Energy Demand of Buildings - Low Energy Cooling for Sustainable Buildings - page 10

100 kWh m − 2 a − 1 , and even to a few kilowatt hour per square metre and year in a
passive building.

1.2.2 Electricity Consumption
Total Electricity Consumption

Both heat and electricity consumption depend strongly on the building's use. In terms
of the specific costs, electricity almost always dominates. A survey carried out in public
buildings of the German state of Baden-W urttemberg found an average electricity
consumption of 54 kWh m − 2 a − 1 , in the UK values between 48 and 85 kWh m − 2 a − 1
were measured (see Figure 1.9).
When comparing the energy costs of commercial buildings with the remaining
current monthly operating costs, the relevance of a cost-saving energy concept is
apparent: more than half of the running costs are accounted for by energy and technical
services. A large part of the energy costs is due to ventilation and air-conditioning.
Electricity consumption dominates total energy consumption where the building
shell is energy optimized and can be reduced by 50% at most. Even in an optimized
passive energy office building in southern Germany, electricity consumption remained
at about 35 kWh m − 2 a − 1 , mainly due to the consumption by office equipment such as
computers (see Figure 1.10).
While the measured values for heat consumption correspond well with the planned
values, the measured total electricity consumption exceeds the planned value of
23.5 kWh m − 2 a − 1 by 42%. A survey of good practice office buildings in the UK
showed that electricity consumption in naturally ventilated offices is 36 kWh m − 2 a − 1
for a cellular office type, rising to 61 kWh m − 2 a − 1 for an open-plan office and up to

Figure 1.9 Final energy consumption by building type in Baden-Wurttemberg