Lighting 4.pdf

Electrical Installation

Lecture No.11

Dr.Mohammed Tawfeeq Alzuhairi

The reflection coefficients ρ can be used to determine the utilization factor UF for any luminaire from the manufacturers catalogues when the room index is calculated. For example, Table -2 gives the utilization factor UF for a fluorescent luminaire with single 40W lamp and prismatic diffuser0011

mm length for different values of the room reflection

coefficients: C – ceiling reflection, W- wall reflection, F- floor reflection. If these values are: (0.5, 0.5, 0.2) and the room index is calculated to be 1.50, then the UF = 0.52. Table -2 Utilisation factor for fluorescent luminare with single 40W lamp and prismatic diffuser 0011 mm length. Room Reflection

Room Index

C

W

F

.75

1.00 1.25 1.50 2.00 2.50 3.00 4.00 5.00

.70

.50

.20

.44

.50

.56

.60

.65

.69

.72

.75

.77

.30

.38

.44

.50

.54

.60

.64

.68

.72

.74

.10

.33

.40

.46

.50

.56

.61

.64

.69

.72

.39

.44

.49

.52

.57

.60

.62

.65

.67

.30

.34

.40

.44

.48

.53

.56

.59

.62

.64

.10

.30

.36

.41

.44

.50

.53

.56

.60

.62

.34

.39

.42

.45

.49

.51

.53

.55

.57

.30

.30

.35

.39

.42

.46

.49

.51

.53

.55

.10

.27

.32

.36

.39

.44

.47

.49

.52

.54

.22

.26

.29

.31

.34

.36

.38

.40

.41

.50

.30

.00

.50

.50

.00

.20

.20

.00

UF Note: The reflection coefficients for a standard room are: (0.7, 0.5, 0.2)

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