Structural Design of the mCCHP-RES System - Design for Micro-Combined Cooling, Heating and Power Systems - page 187

Table 20 Coef cients for determining the daylight supply factor [ 17 ]
A maintained illuminance Em (lux) Daylight penetration a b

300 Weak 1.2425 − 0.0117

Medium 1.3097 − 0.0106

Strong

1.2904 − 0.0088

500 Weak 0.9432 − 0.0094

Medium 1.2425 − 0.0117

Strong

1.3220 − 0.0110

Table 21 F DC as a function of daylight penetration [ 17 ]
Control of arti cial lighting system

F DC
Weak Medium Strong

Manual

0.2 0.3 0.4

Automatic, daylight dependent

0.75 0.77 0.85

daylight dependency factor (F D ) is shown by equation:

￿

F D ¼ 1 ð F DS F DC C DS Þ ð 46 Þ

For each month must be determined monthly daylight supply factor, denoted
F DS , and the impact, denoted F DC .
The daylight supply factor F DS can be approximated as a function of latitude
c site , for latitudes ranging from 38 ° to 60 ° North, by the relation:

F DS ¼ a þ b c site ð 47 Þ

where a and b are shown in Table 20 .
The daylight supply factor F DS is valid for a daily operation hour period of 800 h
to 1,700 h. For longer daily day time operating periods the values should be
multiplied by a correction factor of 0.7. For longer non-daylight periods during the
operating time the following applies F DS = 0, i.e. F D =1.
F DC , describes the ef ciency of how a control system or control strategy exploits

the given saving potential, i.e. the daylight supply in the considered space,
described by (F DS . F DC ) does not consider the power consumption of the control
gear itself. Table 21 provides the correction factor of the daylight supply.
C DS is the monthly redistribution factor as a function of latitude and given values
for example 46 ° N latitude shown in Table 22 .