In today's society, it's becoming increasingly important to find methods which useenergy more efficiently. One established method is night time set-back. When usingnight time set-back the indoor temperature is lowered during the night. This result ina smaller temperature difference between indoors and outdoors, which in turnreduces heat losses. The method requiers that heat can be stored into and emittedfrom the building's frame. This thesis examines the effects of night time set-back on four different building types.The building types are: a concrete building from the 1960s, a concrete building fromthe 1960s with new windows and doors, a concrete building from the 2010s and awooden building from the 2020s. The thesis examines how the night time set-backaffect the heat demand, the heat power demand and the cost of heat. The results show that the night time set-back reduces the heat demand by 5-11 % forall building types that are examined. The daily average power reduces by 1-4 % for allbuilding types, which results in the cost of heating reduces by 3-7 %for all buildingtypes. The maximum power peak increases by 1-12 %. The set-up of the districitheating price model is critical for the economical outcomes. Since night time set-backcontributes to increased power peaks, new calculations for the economics can beneeded in the future if the price model change from daily power to maxiumum power(on hourly basis).