The measure consists in installing a timer (digital or analogic) which turns off the boiler when there is no demand of DHW (e.g. in residential buildings during the night there is no relevant demand of DHW).
Schedule different patterns of use
It must be kept in mind the time that it normally takes the water to be heated before scheduling
Initial investment: low. The cost starts from 5€ for the analog timers and from 40€ for the digitals ones which have possibility of remote control.