Measurements of household electricity and domestic hot water use in dwellings and the effect of different monitoring time resolution

The use of household electricity and domestic hot water has been measured for 72 apartments in an apartment building located in the south of Sweden. The measurements were carried out with samples every 6 s, a tenfold increase in resolution compared to available published data, during a measurement period of five days, in the winter season, including a weekend. The influence of the time resolution on the distribution of data was analysed by integrating the 6 s data to represent longer logging intervals. Extreme values, especially the high values, are shown to be reduced if the time interval is increased. The maximum household electric power was 50% higher at a 6 s resolution compared to 60 s and the corresponding difference for domestic hot water flow was 40%. Daily variations has to be considered for photovoltaic installations and solar thermal collectors, energy simulations of buildings need at least hourly data and all kind of power design in a building or its services benefits from much more resolved data.

► Extreme values disappear when the monitoring time interval is increased.
► High domestic hot water flow occurs very seldom.
► Power balance depends more on varying electricity than varying outdoor temperature.
► The monitoring time resolution determines the possible analysis.
► High time resolution also calls for high quantity resolution.