There is no mandatory number for every home. The energy principle is simple: a lower indoor temperature reduces the temperature difference to outdoors and therefore heat loss.
Start with the lowest setting that remains comfortable
Adjust gradually and account for infants, older adults, illness, pets, and freeze risk during long absences.
Set back while sleeping or away when the system supports it
A schedule avoids heating an empty house to the same level. Heat pumps may need more modest setbacks so recovery does not trigger inefficient auxiliary heat.
Do not use the thermostat as an accelerator
Raising the setpoint dramatically does not make ordinary heating equipment warm the room faster; it simply keeps running toward a higher target.
Uneven rooms point to another issue
If one room is 65°F while another is 75°F at the same thermostat setting, investigate distribution, radiators, ducts, insulation, and air leakage instead of raising the whole house.
Manage humidity and ventilation too
A very damp house can feel colder and develop condensation. Do not block necessary ventilation simply to retain heat.
Choose a setpoint the household can tolerate comfortably and safely, then optimize schedules and building heat loss rather than chasing a universal number.
Sources
- U.S. Department of Energy — Home Heating Systems — Heating-system operation, efficiency, controls, and maintenance.