The forecast calls for peak demand

On Wednesday, Efficiency Vermont and Green Mountain Power declared the hot and hazy day a “peak day.”

What is peak demand?

Summer is the time of year that we tend to see the highest levels of electricity use. When we all use a little extra energy to cool off on a hot day, it adds up quickly. Demand increases dramatically, causing the cost utilities pay for electricity to increase in kind. It results in a trend known as “summer peak.

What does this mean for customers?

The cost of electricity increases. The added strain on the grid affects what energy sources we use for electricity and how much utilities pay for it. When we experience an extended heat wave, with temperatures hovering around 95 degrees, the extra demand that is put on the grid increases our energy costs anywhere between 2% and 5%.

7-23 forecasted demand

The type of generation sources that feed the grid change. During peak demand, the use of energy sources like coal and oil increases. During normal times, the fuel mix feeding the grid is largely a mix of nuclear and natural gas, with smaller percentages of renewables in as well. But when we hit peak demand, there’s a shift in the fuel mix. About half of the mix comes from natural gas, and we see an increase in oil and coal and a decrease in renewables. The two images below were taken from the ISO New England app on Wednesday. They show the energy fuel mix for low demand, and then how that mix changes when we experience a high demand scenario.

low demand fuel mix  high demand fuel mix

How can we keep cool when things heat up?

The key to reducing summer peaks is to be a smart energy consumer. Pay attention to how much energy you use, how you use it, and the time of day. Then, make adjustments accordingly. Doing so allows you to directly play a role in offsetting the high demand during peak days. Here are some simple things we did on Wednesday during peak demand:

  • Turn off overhead lights and use natural light instead

  • Power off all monitors, tv’s, equipment that do not need to be in use

  • Adjust the air conditioning to a more moderate temperature.

  • Wait to run appliances, like the dishwasher, until demand is lower

Luckily for us, we have some great partners in the state dedicated to helping us all make energy improvements in our homes and businesses. Thanks to a pilot program, Efficiency Vermont is working with 35,000 residential utility customers to reduce their energy consumption during summer peak season.  This program notifies customers when demand is projected to be particularly high, and provides free tips on what to do about it. Following each event, these customers receive feedback on how much power they were able to save, how it compares to neighbors, and what they can do next time. Even if you aren’t one of the customers in this pilot program, it’s important to know that you can play a role and that small changes taken together will have a big impact.

To learn more about this pilot program and how to make smarter energy choices visit and


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