Environmental Engineering Reference
In-Depth Information
Table 1.2 Approximate values for nominal flux of light, and specific
connected power of energy-saving lighting concepts
Room type
Required illuminance level/
Specific electric power/
lux
W m 2
Side rooms
100
3-5
Restaurants
200
5-8
Offices
300
6-8
Large offices
500
10-20
Even in newly constructed eco-buildings, electrical energy consumption for light-
ing can be high, especially if the users do not effectively reduce artificial lighting.
A recently built office building at the University of Southampton was intensively
monitored within the European SARA demonstration project (construction completed
in 2005 with a 2600 m 2 surface area). A total annual lighting electricity value of
21 kWh m 2 a 1 was measured. The daily and monthly values showed that there was
no seasonal influence on lighting energy consumption (see Figure 1.11). Only on
weekends was there a reduction of lighting consumption, by a factor of 10.
Worldwide, 20% of the electricity produced is used for lighting. Studies show that
the introduction of market-available and highly efficient light-emitting diode technol-
ogy could reduce this consumption by 30% until 2015 and by 50% until the year 2025
(European Commission, 2006).
If energy-saving lighting concepts are applied, the connection power in office rooms
can be as low as 6-8 W m 2 , while standard values are still between 10 and 20 W m 2
(see Table 1.2).
1.2.3 Air Conditioning
Annual sales of electrical room air-conditioning units are about 43 million units with
the main markets in China (12 million) and the USA (11.8 million). The market pen-
etration in Europe is smaller (about 2.8 million units in 2002), but has a high growth
rate. Per thousand inhabitants, there are 0.6 installed units in Germany, 14 in Spain
and 12 in Italy. The growth of climatized building area in Europe is estimated to rise
from 3 m 2 per inhabitant (year 2000) to 6 m 2 per inhabitant (year 2020). The rising
air-conditioning sales are due to increased internal loads through electrical office ap-
pliances, but also to increased demand for comfort in summer. Summer overheating
in highly glazed buildings is often an issue in modern office buildings, even in north
European climates. This unwanted and often unforeseen summer overheating leads to
the curious fact that air-conditioned buildings in Northern Europe sometimes consume
more cooling energy than in Southern Europe where there is a more obvious archi-
tectural emphasis on summer comfort. According to an analysis of a range of office
buildings, an average of 40 kWh m 2 a 1 was obtained for southern climates, whereas
65 kWh m 2 a 1 was measured in north European building projects (Santamouris,
2005). Today in German office buildings the energy demand for air-conditioning
 
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