I’m an Electricity Private Detective

For the last while I’ve felt like our monthly electricity bill has been creeping up significantly. I generally pay the bills in a rush of paperwork, so can’t claim to have been paying careful attention, but a simple check of January 2021 ($95.78) to January 2026 ($180.95) showed me that my intuition was right.

I set out to find the reason.

Fortunately, for the last 12 years I’ve been archiving my home electricity usage using a little device tucked away in a cupboard that connects to my electric meter every few minutes and grabs the current reading. I’ve archived over 750,000 readings in a database, giving me a rich source of data for analyzing trends and, perhaps, identifying the cause for the increase.

Google Gemini has proven very capable at doing this sort of data analysis. I exported a CSV file of the electric meter readings to it, and asked:

This is a CSV of my electric meter readings from 2014 until the present. The relevant columns are datestamp, which contains the date and time, and reading, which is the reading on the electric meter. The readings need to be divided by 100 to get the value in kWh.

I’d like the following:

1. A chart and/or analysis showing when during the day we’re using electricity.
2. A chart showing the trend of daily usage over this period.
3. Any helpful conclusions about whether the gradual increase in consumption from 2014 to present is related to time of day.

It returned some very helpful analysis, including:

Your consumption remained remarkably consistent for the first seven years of this dataset.

2014–2021: You averaged approximately 13–16 kWh per day.

The 2023–2024 Surge: Starting in late 2023, your daily consumption began to climb rapidly. By 2024, your average daily usage reached 28.9 kWh, essentially doubling your historic baseline.

Recent Stability: 2025 and early 2026 show that this higher usage has become the “new normal,” maintaining an average of 23–28 kWh per day.

And:

Comparing the hourly profiles of 2015 vs. 2024/2025 yields a clear answer: The increase in consumption is occurring across all hours of the day, but the impact is most extreme during the evening and overnight.

Evening Intensification: In 2015, your evening peak (8:00 PM) was roughly 0.9 kWh per hour. In 2024/2025, that same peak jumped to nearly 2.0 kWh per hour. This suggests that whatever was added to the home (e.g., a heat pump, EV charging, or new appliances) is being used most heavily during the evening.

Rising Baseload: Your overnight usage (3:00 AM) was historically near-zero (approx. 0.4 kWh/hour). It has now roughly doubled to 0.8–0.9 kWh/hour. This indicates a “phantom load” or an appliance that runs 24/7 (like a heat pump in “maintain” mode or a new large refrigerator/server).

Conclusion: The increase isn’t just a shift in when you use power—it is a massive increase in volume across the board, with the evening peak now being much sharper and more expensive than it was a decade ago.

I followed up:

Is there any date that you can point to where the usage obviously goes up?

The reply to that question included a chart showing the daily usage increase very clearly:

And another chart focusing on the period from mid-August to mid-October:

Its commentary:

The “Smoking Gun”: September 5–10, 2023

While your usage had small fluctuations over the years, there is a dramatic and permanent “step up” that begins the first week of September 2023.

Before Sept 5, 2023: Your daily usage was consistently in the 12–18 kWh range.

After Sept 5, 2023: Your usage immediately spiked into the 35–45 kWh range and has never returned to its old baseline.

…

Since this shift happened in early September (during a period where roof heating wires wouldn’t be in use), and the consumption remained high through the winter and into the following summer, this points to a permanent addition to the household infrastructure.

I went spelunking through my photo archive to see if there was anything that might jog my memory about that time, and, sure enough, I found this receipt from Canadian Tire for a duhumidifier:

A look through my email from the same period confirms that I did, indeed, install the dehumidifier in our (very humid) basement the first week of September 2023.

A followup conversation with Gemini suggested that leaving this unit on 24/7 from that point on could consume as much as 11 kWh per day, which explains a significant chunk of the increase.

At the current cost of 17.3 cents/kWh, the dehumidifier costs us about $60 per month to run.

There are a few other smoking guns—heating wires on the back roof that don’t have a temperature-dependent controller, summertime air conditioning, a fan we run every night to bring fresh air into our bedroom—but it looks like the dehumidifier is the likely cause of the big jump.