Peak Demand Charges: What They Are and How to Reduce Them

A commercial facility consuming the same total kilowatt-hours two months in a row can see its electricity bill swing by thousands of dollars—because of a single 15-minute interval when too many large loads ran at once. That interval sets the month's peak demand, and demand charges often account for 30–50% of total commercial electricity costs in Ontario, Alberta, and British Columbia.

Understanding demand charges is essential for any Canadian facility manager, operations lead, or CFO responsible for utility budgets. Unlike energy charges that scale with total consumption, demand charges penalize the moment of highest power draw—making them both the most expensive and the most actionable line item on most commercial bills. This guide explains how demand charges work, who they affect most, and six proven strategies to bring them down.

What Are Peak Demand Charges?

Electricity demand charges are fees based on the maximum rate at which your facility draws power from the grid—not the total energy consumed over the billing period. While energy is measured in kilowatt-hours (kWh), demand is measured in kilowatts (kW)—the instantaneous rate of power draw.

Utilities charge for demand because the grid must be built and maintained to handle every customer's peak load simultaneously. A transformer, feeder line, and generation capacity sized for your facility's maximum draw sits idle most of the time—but the utility must recover that infrastructure investment whether you use it or not.

On a typical Ontario commercial bill, you'll see demand charges listed separately from energy charges, often at rates of $8–$18 per kW per month depending on rate class and utility. Alberta and BC commercial rates follow similar structures. Quebec and Manitoba generally structure rates differently, with demand components less prominent for smaller accounts.

How Demand Charges Are Calculated

Understanding the calculation mechanics is the first step to controlling them.

The 15-Minute Interval

Most Canadian utilities measure demand using 15-minute intervals. The meter records total kWh consumed during each interval, then calculates average kW:

Average kW = kWh consumed in interval ÷ 0.25 hours

Example: If your facility consumes 125 kWh during a 15-minute interval, average demand for that interval is 125 ÷ 0.25 = 500 kW. If this is the highest interval in the billing month, your billed demand is 500 kW.

Monthly Maximum Demand

Your utility scans all intervals in the billing period and bills you for the single highest one. It does not matter if that peak lasted the full 15 minutes or resulted from a brief surge—the interval average captures it.

Ratchet Clauses

Many utilities apply ratchet clauses that bill demand based on the highest peak in the current month or a historical period—typically the highest peak in the past 11 or 12 months. A 600 kW peak in July can mean you pay for 600 kW of demand every month through the following June, even if your actual peaks drop to 400 kW in cooler months.

Ontario's Industrial Conservation Initiative (ICI) uses a similar concept at the provincial level—Class A customers' Global Adjustment costs are tied to their share of provincial peak demand during five peak hours, creating a ratchet effect that persists for years.

A single 15-minute interval when multiple large loads start simultaneously can add $500 to $5,000 to a monthly commercial electricity bill—and persist for months under ratchet billing.

Real-World Cost Impact

Consider a 40,000-square-foot commercial building in the Greater Toronto Area with the following profile:

• Monthly energy consumption: 85,000 kWh
• Energy rate (blended): $0.13/kWh → $11,050/month in energy charges
• Peak demand: 350 kW
• Demand charge: $14/kW/month → $4,900/month in demand charges

Demand charges represent 31% of this facility's total electricity cost—despite being determined by a single 15-minute interval. If a morning start-up sequence pushes peak demand from 350 kW to 420 kW, the additional 70 kW costs $980 per month—or $11,760 annually if the ratchet persists.

At an industrial scale, the numbers grow proportionally. A 2 MW manufacturing facility with $16/kW demand charges and 1,800 kW peak pays $28,800 monthly in demand alone. Reducing peak by 200 kW saves $3,200 every month.

Which Businesses Are Most Affected

Demand charges disproportionately impact facilities with high, variable loads that start and stop throughout the day:

• Commercial buildings with large HVAC systems — Chillers, cooling towers, and electric reheat create demand spikes during morning ramp-up and afternoon peak cooling
• Manufacturers — Production equipment, compressors, and motors starting simultaneously during shift changes
• Cold storage and food processing — Refrigeration compressors cycling on in response to defrost schedules and door openings
• EV charging installations — Fleet depots and public charging hubs where multiple vehicles charge concurrently
• Data centres and server rooms — Cooling systems responding to IT load spikes
• Car washes, laundromats, and batch processors — Equipment that draws high power for short durations

Facilities with flat, consistent load profiles—baseload industrial processes running 24/7—face lower demand charge exposure relative to their total consumption because their peak-to-average ratio is smaller.

Strategy 1: Load Scheduling

Load scheduling shifts non-critical energy consumption from periods when demand is already high to off-peak or low-demand periods. The goal is to flatten the demand curve so no single interval exceeds your target threshold.

Practical load scheduling actions:

• Run batch processes, water heating, and ice making during overnight off-peak hours
• Schedule EV and forklift charging to start after 11 PM or stagger charging sessions
• Delay non-urgent equipment start-up until after morning HVAC ramp-up completes
• Use timers and BAS schedules to prevent multiple large loads from overlapping

Load scheduling requires no capital investment beyond programming changes—and can reduce peak demand by 10–20% when applied systematically. See our guide on time-of-use pricing and load shifting for detailed scheduling strategies that reduce both energy and demand costs.

Strategy 2: Building Automation Setbacks

Building automation systems (BAS) control HVAC, lighting, and auxiliary systems on programmed schedules. Optimizing these schedules for demand management—not just comfort—reduces peak draw during critical intervals.

Key BAS demand management techniques:

• Pre-conditioning — Cool or heat the building during off-peak hours (overnight or early morning), then allow temperature drift during on-peak periods when demand charges and TOU rates are highest
• Staged ramp-up — Start air handlers sequentially over 30–60 minutes rather than simultaneously at occupancy time
• Demand limiting — Configure the BAS to shed non-critical loads (decorative lighting, secondary pumps, non-essential ventilation) when demand approaches a preset kW threshold
• Recovery ramp control — After a demand-limiting event, gradually restore loads rather than restarting everything at once

For comprehensive HVAC optimization strategies, see our guide on HVAC energy optimization for commercial buildings.

Strategy 3: Equipment Sequencing

When multiple large motors or compressors start simultaneously, inrush current creates a demand spike far exceeding steady-state operating power. Sequencing ensures only one large load starts at a time, with a delay between subsequent start-ups.

Example: A facility with four 100 HP compressors starting together draws approximately 300 kW inrush. Starting them sequentially with 5-minute delays limits peak to approximately 75–100 kW per interval—a 200+ kW demand reduction from behaviour alone.

Implementation options:

• Programmable logic controllers (PLCs) with interlocked start sequences
• Soft starters and VFDs that reduce inrush current on individual motors
• BAS integration with equipment start-up delays
• Operational procedures requiring manual sequencing during shift changes

Strategy 4: Battery Energy Storage for Peak Shaving

Battery energy storage systems (BESS) discharge stored energy during intervals when facility demand would otherwise exceed a target threshold—effectively "shaving" the peak. The battery charges during low-demand periods and discharges during high-demand intervals.

Economics depend on:

• Demand charge rate — Higher $/kW/month improves battery ROI. Above $12/kW/month, peak shaving becomes compelling for many facilities
• Peak predictability — Facilities with consistent daily peak patterns benefit most; random peaks are harder to shave cost-effectively
• Peak magnitude and duration — Short, sharp peaks (15–30 minutes) are ideal for battery dispatch; sustained high demand requires larger, more expensive systems
• Available incentives — Federal and provincial programs may offset 20–50% of battery installation costs

Typical commercial peak-shaving batteries (100–500 kWh) cost $300–600 per kWh installed. A 250 kWh system shaving 150 kW of peak at $14/kW/month saves $2,100 monthly ($25,200 annually), achieving payback in 5–8 years before incentives.

Strategy 5: Demand Response Programs

Demand response (DR) programs pay commercial customers to reduce load when the grid is stressed—typically during provincial peak hours in summer. Participants receive capacity payments for enrolling and energy payments for curtailing during dispatch events.

In Ontario, the IESO operates multiple DR programs including the Capacity Auction and Operating Reserve. Alberta's AESO and BC Hydro offer similar programs. Industrial facilities with curtailable loads—HVAC, process equipment, backup generation—can earn $50,000–$500,000+ annually depending on curtailable capacity.

DR participation also reduces demand charges directly: curtailing load during grid peak events prevents your facility from setting a new monthly billing peak. For a detailed overview, see our guide on demand response programs for Canadian industrial facilities.

Strategy 6: Real-Time Demand Monitoring and Alerts

You cannot manage demand you cannot see. Real-time monitoring displays current kW draw updated every 1–15 minutes, enabling operations teams to take action before a billing peak is set.

Effective demand monitoring includes:

• Threshold alerts — Notifications when demand approaches 85–90% of your monthly peak target, giving a 15-minute window to shed load
• Anomaly detection — Flags when demand exceeds weather-normalized baselines, indicating equipment malfunction or schedule override
• Peak prediction — Forecasting models that anticipate demand based on current trajectory, weather, and historical patterns
• Cost simulation — Modeling the dollar impact of current demand trajectory against rate schedules and ratchet history

Energy Wiz provides mobile smart alerts for threshold and anomaly detection, plus Intelligence Hub forecasting and cost simulation to anticipate peaks before they occur. Combined with interval data analysis, teams using real-time demand monitoring reduce peak demand by 10–25% in the first year. Learn more in our real-time energy monitoring guide and energy forecasting and predictive analytics overview.

Peak Demand Reduction Strategy Comparison

Conclusion

Peak demand charges are the hidden driver behind many commercial electricity bill surprises—and the most actionable cost component for facilities willing to monitor and manage their load profile. A single 15-minute interval can cost thousands of dollars per month and persist for a year under ratchet billing.

Start by analyzing your interval demand data to identify when and why peaks occur. Implement load scheduling and equipment sequencing immediately—these require no capital investment. Add real-time monitoring with threshold alerts so your team can respond before peaks are set. Evaluate battery storage and demand response programs once you understand your peak patterns and their dollar impact.

Monitor demand in real time, simulate cost scenarios, and set smart alerts with Energy Wiz—Canada's mobile energy management platform for commercial and industrial teams.