I thought it was something special, not to lower the temperature setting
of the central heating during the night.
But a study in 2012 showed that 27% of the households in the Netherlands
do not turn the temperature of the central heating down at night.
The name of the research: "Residential Energy Literacy and Capitalization."
Since 2018 the new build houses in the Netherlands are energy efficient.
For those houses it is better to keep the temperature the same during day and night.
I raised the temperature in 2012 to 22.5°C, due to increased neck problems.