Studies on office temperature consistently point to the same range, roughly twenty one to twenty three degrees Celsius. Outside that range, attention and error rates measurably get worse.
A room that's too warm pulls your body's attention toward cooling down, which leaves less for actual thinking. A room that's too cold does the same thing in reverse, your body focuses on warming up instead.
If you work from home, keeping the thermostat steady makes a small but measurable difference. Even if you can't control the temperature, pairing the room with a cooler-feeling sound texture gives a similar sense of mental freshness.