What Is a Demand Charge and Why Is It on Your Bill?

If you have ever looked at your commercial electricity bill and wondered why it is so much higher than the per-kWh rate would suggest, there is a good chance the answer is demand charges. For many Texas businesses, demand charges account for 30% to 70% of the total electricity bill — yet most business owners have never heard of them until they see the number.

This guide explains what demand charges are, how they are calculated, why they exist, and what you can do to manage them.

Energy Charges vs. Demand Charges

Your commercial electricity bill has two main components, and understanding the difference between them is essential:

Energy charges measure how much total electricity you consumed during the billing period. This is the per-kilowatt-hour (kWh) rate that most people focus on. If you used 50,000 kWh in a month at $0.08/kWh, your energy charge is $4,000. This is the volume of electricity you consumed.

Demand charges measure the highest rate at which you consumed electricity at any single point during the billing period. This is measured in kilowatts (kW), not kilowatt-hours. It reflects the peak load your building placed on the grid — the maximum amount of power you drew at one time. If your peak demand was 200 kW and your demand rate is $10/kW, your demand charge is $2,000.

Think of it this way: energy charges are like paying for the total gallons of water you used in a month. Demand charges are like paying for the size of the pipe needed to deliver water at your peak usage moment. Even if you only turned on every faucet simultaneously for fifteen minutes, you still needed that large pipe — and you pay for it.

How Demand Charges Are Calculated

Your TDU (Transmission and Distribution Utility) measures your electricity usage in 15-minute intervals throughout the billing period. At the end of the month, they identify the single 15-minute interval where your average power draw was highest. That peak — measured in kilowatts — becomes your billed demand for the month.

Here is a concrete example. Suppose your business operates a restaurant. For most of the day, your kitchen equipment, HVAC, and lighting draw about 80 kW. But during the Friday dinner rush, the kitchen runs every piece of equipment simultaneously, the dining room lights are at full brightness, and the HVAC is fighting the heat from the kitchen — your load spikes to 180 kW for about 45 minutes.

Your billed demand for the entire month is 180 kW, even though you only hit that level for a brief period. If your demand rate is $12/kW, that spike alone adds $2,160 to your bill — roughly the same as running at 80 kW for the entire month would cost in demand charges ($960).

This is why demand charges feel disproportionate. A single peak event — even one lasting just 15 minutes — sets your demand charge for the entire billing cycle.

Why Do Demand Charges Exist?

Demand charges are not arbitrary. They reflect a real cost that the grid incurs to serve your business. The electrical infrastructure — transformers, substations, distribution lines — must be sized to handle your peak load, not your average load. If your business can draw 200 kW at peak, the grid must have the capacity to deliver 200 kW at a moment's notice, even if you typically only use 80 kW.

Building and maintaining that infrastructure costs money regardless of whether you use it every day or once a month. Demand charges are how the TDU recovers the cost of reserving that capacity for your business. The higher your peak, the more infrastructure is needed, and the more you pay.

This is also why demand charges are typically assessed by the TDU (as delivery charges) rather than by your REP. Some REPs also include their own demand component in the energy supply portion of your bill, but the largest demand charges come from the delivery side.

Which Businesses Are Most Affected?

Demand charges hit hardest when there is a big gap between your average usage and your peak usage. Industries with "peaky" load profiles pay proportionally more in demand charges:

• Restaurants — Kitchen equipment creates massive spikes during meal rushes. A restaurant might average 60 kW but peak at 150+ kW during dinner service.
• Manufacturing facilities — Starting heavy machinery creates brief but intense demand spikes. A single large motor starting up can spike demand by 50-100 kW for just a few minutes.
• Hotels — Morning routines (simultaneous showers, breakfast cooking, HVAC ramp-up) create predictable daily peaks.
• Cold storage and warehouses — Refrigeration compressors cycling on simultaneously can spike demand significantly above the facility's average draw.
• Healthcare facilities — Medical equipment, sterilization systems, and HVAC requirements create high peak-to-average ratios.

Businesses with flat, consistent load profiles — like data centers or facilities that run 24/7 at steady output — tend to have lower demand charges relative to their total bill because their peak is not much higher than their average.

How to Reduce Your Demand Charges

Since demand charges are based on your single highest peak, the strategy is straightforward: flatten your load profile. Reduce the gap between your peak and your average. Here are practical approaches:

Stagger Equipment Startup

The most common cause of unnecessary demand spikes is turning on multiple pieces of heavy equipment simultaneously. If your business opens at 6 AM and every HVAC unit, compressor, oven, and lighting system kicks on at 6:00, you create an artificial peak that sets your demand charge for the month. Instead, stagger startups over 15-30 minutes. Start HVAC first, then lighting, then kitchen equipment. This simple change can reduce peak demand by 15-25% with zero impact on operations.

Pre-Cool or Pre-Heat Your Building

If your HVAC is your biggest load, consider running it during off-peak hours to pre-condition the space. Cooling your building gradually overnight (when demand charges are not being measured against peak pricing) reduces the HVAC load during business hours when other equipment is also running.

Monitor Your Demand in Real Time

You cannot manage what you do not measure. Many commercial meters and energy management systems can show you real-time demand. Some will even alert you when you approach a threshold, giving you time to shed non-critical loads before a new peak is set. Even basic interval data from your TDU (available through your online account) can reveal when your peaks occur and what is causing them.

Evaluate Your Load Factor

Load factor is the ratio of your average demand to your peak demand. A high load factor (close to 1.0) means you use power consistently. A low load factor means you have big peaks relative to your average. Improving your load factor — by flattening peaks and filling valleys — directly reduces the demand charge portion of your bill. Our expert guide on load factor explains how to calculate and improve this metric.

Demand Charges and Your Contract Choice

Understanding demand charges also affects which rate structure works best for your business. If demand charges are a large percentage of your bill, focusing exclusively on the per-kWh energy rate is a mistake — you could negotiate the lowest energy rate in the market and still have a massive bill because of demand.

Some REPs and commercial electricity contract structures handle demand charges differently. A few include demand in their all-in rate (effectively averaging it into the per-kWh price), while others break it out separately. When comparing contracts, always ask how demand is treated and compare total cost, not just the energy component.

For businesses with high demand charges, the most impactful savings often come from operational changes (load management, equipment scheduling) rather than from switching REPs or negotiating a lower energy rate. An energy broker can help identify which approach delivers more savings for your specific situation. A 10% reduction in peak demand through better load management can save more than a 5% reduction in your per-kWh energy rate.

The Bottom Line

Demand charges are one of the most misunderstood — and most expensive — components of a commercial electricity bill. They reward consistent usage and penalize peaks. Understanding how they work gives you a powerful lever for reducing your electricity costs that most businesses never think to pull.

Start by pulling your last three electricity bills and identifying the demand charge line items. Our guide to when to renew your contract covers how timing affects total cost. Compare your peak demand to your average usage. If there is a significant gap, you likely have room to reduce your bill through operational changes alone — before you even start shopping for a new rate.