As the patterns of our lives shift in response to COVID-19, our energy profiles are shifting too. Overall, electricity demand has decreased and is expected to remain lower as commercial buildings, factories, and other large electricity users slow or stop operations. Residential use, on the other hand, is expected to rise as we shelter in place. On March 12, Bloomberg claimed, "Every day’s a weekend." But it's a weekend day when people stay inside Zooming, streaming, and gaming.
Pecan Street has been monitoring electricity use and generation from hundreds of homes in our research network for nearly a decade. Many of these homes have rooftop solar and electric vehicles (EVs), and we've been measuring each home's total energy use as well as use from individual circuits, like heating/cooling, EV charging, refrigerators, and so forth.
So we decided to take a look at how our participants' energy profile has changed since COVID-19 sent everyone home. The charts here include energy data from 113 homes in our research network. All of the homes are located in a neighborhood in Austin, Texas. 74 of the homes have rooftop solar. 50 of them have Level 2 EV chargers. We selected homes for which we have data from at least three previous Marches, so we can see how trends differ, given the range of weather patterns we experience in Texas in spring.
Here's what we found.
Total Residential Demand Is Up All Day Long
Our first snapshot was conducted on March 26 and includes data from March 1 to 25. For historic comparison, we averaged the figures from previous Marches (2017, 2018, and 2019). Daily residential demand was ~20% higher than in previous Marches.
We then examined demand over the course of the month. We had some warm spells during March (we'll address that below), but overall, demand is up visibly compared with previous Marches, and it increased throughout the month as more announcements were made and more people stayed home.
COVID-19 Is Changing the Duck Curve
One of our network's most unique qualities is its high penetration of rooftop solar. In Austin, March is one of the months that solar customers significantly recoup on their investment. Solar production is very high and energy use is fairly low, so they "sell" a lot of energy back to the grid. That's not the case this March. Though individual homes experienced brief periods of negative demand and sent power back to the grid, on average, the curve of our blended homes shifted upward with less of that energy going back to the grid. The solar homes in the analysis are using every kilowatt of electricity they produce during the day. This snapshot includes data from March 1 to 25.
When March ended, we reran the analysis and broke the month into the so-called "phases of shutdown" in Austin — March 1 to 14, when things were just starting to change, March 15 to 22, and March 23 to 31, which captures the city's official Stay Home-Work Safe order.
EV Chargers Are Getting a Rest
Not surprisingly, demand for EV charging is way down since Austinites started staying home. Demand dropped considerably once Austin ISD closed early for spring break (March 12) and Mayor Adler signed the Stay Home-Work Safe order (March 24).
Refrigerators Are Working Overtime
If you think you're spending a lot of time in front of an open refrigerator, you're probably right. Today's refrigerators are much more efficient than older models and the homes in our research network have newer-than-average models. Even so, demand is up considerably. Frequent opening and closing isn't the only possible culprit, however. Families are likely storing leftovers more than usual; putting warm leftovers in the fridge kicks the appliance into overdrive.
In addition to historical comparisons, we examined refrigerator use through Austin's "stages of shutdown." Compared with the first two weeks of the month, refrigerator demand is up considerably.
HVAC – Families Are Keeping Their Cool. Literally.
Energy demand in Austin is heavily influenced by air conditioning, and not just during our brutal summers. Even in March, temperature swings can produce significant spikes in energy use. So, comparisons with previous Marches can be difficult. That said, here's the daily demand from HVAC for the month.
We used kilowatt-hours of HVAC demand per cooling degree days (CDD) to account for weather variances. A CDD is the number of degrees that the outside temperature averages over a target temperature for a day. The more CDD, the more likely someone is to run their air conditioner. We used the fairly standard 65° for our calculations. Even after accounting for weather swings, residents are using about 40% more electricity to cool their homes.
So, residents were asking their HVACs to work more than you'd expect them to based on kilowatt-hour per CDD. They're home more and more, and are likely adjusting the thermostat. The air conditioner simply isn't getting the breaks it usually does.
Methodology and other details are given below.
- We examined a subset of our participants that have been part of our network for several years and favored homes with rooftop solar and EVs so we could capture how these technologies contributed to any changes.
- Our calculations include a total of 113 homes. 74 of them have rooftop solar. 50 of them have Level 2 EV chargers.
- In each of these homes, our sensor equipment measures demand (and for solar, generation) as frequently as every second.
- All homes are located in one neighborhood in Austin, Texas.
- For several of the comparisons, we examined the average demand throughout the day (kilowatts) and for each day of the month (kilowatt-hours). For historic comparison, we averaged the figures from previous Marches (2017, 2018, and 2019).
Details About March 2020 in Austin Texas
- All of the homes included in these analyses are part of Pecan Street's research network and are located in Austin, Texas.
- Austin experienced one of the country's first high-profile COVID-related cancellations when SXSW was called off on March 6.
- Spring break for many Central Texas school districts was March 16 to 20. Austin Independent School District canceled all classes on March 12, the last day before spring break, and has closed all school buildings and facilities until May.
- March weather in Austin is extremely varied. March 2020 included dramatic swings of cool (60s) and warm (low 90s) high temperatures the entire month. Pecan Street's analysis of HVAC demand will account for this variation.