Energy Usage Dashboard
If you live in Ontario, Canada, the electricity regulator – the Ontario Energy Board – sets your electricity rates and plans . Electricity rates are based on two factors – how much electricity you use, and/or when you use it. Each electricity plan offers different options for both factors. You have three options in 2025 – tiered rates, time-of-use rates and the newest option – the Ultra-low overnight rate (ULO). The ULO rate could be cheapest if you own an electric vehicle and drive a lot. The exact EV usage amount when the ULO rate is cheapest depends on how much you drive and your charging requirements, i.e. when you need to charge your car. Most of my charging is overnight and the ULO rate offers a significantly cheaper option for this period. However, the ULO rates include periods during the evening when electricity rates are higher.
What this page does:
Use this page to estimate the cheapest electricity billing option for you. You must provide at least one week of electricity usage data in a CSV file. The calculations below use your hourly energy usage to calculate two typical days of electricity usage – a weekday and a weekend day. In my case, I own an EV and am trying to determine whether the ULO plan is the cheapest option.
⚠️ Important:
The input file is NOT the Green Button format. Please use a CSV file.
⚠️ Privacy Notice:
All calculations are carried out on your computer. No data is sent either to me or to
anyone else. This page uses CSS from UNPKG.com.
The chart uses the Chart.js library. If you do not recognise these words, don’t worry.
No data leaves your computer and you can use this script entirely offline.
I created this page using AI (MS Copilot). I verified that the calculations for the Tiered rates are correct for summer and winter. I did not verify the calculations for TOU and ULO rates but the cost estimates do appear plausible.
Instructions:
- Visit your electricity utility’s website and download your usage data as a CSV file. Make sure to download at least seven days of data. Save this somewhere on your computer.
- Below, click “Browse…” and find the energy usage CSV file on your computer.
- Click “Calculate”.
- The chart below will update and show your average energy usage for a typical weekday and for a typical weekend day. Note that both lines in the chart represent one day each.
- Select the season – either winter or summer rates.
- Select your pricing model and click “Calculate Cost”.
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I designed these calculations for Ontario’s electricity rates. The CSV file you download from your utility should start like this:
Date Hour 1 Hour 2 Hour 3 2025-09-01 0.42 0.38 0.45 2025-09-02 0.40 0.36 0.43
⚠️ Not working yet:
The sliders for hourly energy consumption do not work. The values at the moment are from
your electricity usage file. The eventual idea is that you can modify these values to see how
your electricity bill changes. For example, these should allow you to answer questions like
“What if I charged my car starting at 11 PM instead of 7 PM”. At the moment, these sliders do nothing.
Input – Your electricity usage file goes here: