Based on various reports from Denmark and Austria [2-7] on monitoring projects during the last years, realistic hot water demand profiles were elaborated. The evaluation of monitoring projects of in total 66 one family houses and apartments in Denmark and Austria gives us an overview of realistic hot water consumption.

For both evaluations we can see the typical distribution of the consumption over the year with a maximum in winter time and a minimum in summertime due to the changes of the cold water temperature over the year and due to the behaviour of the inhabitants. Looking on the energy consumption, it is interesting to see that the apartments in the passivhouses have about half the consumption of the consumption of the one family houses. The main reason is that water saving equipment typically is installed in passivhouses.