Energy Demand of Buildings - Low Energy Cooling for Sustainable Buildings - page 3

heat insulation standards and the ventilation concept of passive houses, a low limit of
heat consumption has meanwhile been achieved, which is around 20 times lower than
today's average values. A crucial factor for the low consumption of passive buildings
was the development of new glazing and window technologies, which enable windows
to be passive solar elements and at the same time cause only low transmission heat
losses.
In new buildings with low heating requirements, other energy consumption in the
form of electricity for lighting, power and air-conditioning, as well as warm water in
residential buildings, is becoming more and more dominant. Electricity consumption
in the European Union is estimated to rise by 50% by 2020. Renewable sources of
energy can make an important contribution to the supply of electricity and heat. Cool-
ing and refrigeration account for about 15% of total electricity consumption world-
wide, and as much as 30% in highly developed countries with a warm climate such as
Hong Kong (Government Information Centre, Hong Kong, 2004). Peak electricity
loads in many countries now occur in summer rather than in winter. In South
Australia, for example, cooling and refrigeration were reported to account for 46% of
total electricity consumption on a hot summer's day.
Urban energy management systems should include demand predictions, databases
of consumption as well as strategies for operational control and optimization. Con-
sumption data is rarely available on an urban scale, which makes projections of
energy requirements difficult. Often there is no strategic energy management plan and
demand and supply are not properly matched. Surveys on energy consumption patterns
in communities are therefore often based on calculated demand, for example using
the appliances used in residential buildings and estimated hours of operation (Zia
and Devadas, 2007). A similar demand simulation approach was chosen to analyse
the energy efficiency and CO 2 reduction potential in the commercial sector in Japan
until 2050 (Yamaguchi et al ., 2007). Assuming relatively low increases in insulation
thickness (from zero in the year 2000 to 60 mm in 2050), the main efficiency gains
were expected through improvements in appliance electrical efficiency. This led to the
surprising fact that heat demand even rises, as internal loads due to equipment were
supposed to drop. A case study in the UK town of Leicester obtained energy savings of
20% by more efficient lighting in residential buildings, based on measured electricity
load curves from the energy supplier (Brownsword et al ., 2005).
The chapter aims to contribute information on how much energy is consumed in its
different forms in the building sector and which reductions are possible in best case
examples. Embedded energy in the building materials and construction process is not
included in the analysis, although several studies indicate a rather high importance of
material and resource use during building construction and maintenance: for example,
Pulselli and colleagues calculated that 49% of all energy is needed for the building
manufacturing process, 35% for maintenance and only 15% for use (Pulselli et al .,
2007).