PhD Thesis - Energy Systems Research Unit - University of Strathclyde

7.1.2 Specify Demand
Half-hourly electricity demand profiles may be obtained from load research
groups, from some utilities where data is gathered for different types of building
for use in research and billing, and also from building energy simulation tools
[1]. Heat and hot water use profiles are, however, more difficult to find. Again,
these can be determined using building energy simulation tools, and some
typical profiles do exist, which are becoming more common with the increased
interest in CHP and district heating schemes [2,3].
As with electricity, the heat and hot water demand profiles are given in kW over
time, and some typical shape graphs are available for some types of building. If
this is not the case, a heat demand profile can be estimated for weekdays and
weekends by considering the occupancy hours of certain types of building and
creating a basic demand profile. This graph can then be augmented to produce
an annual heat demand profile by applying an extra heating load, proportional to
the number of degrees centigrade that ambient temperature is below a specified
minimum, using half-hourly ambient temperature data from the relevant climate
file [1]. This minimum temperature would generally be 15.5 degrees centigrade
for the UK, which is that used in degree-day analysis as the outside temperature
that gives comfortable inside conditions [4].
Daily or annual consumption figures must then be used to scale this profile,
which may be available in the form of meter readings or typical and best
practice values quoted for certain types of building [5]. If a total heat demand is
available in kWh then this can be directly applied to the profile. If the metered
or quoted value is for heating fuel use, the amount of fuel used for space heating
(seasonal) and for other uses (hot water and cooking) must first be determined.
To do this, the monthly fuel consumption is plotted against the number of
degree-days (as shown in figure 7.2) [6].
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