Energy Demand of Buildings - Low Energy Cooling for Sustainable Buildings - page 7

is used. To increase the share of renewable energy for water heating, some local or
regional governments have introduced legislation to cover typically 60% of the warm
water demand by solar thermal energy. In Catalunya in Spain, about 75% of the local
communities have so-called local ordinances to oblige building constructors to imple-
ment solar thermal energy. In Mediterranean climates, the energy need for warm water
heating is of the same order of magnitude as heating energy consumption, even for the
given building stock. An investigation for urban housing in Barcelona in Spain showed
that from a total end energy consumption of 8310 kWh a − 1 for residential housing of
90 m 2 average size, 29% or 26 kWh m − 2 a − 1 was used for warm water production and
38% for heating. Cooling energy need on the other hand is less than 10 kWh m − 2 a − 1
(Reol, 2005).
1.1.3 Electricity Consumption
The average electricity consumption of private households is around 3600 kWh per
household and year in Germany. Related to a square metre of heated residential space,
an average value of 31 kWh m − 2 a − 1 is obtained. An electricity-saving household
needs only around 2000 kWh a − 1 . Measured electricity consumption for several hun-
dred newly built houses in Ostfildern showed average annual consumption values
between 30 and 50 kWh m − 2 a − 1 (see Figure 1.5) . The highest number of buildings
was in the class between 40 and 50 kWh m − 2 a − 1 (see Figure 1.6). In a passive build-
ing project in Darmstadt (Germany), consumptions of between 1400 and 2200 kWh
per household per year were measured, which corresponds to an average value of
12 kWh m − 2 a − 1 .
Figure 1.5 Measured electricity consumption of newly built rows of houses in Ostfildern, Germany