Simply for thermostat setbacks when you are away at work -- energy
savings technique.

> Why in the heck a thermostat should know the time or daylight savings,
> if that stuppid thing works only with temperature?  When it is cold
> inside my house I want that mechanical switch to turn on the heater,
> independently of time and season.  Of course it would make sense to a
> comercial site when after some time nobody would be there anymore, just
> empty space.
>