What Temperature Should I Set My Thermostat To in a Texas Summer?

Somebody in your house wants it at 68. Somebody else read that 78 is the official rule. Both of them are working from bad information, which is probably why the argument never ends.

So what temperature should I set my thermostat to in a Texas summer? Most households land somewhere between 74 and 78 when they're home and awake, with the setting raised while asleep and raised further when the house is empty. But the exact number matters less here than people assume, because on a 105-degree afternoon your system has a physical limit that no setting can argue with. If yours is struggling to hold any reasonable setpoint, that's often a thermostat or calibration issue worth checking out.

We'll start by sorting out where that 78-degree figure came from, since the real story is more useful than the myth. Then we'll cover what your system can actually deliver when it's brutally hot outside. After that, a setting strategy that works, and the levers that make a house feel cooler without touching the number at all.

There's no single right number, and the federal program everyone quotes doesn't actually name one.

A practical starting point:

• 74 to 78 degrees when you're home and awake
• About 4 degrees higher while you're asleep
• About 7 degrees higher when the house is empty

Those setbacks are what ENERGY STAR actually recommends. The 78-degree figure came from an example chart, not a rule.

The Texas limit matters more. A typical system cools air about 20 degrees below what returns to it. On a 105-degree afternoon, a setting of 68 isn't a setting, it's a wish. The system just runs without ever getting there.

If your house won't hold a reasonable setting, that's a system question, not a thermostat question.

Thermostat not holding the setting? See our thermostat services in Southlake.

The number has an origin story, and it isn't the one people think.

It comes from a chart in a 2009 ENERGY STAR document showing how a programmable thermostat could be used: 78 degrees when home, 85 when away, 82 while asleep. It was an example of scheduling, not a recommendation about how warm your house should be. ENERGY STAR's current guidance is about setting back from whatever temperature you actually find comfortable.

In 2019 a TV report described it as a federal recommendation, the chart went viral, and the internet reacted about how you'd expect.

What the agency actually says. The EPA has stated plainly that ENERGY STAR does not assert that any particular temperature setting is good for households.

What the program does recommend is relative: raise the setting about 7 degrees when you're away, and about 4 degrees while you're asleep. No baseline temperature is specified.

That's a far more useful recommendation anyway. It works from whatever temperature you're actually comfortable at, rather than from a number somebody else picked.

Here's the part that settles most thermostat arguments in July.

A working air conditioner doesn't cool to a number. It removes a certain amount of heat from the air passing through it, which lands somewhere around 20 degrees cooler than the air going in. That's the machine's capability, and it doesn't change because you ask for more.

So on a 105-degree afternoon, setting the thermostat to 68 doesn't make the house colder. It makes the system run continuously, chasing a number it can't reach, with no benefit at any point along the way.

A system running without stopping on the hottest day isn't necessarily working hard for you. Often it's been asked for something it was never able to give.

Here's the useful diagnostic. If your house can't hold 78 on a hot afternoon, something is wrong, and it isn't the number on the wall. Dirty coils, low refrigerant, duct losses, and undersized equipment all show up exactly this way.

That's worth having someone look at, and a thermostat check is where it starts. It's also one of the things the annual visit is for.

Forget the chart. Here's a method.

Start from your own comfort. Find the warmest setting that's genuinely comfortable for your household, not the one you think you should be able to tolerate. That's your baseline.

Then apply the setbacks. About 4 degrees warmer while you're asleep. About 7 degrees warmer when the house is empty. Those two changes do most of the work.

Move in one-degree steps. Raise the baseline a single degree, live with it for a few days, and see whether anyone notices. Repeat until somebody does, then go back a degree.

Don't crank it down to cool faster. Your system cools at one rate no matter what the thermostat says. Setting it to 65 when you walk in doesn't speed anything up, it just overshoots and runs longer than it needed to.

Let the thermostat handle it. A programmable or smart thermostat runs those setbacks on schedule without anyone remembering to, which is the difference between a strategy and an intention.

If 76 feels fine in May and stifling in August, the number isn't what changed. These are the things that make the same setting feel different.

• Fan on AUTO, not ON. With the fan running constantly, air keeps moving across a wet coil between cooling cycles, and some of that moisture goes back into the house. AUTO lets it drain away instead.
• Humidity carries a lot of the feeling. The same temperature is comfortable or sticky depending on how much moisture is in the air, which is why a system that cools but doesn't dehumidify well never feels right.
• Ceiling fans let you sit a degree or two higher. Moving air makes skin feel cooler. They cool people rather than rooms, though, so running them in empty rooms does nothing.
• Blinds on west-facing glass. Afternoon sun through windows is a real heat load, and it arrives at the worst hour of the day.
• A clean filter. Restricted airflow shows up as a house that won't cool, which gets blamed on the thermostat more often than it deserves.

None of those change the number on the wall. All of them change how the number feels.

Sometimes it genuinely is the thermostat, and there are a few recognizable versions.

It's reading the wrong temperature. A thermostat in direct sun, above a lamp, near a kitchen, or on an exterior wall reads warmer than the room actually is. The system runs longer than it needs to, and the rest of the house ends up colder than the setting suggests.

It's failing. Thermostats do wear out. Erratic behavior, a display that comes and goes, or a system that ignores the schedule all point here.

One zone never satisfies. In a home with multiple zones, a single area that won't hold its setting is usually a zoning or ductwork question rather than a thermostat one.

A smart thermostat won't fix any of those. What it does do is make the pattern visible, since the usage history shows you how long the system actually ran and when.

Most of the time, though, the thermostat isn't the problem. It's the thing people blame because it's the part they can see.

The right setting is the warmest one your household is comfortable with, and the setbacks do the rest. When the house can't hold it, that's a system question, and we'll check the system before we blame the thermostat.

We answer calls 24/7. Before you call, read reviews from Southlake homeowners about working with Berkeys in Southlake.

Berkeys Plumbing, A/C & Electrical

Business Address: 1070 S Kimball Ave Suite 131, Southlake, TX 76092

Call (817) 481-5869 for thermostat services in Southlake.