Smart thermostat swarms are straining the US grid

Smart thermostats, those unassuming low-power gadgets designed to keep homes at comfortable temps, are having an impact far wider than most might have considered, according to recent data.

A paper from Cornell University brings bad news for renewable energy enthusiasts – smart thermostats are secretly taxing the grid.

Smart thermostats, which the paper said were present in around 40 percent of US homes in 2021, are programmed by default to have different night and day modes. In hundreds of thousands of homes across the US that means a sudden jump in electricity use right before residents wake up – if people aren't changing default settings, which the paper suggests is the case. 

Those hundreds and thousands of smart thermostats, typically configured to switch to day mode around 6am, "can cause load synchronization during recovery from nightly setpoint setbacks, increasing the daily peak heating electrical demand," the paper said. 

Cornell professor Max Zhang and PhD candidate Zachary Lee, the paper's authors, wrote that most studies predicting electrical demand fail to account for smart thermostats and the stress they can place on the grid.

"As we electrify the heating sector to decarbonize the grid, this so-called load synchronization will become a problem in the near future," Zhang said.

To address the problem, Zhang and Lee built a dataset from publicly available smart thermostat logs collected by EcoBee that contained anonymized temperature, set point, runtime, and home occupancy statistics.

They used the data to examine energy costs during a New York City winter, and found that load synchronization often occurs before renewable resources, like solar, have had a chance to kick in and take stress off the grid. That stress is actually aggravating peak demand by 50 percent, the paper said.

Zhang and Lee also found that energy-saving mechanisms built into smart thermostats are less effective than advertised, with most homeowners only seeing energy savings of 5-8 percent, as opposed to the 25-30 percent they're capable of. 

Thinking outside the home

The world is electrifying at an ever-quickening pace, and environmental problems have cropped up along the way. Electric cars create battery waste, as do other electronics, and removing carbon emissions from homes doesn't mean power plants have dropped coal and gas in favor of sustainable solutions. 

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Those solutions, like solar and wind, "require a considerable amount of real estate, and the right weather, and as a result they're typically located far from the cities they would serve," the Washington Post's Will Englund wrote. 

Smart thermostats increase frequency and magnitude of peak energy demand, and without more tenable ways to store energy from renewables, Lee said, they could offset greenhouse gas reductions from electrification.

Energy Fairness, a nonprofit allegedly funded by gas and oil interests, thinks that the challenges of electrification require emphasizing energy reliability above all else. Zhang and Lee's paper, while not arguing for the retention of fossil fuels to support grid reliability, does suggest that close monitoring will be key.

"Future energy system planning must consider the interaction of weather, generation capacity, and energy management tools, show a large performance gap between potential energy savings and actual energy savings," Zhang and Lee wrote.

Zhang suggests there may be an easier way to ease grid stress from smart thermostats: educate consumers on how to use them so default settings are changed. Even that may have its limits of effectiveness, though.

"In the end… we have to make smart thermostats even smarter," Zhang said. ®