Rule 21-18-16. Not everyone knows about it, but it allows you to save on heating

The 21-18-16 principle for heating suggests optimal temperatures for different rooms to save energy and improve health. Living areas should be kept at 21°C, bedrooms at 18°C, and less-used spaces at 16°C. Bathrooms require higher temperatures of 22-24°C to prevent mold growth. Maintaining these temperatures can lead to lower heating bills and better sleep quality, while temperatures below 15°C can cause issues with heating efficiency and increased energy costs.