic Physics
A building is a thermal battery. The concrete floors, drywall, and furniture all store thermal energy. Cool a building down before peak hours, and it stays comfortable with reduced or zero cooling for 1-3 hours, depending on construction and conditions.
The approach: run HVAC harder during off-peak hours (typically morning) when energy is cheaper and demand charges are lower. Then coast through peak hours (typically 2-7 PM) when rates are highest.
6 AM - 12 PM: Cool to 21°C (2°C below normal setpoint)
12 PM - 2 PM: Maintain at 22°C (normal setpoint)
2 PM - 6 PM: Allow drift to 24°C (HVAC reduced or off)
6 PM onwards: Resume normal operation
Why Occupants Don't Notice
The human comfort zone is wider than most building operators assume. Studies consistently show that occupants can't distinguish between 22°C and 24°C if the temperature drifts gradually. What they notice is rapid changes, like a sudden jump from 22°C to 26°C.
Pre-cooling exploits this. By starting cooler and allowing a slow drift, you stay within the comfort band while shifting when you consume energy. Occupants experience a stable, comfortable environment. Your utility bill reflects a much lower peak demand.
What Your BMS Can Do
Modern building management systems are excellent at what they're designed for: controlling equipment, maintaining setpoints, running schedules, and responding to sensor inputs. If you have a good BMS, you can absolutely program a pre-cooling schedule.
Set your morning setpoint 2°C lower. Program a temperature drift allowance in the afternoon. This works, and many buildings do it successfully. Your BMS investment pays off here.
What Your BMS Can't See
The limitation isn't your BMS itself. It's what information your BMS has access to. A BMS optimizes based on what it knows: temperature sensors, schedules, equipment status. But effective demand flexibility requires information that lives outside the building:
- Weather forecasts: Tomorrow will be 38°C. Should you pre-cool more aggressively today?
- Electricity prices: Real-time rates just spiked. Is it worth coasting an extra 30 minutes?
- Demand charge thresholds: You're 15 kW away from setting a new monthly peak. Should HVAC pause?
- Grid signals: The utility just called a demand response event. Can you participate?
- Other site loads: An EV charger just started a session. Should HVAC back off?
Your BMS sees the building. It doesn't see the grid, the market, or the other loads competing for the same electrical capacity. That's not a criticism. It's just not what BMS systems were built to do.
Where Orchestration Adds Value
An orchestration layer sits on top of your BMS and makes it smarter. Not by replacing what your BMS does well, but by giving it better instructions based on a wider view.
- Predictive pre-cooling: Adjust today's schedule based on tomorrow's weather forecast
- Price-responsive control: Automatically extend coast periods when real-time prices spike
- Demand tracking: Watch your 15-minute interval in real time and shed load before you set a new peak
- Cross-load coordination: Balance HVAC against refrigeration, lighting, and EV charging
- Grid participation: Respond to demand response events and capture incentive payments
The BMS executes. The orchestration layer decides what to execute and when, based on the full picture of building physics, energy costs, and operational constraints.
Equipment: Efficient HVAC, refrigeration, lighting
BMS: Reliable control, scheduling, setpoint management
Orchestration: Weather, prices, demand tracking, cross-load coordination
Each layer makes the layers below it more valuable.
Building Types That Work Best
Pre-cooling effectiveness varies by construction:
- Concrete/masonry buildings: Excellent thermal mass, can coast 2-4 hours
- Steel-frame with concrete floors: Good thermal mass, 1-3 hours
- Light commercial/retail: Moderate thermal mass, 1-2 hours
- Metal buildings/warehouses: Limited thermal mass, 30-60 minutes
Results to Expect
A well-implemented pre-cooling strategy typically delivers:
- 15-25% peak demand reduction from HVAC alone
- 10-20% demand charge savings depending on rate structure
- Zero comfort complaints when implemented properly
- Payback in weeks since it's purely a software/controls change
Add cross-load coordination (HVAC + refrigeration + EV charging) and results compound. The site that can shift 50 kW of HVAC plus 30 kW of refrigeration plus pause EV charging during peaks has far more flexibility than the site optimizing HVAC alone.
The Bigger Picture
Pre-cooling is a starting point, not the destination. Once you can shift HVAC load based on external signals, the same logic applies to refrigeration, lighting, and EV charging. The site becomes responsive to prices, demand thresholds, and grid conditions in real time.
That's where demand flexibility stops being a scheduling exercise and becomes a competitive advantage.