On Feb. 26, San Antonio Realtor Alex Perches posted a listing on Facebook for a home at 206 Northaven St., just south of the cluster of hospitals that makes up the South Texas Medical Center on the city’s North Side.

In addition to its four bedrooms, three bathrooms, and 2,500 square feet, the home had another valuable asset: It did not lose power during the winter storm that hit Texas the week before. Perches was among a handful of real estate agents across the state posting on social media in February with the hashtags #hospitalpowergird or #firestationpowergrid.

These agents had figured out that local power grids across Texas were more vulnerable than many residents had realized. Not only that, but different parts of each grid could be shut off deliberately, while others maintained power. When forced to cut electricity demand by record amounts to keep the entire state’s grid from collapsing, utilities shut off power to an estimated 4 million Texas households.

A few observers were quick to recognize the potential of the connection between reliable power and property values. In a Facebook post, one North Texas real estate agent predicted power reliability as the “next trend in Texas real estate.”

“Across the state, we are seeing listing agents promoting properties as being near a hospital, near a fire station, and in more reliable grid locations than other properties,” Marvin Jolly, the chair of Texas Realtors, a statewide trade organization, said in a phone interview this month. “So we’re seeing that marketing all over the place.”

However, Jolly said his organization has “big concerns” with this information being used as a selling point for a property. In many cases, the underlying facts about the configuration of local electrical grids remain “unsubstantiated,” he said.

“Without reliable information on that, a buyer could buy a property that’s next door to a fire station thinking, ‘My power will never go out,’” Jolly said. “They may have medical issues. They may have some type of really, really important need to have reliable electricity. And if one of our members says the power will never go out at this house, and then the power goes out, then we have a legal issue and maybe a safety issue.”

Map details San Antonio’s shutoffs

Experts say Texas’ winter storm was by far the largest forced electrical outage in U.S. history. Multiple days of snow, ice, and subfreezing temperatures hit the entire state, crippling many of its under-insulated power plants and natural gas systems.

Calls for blackouts came from the Electric Reliability Council of Texas (ERCOT), the state’s grid operator. ERCOT dictated how much power demand needed to be cut, but local utilities were left to decide how to implement the blackouts. At one point during the storm, more than 300,000 CPS Energy customers were without power.

Since then, CPS Energy has faced questions about why some parts of the city faced blackouts and others didn’t.

After the storm, San Antonio Mayor Ron Nirenberg convened a Committee on Emergency Preparedness made up of City Council members and volunteers. Questions about the lopsided blackouts on the grid were among those it submitted to CPS Energy.

On April 23, CPS Energy officials gave the committee the utility’s most detailed map to date showing how the storm affected San Antonio’s neighborhoods disproportionately.

Utility officials refer to the act of deliberately shutting off power to reduce electricity demand as “shedding load.” The map shows broad swaths of mostly residential areas that CPS Energy has classified as a “load shed area,” meaning an area eligible for controlled blackouts.

Northern San Antonio has a greater share of these areas than other parts of the city, the map indicates.

A map CPS Energy released on April 23 shows the areas that experienced blackouts during the Feb. 14-20 winter storm. The yellow “load shed area” shows the areas eligible for controlled blackouts — where CPS Energy intentionally shut off power to customers. Light gray areas were ineligible for blackouts during the storm. Dark gray areas labeled “government boundary” indicate military bases. Credit: Courtesy / CPS Energy

CPS Energy shuts off power at the level of a circuit, essentially a major electrical conduit that branches off from an electrical substation. Each circuit serves approximately 10,000 to 20,000 homes and businesses, according to CPS Energy officials.

People not included in the load shed area might have been spared because they live relatively close to sites deemed critical. In other words, if a residence or business maintained power during the storm, it could have been located on the same circuit as a hospital, a police or fire station, or the San Antonio International Airport.

But others avoided the blackouts despite not living close to a critical site, for a slightly more technical reason.

Utilities must keep some circuits electrified simply to maintain the proper frequency of the grid. CPS Energy officials describe these circuits as a “separate and distinct group of circuits that shed automatically without human intervention to protect the grid when significant frequency deviations occur.”

CPS Energy has said that approximately one-third of its local service area is tied to a critical site. Another third of the system is ineligible for shut-off because of frequency maintenance, according to the utility.

That leaves the unlucky ones, the remaining one-third eligible for shutoff.

CPS Energy’s map shows major streets, but it’s difficult to tell whether a particular property lies inside or outside the load shed area. To further complicate things, people outside the load shed area might have lost power during the storm because of an equipment failure – downed power lines, blown transformers, and the like – rather than have been deliberately shut off by CPS Energy.

Even Reed Williams, the former District 8 councilman who chairs the Committee on Emergency Preparedness, said the map released in April “doesn’t tell me what I need to know.”

“I wouldn’t waste any time on it,” Williams told the San Antonio Report when asked about CPS Energy’s map.

Williams said he wants to see a “heat map” that shows what areas of town had power shut off the longest. It’s less helpful to find out whether a circuit was simply on or off during the storm, he said.

“I need to know what was the intensity, the duration,” Williams said. “I’m not there yet.”

A reluctance to share power grid data

Across the state, utility officials have been reluctant to share maps of their systems, even after public outcry following the storm. The primary concern they cite is security. What if a terrorist planted a bomb along a power circuit that serves a critical site, such as a hospital?

“We will protect that circuit-level information from that basis alone,” Chief Customer Engagement Officer Rudy Garza said during a phone interview the week of the storm. But Garza mentioned another reason as well.

CPS Energy needs the flexibility to shut off power where it sees fit in order to maintain the overall stability of the grid, Garza said. Texas grid officials have warned that without the statewide blackouts, the grid might have collapsed entirely and taken weeks to fully reenergize.

“Everybody will want to figure out how to get their circuit taken out of the rotation,” Garza said. “And the more detail we get into, that’s where the conversation will inevitably go.”

Williams thinks CPS Energy should inform its customers if they’re located on an “interruptible circuit.” People who need oxygen or dialysis machines in their homes need to know if they might have their power shut off, he said.

But more importantly, Williams said, San Antonio needs a complete overhaul of its emergency communications systems so that residents can find out in real time whether blackouts are coming and how to prepare. Williams is among those who have faulted the utility for a lack of clear communication before and during the storm.

“You need to be able to adjust your response and let people know that you’re adjusting your response during the event as it’s happening,” Williams said of CPS Energy. “You can’t just think you know what’s going to happen going in. That’s arrogant; it doesn’t work.”

Right now, information on local grid reliability is incomplete, at least for those outside the utility. And the interest sparked during the storm is waning, at least according to real estate professionals.

Market memory is short

Perches, the San Antonio Realtor who posted about the #hospitalpowergrid, said the interest in the power grid from San Antonio homebuyers dropped off quickly following the storm. Three months later, with home prices rising and San Antonio in the midst of a hot spring home sale season, the issue of reliable power stopped coming up, he said.

“That’s not on the front mind anymore,” Perches said, adding that buyers are instead just “trying to get their offer accepted, no matter where it is.”

Rolling blackouts are rare events. Before February, it had been a decade since Texas faced such extreme power grid failures.

James Gaines, a Texas A&M University real estate economist, has studied the housing market’s response to flooding in Texas, including from Hurricane Harvey, which pummeled Houston and its suburbs in 2017.

Gaines and his colleagues have found that property owners and buyers quickly lose their wariness to hold real estate that may have flooded only a few years earlier.

“Our general analysis is that the market memory is about two years,” Gaines said.

Missy Stagers, who’s worked as a Realtor in San Antonio for 26 years, said some out-of-state buyers who had seen news reports about the Texas winter storm crisis had asked her about power grid stability. But she’s never gotten the question from any local homebuyers.

“What I am seeing is local people that may have a concern medically,” Stagers said. “They are asking more questions about generators, whole-house generators. That is on an uptick.”

Still, Stagers, who wasn’t aware of CPS Energy’s map until a reporter told her about it, said she wants to know more.

“I can’t say it’s the topic of conversation anymore, but it was definitely a topic of conversation during it and shortly after [the storm],” Stagers said. “And I do think people are extremely curious about it.”

Brendan Gibbons is a former senior reporter at the San Antonio Report. He is an environmental journalist for Oil & Gas Watch.