Comparison between modelled and measured hot water profiles

To estimate the validity of the model developed to generate DHW (Domestic Hot Water) profiles from time-use data the modelled profile for an average household member living in an apartment was compared to measured data. Figure 1 shows the hourly distribution for a weekday and a weekend day when averaged over six analysed measured months. The total hot water demand according to the model is 6.4 kWh per average person and day on a weekday and 7.3 kWh per person and day on a weekend day. The measurements, on the other hand, show an average use of 7.9 kWh for a weekday and 8.7 kWh for a weekend day.

In Figure 2 the modelled profiles are compared to measurements for one single month, in this case January 2006. Compared to the average measured profile the typical pattern is more clearly distinguished, especially in the morning, when investigating individual months. That is due to the peaks levelling out when averaged, since the peaks in power demand appears at different time different months of the year. See further in Section 3.3.


Figure 1. Comparison between measured and modelled hot water profiles for an average weekday in figure a)
and an average weekend day in figure b). Measured data are averages for six different months.

As seen mainly in Figure 2 the overall patterns in hot water demand between modelled curve and measured an individual month agree well, both showing clear morning peaks and smaller evening peaks. The magnitude of the peaks is also similar. The peaks however appear on somewhat different times in the morning. This may be due to that the two measured buildings are situated in an area, where most residents commute rather long distances to work, and therefore have showers earlier in the morning compared to the average person in the larger time-use study.

The modelled hot water demand for weekdays and weekend days was combined to form annual loads. The total hot water demand according to the model was 2.4 MWh per average person and year in an apartment (for a household member in a single-family house the figure was 1.6 MWh). This can be compared to the measured hot water use in the 24 apartments in Vasteras, where the average demand was 2.8 and 2.5 MWh per average household member for 2005 and 2006 respectively.

Updated: July 15, 2015 — 12:40 pm