Is 25 hot or cold AC?

[DiLane]

Setting your air conditioner to 25°C (77°F) is a cooling setting, but it lands within the comfortable-to-slightly-warm range for most people in a typical residential setting. For cooling, it is slightly above the optimal energy-saving recommendation of 24-26°C. In heating mode, 25°C would be considered excessively warm and inefficient. The perceived comfort at this temperature heavily depends on humidity levels, personal preference, clothing, and air circulation within the room.

Understanding the context of the thermostat setting is essential. An air conditioner cools the indoor air relative to the outdoor temperature. When set to 25°C for cooling, the system will run until the room temperature reaches that point. During a scorching 35°C day, 25°C indoors will feel refreshingly cool. However, on a mild 28°C day, the same 25°C setting might feel barely cool to some occupants. This relativity often causes confusion.

Humidity is a critical, often overlooked factor. Air conditioners dehumidify as they cool. High humidity makes a room feel muggy and warmer than the actual temperature. At 25°C and high humidity, you may still feel uncomfortably warm, prompting you to lower the thermostat. Conversely, at 25°C with low humidity and good airflow from the AC fan, the environment will feel significantly cooler and more pleasant. This explains why the same temperature can feel different in various climates or rooms.

Adherence to established energy efficiency guidelines is a key benchmark. Leading authorities like the Heating, Refrigeration and Air Conditioning Institute (HRAI) and government bodies such as Natural Resources Canada recommend setting your thermostat to 24-26°C during summer for an optimal balance of comfort and energy savings. Every degree you raise the setting above the outdoor temperature in cooling mode can save an estimated 3-5% on cooling costs. Therefore, while 25°C is acceptable, 26°C is often promoted as the more efficient standard for occupied hours.

A clearer perspective comes from comparing common temperature settings and their typical effects:

Temperature Setting (°C)	Mode	Perceived Sensation	Energy Efficiency Note
22-24°C	Cooling	Clearly cool, may feel chilly for some	Higher energy consumption
25-26°C	Cooling	Comfortable to slightly warm for most	Optimal efficiency range
27°C+	Cooling	Warm, minimal cooling effect	Maximum savings, comfort may suffer
20-22°C	Heating	Comfortable warmth	Standard heating efficiency range
25°C	Heating	Overly warm, likely stuffy	Poor efficiency, high costs

For heating mode, the recommended range is typically 18-21°C. Setting the heat to 25°C is rarely advised, as it forces the system to work much harder for a warmth level most find excessive, leading to dry air, high utility bills, and unnecessary wear on the equipment.

Ultimately, the best setting is personal and situational. Start with the industry-recommended 24-26°C for cooling. If you feel warm, first check if humidity is high or if vents are blocked. Using ceiling fans can allow you to raise the thermostat by about 1°C without sacrificing comfort, as the moving air creates a wind-chill effect. During sleeping hours, a slightly cooler setting around 22-24°C is often preferred by adults, as body temperature drops naturally.

[GriffinRose]

As a homeowner in Arizona, I’ve learned that 25°C on the AC is a warm-weather standby. During our brutal summers when it’s 43°C outside, 25°C inside feels fantastic. But in spring or fall, I definitely notch it down to 23°C or 24°C to feel any real cooling. My rule is simple: if the outdoor temp is under 32°C, I set it at 24°C. If it’s a real heatwave, 25°C or even 26°C does the job and keeps my electricity bill from spiking. The key is using the ceiling fan—it makes 25°C feel perfectly cool.

[LaXavier]

Honestly, if my roommate sets the AC to 25°C, I’m grabbing a sweater. Where I’m from, that’s not a cooling temperature; it’s what you set when you don’t want to run the AC at all. It feels like the system is barely on, just circulating slightly less-warm air. I start feeling comfortable when it’s at 23°C. I think it comes down to what you’re used to and how your building retains heat. Our apartment faces the sun all afternoon, so the thermostat might read 25°C, but the room feels like 28°C. For me, 25°C is the definition of a lukewarm, inefficient setting.

[MacSerenity]

In my work as an energy advisor, I explain it this way: 25°C is a moderate cooling set point. It’s within the recommended band for efficiency. The goal isn’t to achieve a specific “cold” feeling, but to maintain a stable, reasonable temperature differential with the outdoors. A 10°C difference (e.g., 35°C outside to 25°C inside) is a significant, effective cooling load. If clients complain it feels warm, we investigate insulation, air duct leaks, or refrigerant levels before advising a lower set point. Often, the system performance, not the number, is the issue.

[VanBrandon]

We keep our central AC at 25°C during the day when the family is home. With kids running around, it’s comfortable. We tried 24°C, and my wife was always cold. At 25°C, we’re all content, and our monthly energy use is about 30% lower compared to when we used to crank it to 22°C. At night, we program it to drop to 23°C for better sleep. It’s a compromise that works. For us, 25°C isn’t “cold,” but it’s the sweet spot where no one complains, and the bills stay manageable. It’s our default for modern, balanced comfort.