Best thermostat settings for hot climates: a room by room guide
Most thermostat advice online is written for cold countries, where the question is how low to set the heating at night. In the Gulf, the question is the opposite, and it matters more, because the AC runs for most of the year. Here's a practical way to set up smart thermostats in a cooling-heavy home.
Start with the setpoint: 24°C or higher
Dubai Electricity and Water Authority recommends keeping your thermostat at 24°C or higher. Its guidance is that each degree you raise the set point can save up to 5% on AC consumption.
That makes the setpoint the single biggest lever you have. Setting a room to 21°C instead of 24°C doesn't cool it faster. It just makes the AC run longer to reach a lower target.
Use setbacks when rooms are empty
The US Department of Energy says you can save as much as 10% a year on heating and cooling by turning the thermostat back 7 to 10°F, about 4 to 5.5°C, for 8 hours a day. For cooling, "back" means warmer.
In practice, in a hot climate:
- Let empty rooms drift a few degrees warmer during the day, rather than switching them off completely. Very hot rooms take a long time to pull back down.
- Start cooling bedrooms 30 to 60 minutes before bedtime, rather than all afternoon.
- Use away modes so the house eases off automatically when everyone is out.
A room by room starting point
| Room | When occupied | When empty |
|---|---|---|
| Bedrooms | 24 to 25°C overnight | 27 to 28°C during the day |
| Living room and kitchen | 24 to 25°C | 27 to 28°C when out |
| Majlis or formal living | 24°C when guests are expected | 28°C most of the time |
| Guest rooms | 24 to 25°C when in use | 28 to 29°C |
| Home office | 24 to 25°C in working hours | 27 to 28°C |
These are starting points to adjust for comfort, not rules. The principle is what matters: comfortable when occupied, warmer when not, and never colder than you actually need.
Put the thermostat in the right place
A thermostat can only control what it measures. The Department of Energy says it should be on an interior wall, away from direct sunlight, drafts, doorways, skylights and windows, and not blocked by furniture.
In Gulf homes, the common mistakes are:
- Next to a window. Sun on the thermostat makes it think the room is hotter, so the AC runs longer.
- In the supply air stream. Cold air blowing straight onto it makes it think the room is cooler than it is.
- Near the kitchen. Cooking heat throws the reading off.
With a DropAir adapter, the thermostat connects over a CAT6 cable, so your installer can put it where it reads the room properly rather than where the old controller happened to be.
Fan settings
Leave the fan on auto in most rooms, so it runs only when cooling is needed. Running the fan constantly uses electricity and can push humidity back into the room after the coil switches off. On fan coil systems, a lower fan speed with a properly modulating valve can be quieter and just as comfortable.
Let the schedule do the work
The savings only happen if the settings stick. That's the real advantage of a smart thermostat over a basic controller. It applies the schedule every day, eases off when you leave, and doesn't forget. On a home with an indoor unit in every room, giving each room its own thermostat and schedule is where the biggest gains are.
Summary
Set 24°C or higher when rooms are in use, let empty rooms drift warmer, place thermostats away from sun and supply air, and leave the fan on auto. Each degree higher can save up to 5% on AC use, according to DEWA. A smart thermostat on each indoor unit makes those settings automatic.