Xcel smart thermostat users lose their cool after power company locks them out

They were asking for it, energy giant says

Thousands of Xcel Energy customers in Colorado this week discovered they’d been locked out of their smart thermostats, unable to adjust their air conditioning systems as local temperatures rose about well above 90°F this week.

At a time when cyberattacks are a daily occurrence, customers would have been forgiven for thinking their smart thermostat had been compromised by some miscreant. In reality, the culprit was none other than the power company.

On Tuesday, Xcel confirmed 22,190 customers — roughly 1.5 percent of the energy provider’s 1.5 million Colorado customers — received a message that their thermostat would be temporarily locked due to a “loss of generation.”

In an email to The Register, Xcel noted that all customers affected by the lock out had signed up for its Colorado AC Rewards program. The voluntary program allows Xcel to take control of customers' smart thermostats during “the hottest summer days,” to “ease the strain on the electrical grid” in exchange for a $100 bill credit when they sign up and a $25-per-year credit thereafter.

According Xcel, adjustments to customers' thermostats may occur anytime during aircon-heavy seasons, but customers typically “have the ability to opt out of control events any time.” However, on rare occasions “system emergencies may cause a control event that cannot be overridden.” Xcel contends this was the case Tuesday when it experienced a power supply disruption.

While Xcel says customers are made aware of these conditions when signing up, the lock out likely came as a surprise to many. The company said events like these are extremely rare, and "this is the first time it’s occurred in the program’s six-year history.”

According to Xcel, the program isn’t limited to Colorado. The energy provider says it has more than 45,600 customers enrolled in such programs across four states: Wisconsin, Minnesota, South Dakota, and Colorado.

No so smart after all

This isn't the first time an energy company has taken over customers' thermostats to reduce the load on its infrastructure. Last summer several Houston, Texas, residents complained their thermostats had been mysteriously overridden.

CBS affiliate KHOU Channel 11 reported at the time that many customers returned to find their homes approaching 80°F. It was later determined that their smart thermostats had been enrolled in an energy saving program called “Smart Savers Texas,” which works with local energy providers to adjust customer’s thermostats during energy shortages.

But unlike Xcel’s AC Rewards, which provides cash incentives for participation, the Texas customers are instead entered into a sweepstake.

A recent paper from Cornell University suggests programs like these may not be all bad, despite getting some hot under the collar. The paper published earlier this summer found that as smart thermostats grow more popular, they’re putting a strain on US power grids.

The problem essentially boils down to default schedules that mean thermostats come online simultaneously throughout the day. This, the academics explain, creates a spike in demand that puts a strain on the grid.

The US is hardly the only country where citizens are contending with weather-related power disruptions. Authorities in China last month announced mandatory power cuts in response to an unprecedented heatwave, which has left many citizens relying on candlelight and block of ice to keep cool. Those cuts have since extended to many manufacturing plants in the region. ®