Texas’ energy grid, which failed spectacularly over the winter during a stretch of historically cold weather, will be put to the test again this weekend, as temperatures across much of the state are forecast to be in the upper 90s. Despite assurances from Gov. Greg Abbott that “everything that needed to be done was done to fix the power grid in Texas,” earlier this week the Electric Reliability Council of Texas (ERCOT) urged customers to adjust thermostats to 78 degrees or higher and cut back on electricity use for several days.

Texas residents with smart thermostats are eligible for a number of programs, sweepstakes, and discounts which effectively allow energy providers to adjust their thermostats remotely during periods of high energy demand. Known as demand-response programs, some Texans were taken by surprise this week, as their thermostats were turned up without any action from them.

But that’s the way these seasonal programs, typically offered via utility companies across the country, are intended to work. Nest owners can also opt-in to programs directly via Google, Nest’s parent company, even if their local utility isn’t participating in such a program. Raising or lowering thermostats by a few degrees, can, in theory, reduce the strain on the energy grid and prevent the need for rolling blackouts.

According to a Google spokesperson, what’s happened in Texas “is related to energy programs managed by local utilities that are working as intended. These programs are not exclusive to Nest Thermostats, and users must opt in to these programs through their utility provider. Users can also opt out any time.” The spokesperson added that if an enrolled customer wants to manually adjust the temperature during a so-called Rush Hour Rewards event, they should be able to.

A spokesperson for Resideo, which makes Honeywell Home smart thermostats, also said customers enrolled in an energy savings program that allows for their thermostats to be adjusted remotely can override the change using the thermostat or the corresponding app.

We reached out to electric companies in Texas to try to get more details on what was happening. A spokesperson for TXU Energy in Dallas said the company “did not activate our demand response program this week.”

Alejandra Diaz of CenterPoint Energy, which is based in Houston and has more than 2 million residential customers (according to its website) wrote in a response to The Verge that on June 16th the company “conducted a test curtailment event from 2 p.m. to 5 p.m.,” and that such tests occur twice a year. The utility issued a notification to a company called EnergyHub, “to initiate energy curtailment for their residential customers who have agreed to participate in the program.”

Then, according to CenterPoint, “EnergyHub adjusted the thermostat setpoint” for enrolled customers and the test concluded by 5PM local time. According to AccuWeather, the high temperature in Houston on June 16th was 90 degrees.

Many Texas electricity customers are enrolled in a program called “Smart Savers Texas,” which is overseen by EnergyHub, which operates the demand response program on behalf of Texas utility companies. The terms of the program, according to EnergyHub’s FAQ:

By participating in the Program, you agree to allow EnergyHub, Inc. and your thermostat provider to remotely access your thermostat to make brief, limited adjustments to your thermostat temperature setting at times of peak electricity demand in the summer. You may benefit by seeing a reduced electricity bill. You can opt out of these temperature adjustments at any time

It’s likely that many people enrolled in this program were not aware of these terms; it’s well-established that many people don’t read the fine print on such agreements. And according to news station KHOU, some customers enrolled in the Smart Savers program in exchange for a sweepstakes entry, which makes it seem even less likely that people knew their thermostats could be adjusted remotely. Some companies offer discounts or rebates on smart thermostat purchases, or discounts on their electric bills; but the conditions aren’t always clear, and sometimes involve a lengthy list of terms.

The thermostat companies claim that their devices can be adjusted manually even after they’ve been adjusted remotely, but reports across social media reports suggest this wasn’t the case for many customers in Texas the past few days. At the very least, making people’s homes hotter during a major heat wave event — whether it’s because of a device not functioning as intended, or an energy program that might save a few pennies— seems like a bad idea.

Update: June 20th 9:12AM ET: Added more detail about energy savings programs and comments from company spokespersons

Correction: An earlier version of this article stated that Honeywell makes smart thermostats. The manufacturer is Resideo, which uses the Honeywell Home brand. We regret the error.