Real Numbers for Lafayette Summers
A thermostat question deserves a real answer, not a shrug. For most homes across Lafayette, Broussard, Youngsville, and the rest of Acadiana, the cooling season sweet spot is 75-78°F when someone is home and awake, 80-82°F when the house is empty for a normal workday, and a range close to your daytime setting overnight for sleep comfort. These numbers aren't a guess — they reflect what a properly sized residential AC system can hold efficiently against South Louisiana's heat and humidity without running itself ragged. The table below breaks it down by scenario, and every section after it explains the reasoning so the numbers actually make sense in your own house.
Thermostat Settings by Scenario
Use this as your baseline, then adjust a degree or two once you know how well your specific house holds temperature and humidity.
| Scenario | Recommended Range | Why |
|---|---|---|
| Home & awake | 75-78°F | Comfortable for most people once humidity is controlled. Every degree below 75°F adds meaningfully to runtime without adding much felt comfort. |
| Away (workday, errands) | 80-82°F | High enough to cut runtime while the house is empty, low enough that the system isn't fighting a badly overheated, over-humid house when it kicks back on. |
| Asleep | 74-77°F | A degree or two cooler than daytime supports sleep, but staying close to the daytime number avoids a long, hard recovery cycle overnight. |
Humidity Is Half the Comfort Equation
Temperature only tells half the story in Louisiana. A house at 76°F and 50% relative humidity feels comfortable. A house at 76°F and 65% relative humidity feels muggy and warm, which is exactly why so many Lafayette homeowners end up cranking the thermostat down to "feel" cool when moisture, not heat, is the actual problem.
Aim for 45-55% relative humidity indoors during cooling season. Above roughly 60% RH, most people feel sticky and warm no matter what the thermostat says. Below 40% RH is rare in an Acadiana summer and usually isn't something you need to worry about.
A properly running AC system pulls humidity out of the air as a byproduct of cooling, but only if it runs long enough in each cycle to do it well. That's one reason the fan setting matters: leaving it on Auto rather than On lets moisture drain away from the coil, while running the fan continuously recirculates that moisture back into the airstream before it can leave the house. If the house still feels humid with the thermostat set correctly and the fan on Auto, that usually points to an airflow, ductwork, or sizing issue rather than a settings problem — see House Feels Humid for the common causes.
Does a Big Setback Actually Save Money Here?
The National Rule of Thumb
The advice you'll find most places is simple: set the thermostat back 7-10 degrees while you're away and save on your energy bill. That advice comes from drier climates, and in Lafayette it needs an asterisk.
Why Louisiana Humidity Changes the Math
Turning the thermostat up aggressively — say, from 77°F to 85°F or higher — while the house is empty does cut runtime during that window, and it will lower your bill somewhat. But Louisiana humidity doesn't take the afternoon off just because the AC does less work. While the house sits warm and mostly idle, humidity climbs right along with the temperature, and it soaks into furniture, drywall, and carpet along the way. When you get home and drop the setting back down, the system has to fight both problems at once: pulling the temperature down and pulling a much larger load of moisture back out of the air and everything that absorbed it. That recovery period runs long and hard, and it eats into a real chunk of the savings the setback was supposed to create.
The Better Balance for Acadiana
A moderate setback — roughly 3-5 degrees above your daytime setting, landing in that 80-82°F range — is usually the better call for this climate. It still meaningfully cuts runtime while you're gone, but it doesn't let the house get humid enough to force a two-front recovery when you walk back in. If you're away for several days rather than a single afternoon, a somewhat larger setback makes sense, but the system should still be allowed to run periodically rather than sitting off completely — a house sealed up and un-cooled for days in Acadiana summer heat can develop a humidity problem that takes a while to fully resolve.
Short cycling is when the system turns on and off in quick bursts instead of running a full, steady cycle. It's most often caused by an oversized system, a dirty filter, or a thermostat set to swing too far too fast — and it's a problem because a short cycle rarely runs long enough to strip much humidity out of the air, even though it satisfies the temperature setting. If your system seems to start and stop constantly, that's worth a look regardless of what the thermostat is set to. See AC Repair if that sounds like your system.
Homeowners dealing with an unusually high electric bill despite reasonable settings should also rule out equipment and airflow issues before assuming the thermostat schedule is to blame — see High Electric Bill for the most common causes.
Where a Smart Thermostat Actually Helps
What Scheduling and Geofencing Automate
Programmable and smart thermostats — the Nest, Ecobee, and similar models are the most recognizable examples — earn their keep by automating exactly this kind of moderate setback instead of relying on someone remembering to adjust it by hand. A schedule that steps the temperature up a few degrees on a predictable morning departure and back down before you're normally home removes the guesswork and the temptation to overcorrect. Geofencing, which uses a phone's location to start adjusting the temperature before you actually walk in, is particularly well suited to Acadiana's setback math: it gives the system a head start on recovery instead of waiting for someone to change the setting at the door.
What a Smart Thermostat Can't Fix
Nest, Ecobee, and similar smart thermostats are mentioned here as common examples of the category, not as specific products confirmed for your system — ask about compatibility with your equipment before buying one.
A smart schedule can't rescue a system that's already undersized, leaking air through bad ductwork, or losing capacity from a maintenance issue. Point a setback schedule at a struggling system and it will still miss its recovery window. Variable-speed equipment tends to handle setbacks and recovery more smoothly than single-stage systems, since it can ramp up gradually instead of simply switching on at full blast — worth asking about if setback swings are a recurring frustration. See Variable Speed HVAC for more on how that equipment behaves differently.
Common Mistakes That Undo Good Settings
- Cranking the thermostat down to cool the house "faster." Setting it to 65°F when you actually want 75°F doesn't cool the house any faster — the system runs at the same capacity no matter what the setpoint is. All that accomplishes is overshooting the temperature you wanted, and it can contribute to short cycling if the system satisfies the setpoint before it's had time to fully strip humidity from the air.
- Turning the system off completely while away. In Louisiana humidity, a fully off system lets moisture climb unchecked for hours, which usually means a longer, harder recovery than a moderate setback would have required.
- Running the fan on "On" instead of "Auto." Continuous fan operation recirculates moisture off the coil back into the house instead of letting it drain away, working directly against your humidity control.
- Blocking or closing vents in unused rooms. It's a common instinct to save energy, but it changes system pressure and airflow in ways that can reduce efficiency and stress the equipment rather than saving money.
- Ignoring a thermostat that reads inaccurately or responds slowly. Good settings on a bad thermostat still produce bad results. See Thermostat Not Working if yours seems unresponsive or the reading doesn't match how the house actually feels.
Maintenance That Makes Any Setting Work Better
Thermostat settings only work as well as the system carrying them out. A few basics keep any setting range performing the way it should through a full Acadiana cooling season:
- Check the air filter monthly during peak season and replace it as soon as it looks restricted — a clogged filter cuts airflow across the coil and undermines both temperature and humidity control.
- Keep supply and return vents open and unblocked by furniture, rugs, or curtains throughout the house.
- Keep the area around the outdoor unit clear of grass clippings, leaves, and overgrown plants so it can reject heat properly.
- Have the system professionally serviced on a regular schedule so refrigerant charge, airflow, and drainage are confirmed rather than assumed.
- Address problems like short cycling, weak airflow, or a system that runs constantly without catching up promptly, rather than trying to compensate for them with thermostat settings alone.
When the Thermostat Isn't the Real Problem
If you're following these ranges and the house still doesn't feel right — too warm, too sticky, or the bill keeps climbing regardless of the setting — the number on the wall usually isn't the actual issue. It's more likely airflow, ductwork, insulation, or equipment performance underneath it. NILOV serves Lafayette, Broussard, Youngsville, Carencro, Scott, Duson, and Milton, and can walk through your specific system to figure out whether it's a settings issue or something the thermostat alone can't fix. See our Lafayette service area page for coverage details, or reach out through our contact page with what your system is doing.