Environmental Engineering Reference
In-Depth Information
1.7 Energy Efficiency Indicators
Even now, the guidelines and design standards do not provide restricted
utilisation strategies for conditioned air in building spaces. Indeed, this situ-
ation creates several inefficient systems and results in an expensive energy
invoice. In some critical facilities, such as hospitals, HVAC designers face
the problem of balancing the attainment of comfortable conditions with effi-
cient energy utilisation. The relationship between HVAC system designs
and optimum conditions and energy utilisation is still under investigation
even today. Recent research [55,56] has investigated the effect of ventilation
design on comfort and energy utilisation. The effect of the displacement ven-
tilation on the humidity gradient in a factory located in a hot and humid
region has been illustrated [55], showing the strong dependence between the
correct supplying conditions and comfort. Indeed, displacement ventilation
is recommended as an energy-efficient system; the resulting humidity and
temperature gradient gives the designers the suitable tolerance for selecting
more economical Air supply conditions [55]. In recent years, new ventilation
system designs, such as under-floor systems, are becoming more popular for
overcoming the problems of current systems. In office buildings, under-floor
air supply is recommended as an alternative to ceiling air supply for over-
coming the lack of flexibility in the ceiling systems and for improving the
comfort conditions [55-59]. Actually, the energy utilisation mainly depends
on the optimum utilisation of the conditioned air in the conditioned spaces.
Currently, popular HVAC residential window and split units were further
investigated in terms of energy costs and energy efficiency ratios (see Tables
1.3 through 1.8; where $1 = 7.05 LE).
As the world becomes increasingly dependent on electrical appliances and
equipment, energy consumption rapidly rises every year. Many programmes
have been established in various countries to increase end-use equipment
energy efficiency. One of the most cost-effective and proven methods for
increasing energy efficiency of electrical appliances and equipment is to
establish energy efficiency standards and labels as defined in the following
section.
TABLE 1.3
HVAC Unit Characteristics (Window Units)
Cooling Capacity, kW
Power Consumption, W
EER
COP
2.64
1023
8.8
2.58
3.66
1429
8.75
2.56
5.28
2000
9.0
2.64
7.03
2697
8.9
2.61
Note:
EER = energy efficiency ratio; COP = coefficient of performance.
