By Tamika Brooks · Updated August 29, 2026 · 6 min read
Short answer
Texas summer peaks occur on hot weekday late afternoons, when air conditioning is at its highest. In commercial buildings cooling is often among the largest electric loads, so shifting or trimming it through scheduling, setpoint control, demand response and thermal storage can reduce demand charges and ease grid stress.
ERCOT’s demand peaks usually come on hot summer weekday afternoons, when air conditioning runs hardest across homes and businesses. In a commercial building, cooling is often one of the largest electric loads, so how and when chillers and rooftop units run matters for both the utility bill and the grid. The main tools are scheduling, setpoint control, demand response and thermal storage.
Why do Texas summers produce peak demand?
Peak demand follows temperature and occupancy. Late afternoon combines the hottest outdoor air with solar heat still in building envelopes and occupied spaces. Population and business growth in Central Texas add load year after year. ERCOT publishes demand and forecasts, so check its current data for recent records and outlooks.
How much of a building’s load is cooling?
It varies by building type, age, envelope and use. In offices, schools, retail and healthcare in a hot climate, cooling is typically one of the biggest electric end uses, and it is the one most correlated with peak hours. A sub-metered chiller plant or an energy audit gives the real number for a specific site, far better than rules of thumb.
What are the basic ways to reduce peak cooling load?
- Pre-cool. Lower the temperature slightly in the morning, then relax setpoints during the peak window, within comfort limits.
- Stage equipment. Sequence chillers and rooftop units to avoid all starting at once.
- Reset temperatures. Raise chilled water supply or reduce static pressure when loads are light.
- Use variable speed. VFD compressors and pumps cut part-load energy.
- Maintain equipment. Dirty coils and low charge increase kW; see the chiller maintenance checklist.
- Improve the envelope and controls. Shading, glazing and a tuned building automation system reduce the load itself.
How do demand response and thermal storage help?
Demand response pays or credits customers who cut demand when the grid is tight. Cooling is a common source of curtailable load because buildings can tolerate small temperature drift for short periods. Program availability and terms change, so check with your retail electric provider and ERCOT.
Thermal storage makes ice or chilled water at night or midday and discharges it during the peak. See thermal energy storage explained.
| Option | What it does | Typical fit |
|---|---|---|
| Pre-cooling and setpoint shift | Moves load by hours | Offices, schools |
| Demand response | Cuts load on call | Sites with controllable HVAC |
| Chilled water or ice storage | Shifts chiller run time | Large plants with demand charges |
| Equipment staging | Lowers peak kW | Multi-unit plants |
What should a facility manager check first?
- Interval meter data to find peak hours and demand charges.
- Chiller and RTU performance against nameplate; see chiller efficiency.
- Control sequences and schedules that may be outdated.
- Whether the building can ride through brief setpoint changes.
- Whether any demand response programs fit your utility or provider.
What low-cost steps help before a summer peak?
Before spending on new equipment, check the basics in the spring.
- Clean the heat-rejection surfaces. Dirty condenser coils raise head pressure and power use. The air-cooled condensers article explains what affects performance.
- Verify setpoints and schedules. Buildings often cool unoccupied space because a schedule was never updated.
- Check controls. Poor staging of multiple chillers is a common hidden cost; see chiller plant control basics.
- Review the demand bill. Knowing when your monthly peak occurs tells you what to shift. Demand charges and chiller scheduling walks through it.
- Plan maintenance ahead of the season. A preventive maintenance plan scheduled before June is cheaper than a failure in July.
None of these require new capital, and together they often make the difference between a plant that holds setpoint on the hottest afternoon and one that does not. Record what you changed so next year’s comparison is meaningful.
Frequently asked questions
When does ERCOT usually peak in summer?
Typically on hot weekdays in the late afternoon to early evening. Exact timing and levels change each year, so see ERCOT’s published data.
Does thermal storage save energy?
Mostly it shifts energy to cheaper or cleaner hours and cuts peak demand. Net energy can be flat or slightly higher, while cost and grid stress go down.
Is pre-cooling safe for occupants?
Yes when done within comfort limits and with good controls. Start with small adjustments and monitor space conditions.
SpecServis engineers in Ukraine have worked on chiller and refrigeration systems, and we are planning to enter the Central Texas market. If you work on commercial cooling and energy, see our open positions or partnership options.
