What temperature warrants the central heating being put on?

The temperature at which central heating should be turned on can vary by personal preference, but a common guideline is around 18-21°C (64-70°F) for comfort. Many people find that if indoor temperatures drop below 18°C (64°F), it may feel too cold, prompting the need for heating. Additionally, factors such as humidity and individual comfort levels can influence the decision to turn on the heating.