The Changing Ontario Energy Market
Ontario’s electricity system is in the middle of a significant transformation. Rising electrification, volatile demand patterns, and growing participation in demand response programs are making it increasingly difficult to predict when the grid will experience its highest system peaks.
For decades, the Independent Electricity System Operator (IESO) has relied on demand forecasting to balance supply and demand, set pricing, and allocate costs such as the Global Adjustment (GA). But in 2025, using IESO’s forecasts for peak forecasting has become dramatically less reliable.
For Ontario’s largest commercial and industrial (C&I) energy users, this matters because the top five coincident peaks determine a huge portion of next year’s GA costs. Missing just one of those five peaks can cost millions.
This is where precision in peak forecasting becomes a true competitive advantage.
Ontario is also shifting toward becoming a double-peaking market, meaning both winter and summer electricity demand will reach similarly high levels. Historically, Ontario has been a summer-peaking system, but by the 2030s demand growth from industrial expansion, data centers, and electrification will make winter peaks just as significant. The IESO forecasts this dual-peak future and is proposing new clean supply resources to meet it. For large energy users, this shift underscores the importance of partnering with a market leader for global adjustment peak forecasting.
Figure 1: Ontario’s Net Annual Peak Demand Forecast (2026–2050), Source: IESO, 2025 Annual Planning Outlook
Why Global Adjustment Cost Matters for Large Energy Users
The Global Adjustment charge accounts for the costs of building and maintaining Ontario’s electricity system, including investments in generation and conservation. For C&I facilities with demand greater than 2 MW, participation in the Industrial Conservation Initiative (ICI) allows them to reduce GA costs by curtailing demand during the top five system peaks each year.
The math is simple:
- Hit more peaks → Lower GA costs next year.
- Miss peaks → GA costs rise dramatically.
But the execution is anything but simple. Predicting the exact hours of Ontario’s top five coincident peaks requires not just weather and load forecasting, but also accounting for how demand response participation and operational shifts across the province are reshaping demand in real time.
Ontario’s Market Renewal Program and the Role of Global Adjustment
Ontario’s electricity sector is undergoing its Market Renewal Program (MRP), a multi-year effort led by the IESO to improve efficiency and enhance competition in the province’s wholesale market. While MRP will introduce changes such as a single-schedule market and enhanced day-ahead processes, one constant remains: the Global Adjustment is here to stay. As outlined in our recent article on the Market Renewal Program, the GA charge will continue to represent a major portion of costs for large energy users.
This is an important reality for Ontario’s C&I facilities. Even with evolving market structures, GA remains the single largest driver of electricity expenses. That means peak management strategies and accurate forecasting will remain the most effective levers for reducing costs. In other words, while the market around it is modernizing, the incentive to capture top peaks and minimize GA costs is not going anywhere.
2025: The Most Difficult Year Yet for GA Forecasting
This year, two unique factors have made peak forecasting more challenging than ever before:
- Demand Response Growth:
Demand response (DR) has grown in participation and impact. On high load days, DR activations can flatten the curve so much that peaks either disappear or shift to new times of day not explained by temperature or grid conditions. The result? No two peak days look alike. - IESO Data Inconsistencies:
The IESO has acknowledged providing inaccurate load data on certain days without full transparency on when or how it will be remedied. Many market participants and service providers build their forecasts primarily around IESO-provided data. This year, that reliance has led to widespread misses of coincident peak events.
Together, these factors have made 2025 a year in which traditional forecasting approaches have struggled, leaving many large facilities frustrated with underperformance.
Proven Results in a Tough Year
Despite these challenges, Peak Power’s forecasting has continued to deliver strong, measurable results for Ontario clients.
- 4 of 5 Top Peaks Accurately Predicted (within a strict 2-hour window)
- 2 of those were #1-hour predictions — meaning if facilities only had a single discharge hour, they still would have caught the peak
- 25 calls were made to achieve this precision — carefully balancing the need for accuracy with operational efficiency
Importantly, we don’t “move the goalposts.” Some service providers claim peak hits if they fall within a 3–4 hour window, but we know that’s not realistic for facilities with 2-hour batteries or limited curtailment windows. Our standard is clear: a forecast is only counted as a hit if the actual peak hour is inside our top two predicted hours of the day.
Why Accuracy Matters to Your Business
For facilities which are large energy consumers, forecasting accuracy isn’t just about numbers — it translates directly into financial performance.
- Maximized Savings: Every accurately captured peak results in Global Adjustment cost reduction for the following year, often representing millions in avoided costs.
- Reduced Risk: Narrow 2-hour precision means batteries and curtailment strategies are deployed efficiently, reducing wear-and-tear and unnecessary operational disruption.
- Operational Certainty: Confidence in forecasts allows energy managers and CFOs to plan with clarity, even in an uncertain grid environment.
What Sets This Forecasting Apart
While many competitors rely heavily on IESO forecasts and broad performance windows, Peak Power takes a fundamentally different approach.
- Independent Forecasting: We don’t rely solely on IESO data, which has proven unreliable this year. Instead, we use multiple proprietary data sets and models to build forecasts that remain resilient even when official data is wrong.
- Tighter Accuracy Standard: We only count a “hit” if the peak occurs within our 2-hour prediction window. This matters because it matches the operational reality of facilities with 2-hour batteries or curtailment programs — giving you a more honest measure of performance.
- Enhanced Data & Constant Innovation: Our forecasting team integrates enhanced weather models, operational signals, and proprietary analytics. We continually evolve to adapt to Ontario’s fast-changing market conditions.
This commitment to independence and precision is why our clients consistently achieve stronger GA reductions compared to facilities that rely on looser or less resilient forecasting methods.
Customer Benefits: What This Means for Your Facility
If you are a large Ontario energy user with more than 2 MW of peak load, the benefits of precision forecasting translate directly to your bottom line:
- Lower Global Adjustment Costs: Capture more of the top five peaks and lock in significant year-over-year savings.
- Optimized Asset Use: Batteries, backup generation, or load curtailment programs are deployed strategically — not wastefully.
- Competitive Edge: Reduced energy costs improve operating margins and free up capital for reinvestment in core business operations.
- Peace of Mind: Reliable forecasts mean you can focus on production and growth, not chasing unpredictable system peaks.
Looking Forward: Preparing for an Uncertain Future
Ontario’s electricity system is only going to get more complex. Load growth is outpacing new supply, demand response is expanding, and electrification of transportation and industry will reshape load curves in unpredictable ways.
In this environment, accuracy and adaptability in forecasting will define winners and losers in GA cost management. Facilities that rely on outdated models or broad 3–4 hour windows risk overspending and underperforming.
By contrast, facilities that adopt precision-driven, independent forecasting strategies will not only minimize costs but also position themselves as leaders in sustainability, resilience, and competitiveness.
Take Action for Global Adjustment Cost Reduction
Global Adjustment costs don’t have to be unpredictable or uncontrollable. With the right forecasting partner, large energy users in Ontario can take control of their GA costs, reduce risk, and unlock measurable financial value — even in the most challenging years.
At Peak Power, we’re proud to deliver results that speak for themselves. Precision, adaptability, and customer savings are at the core of everything we do. And as Ontario’s grid evolves, we’ll continue to innovate to keep our customers ahead of the curve. Or, should we say, ahead of the “load curve.”
Ready to reduce your Global Adjustment costs? Contact us today to book a discovery call.