Table Of ContentPROJECT REPORT: DAY LIGHTING
PERFORMANCE OF THE LIGHT SHELF
BY SUJESH SjPATEL
University of NAIROBI Library
FOR USE IN THE
LIBRARY ONLY
A project report submitted in part fulfillment for the degree of Master of
Architecture of the University of Nairobi.
Dedicated to my father
ACKNOWLEDGEMENT
I would like to thank the following people, who during the course of my
project assisted me directly and indirectly.
1. Professor Jerry Magutu, University of Nairobi
2. Lecturer Musau Kimeu, University of Nairobi
3. Lecturer Yusuf Ebrahim, University of Nairobi
4. Architect Rajendrabhai P. Patel, Raj Architects
5. Mrs. Jasumati S. Patel, my dear mother.
6. Mrs. Tejal S. Patel, my dear wife.
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TABLE OF CONTENTS
Page
Title page............................ i
Declaration........................ ii
Dedication.......................... iii
Acknowledgment............. iv
Table of Contents.............. v
List of Tables........................ ix
List of Figures....................... x
Abstract...............................
Problem statement............ 2
Chapter One: Introduction
Introduction........................ 5
Chapter summary............. 7
Hypothesis........................... 8
Objectives........................... 10
Scope.................................. 11
v
Limitations.......................................................................................................... 12
Methodology..................................................................................................... 13
Chapter Two: Day lighting
Energy conservation......................................................................................... 15
Daylight and day lighting................................................................................ 19
Glare.................................................................................................................... 24
Contrast............................................................................................................... 26
Day lighting strategies...................................................................................... 29
Light shelves....................................................................................................... 30
Chapter Three: Experiments and results
Experiment One: Solar shading and thermal control
Introduction........................................................................................................ 33
Tools..................................................................................................................... 34
Sample space................................................................................................... 35
Assumptions........................................................................................................ 36
Measurements................................................................................................... 38
Results.................................................................................................................. 40
VI
Chapter Four. Summary and conclusions
Summary:
Experiment O ne................................................................................................. 93
Experiment Tw o ................................................................................................. 93
Experiment Three............................................................................................... 94
Conclusions:
Experiment O ne.
Experiment Two ..
Experiment Three
Light shelf design............................................................................................... 100
References......................................................................................................... 101
LIST OF TABLES
The critical Azimuth and Altitude angles for 0° Latitude 40
Surface treatments for the light shelf 72
The light shelf's position in relation to the ceiling 73
Daylight factor values recorded for light shelf with a highly 79
reflective surface
Daylight factor values recorded for light shelf with a 80
brilliant white surface
Daylight factor values recorded for light shelf with a grey 81
surface
Daylight factor values recorded for light shelf with a non- 82
reflective surface
Daylight factor values recorded for light shelves with 83
different reflective surface
The daylight factors recorded when the shelf was 4 meters 84
below the ceiling
The daylight factors recorded when the shelf was 3 meters 85
below the ceiling
The daylight factors recorded when the shelf was 2 meters 86
below the ceiling.
The daylight factors recorded when the shelf was 1 meter 87
below the ceiling.
Comparison of daylight factor for lighi shelves positioned 88
at .different height from the ceiling.
IX
UST OF FIGURES
Page
Figure 1: Schematic description of light shelf performance assessment 13
method.
Figure 2: Projected energy consumption in Kenya. 15
Figure 3: Projected electricity consumption in Kenya 16
Figure 4: Shows the proportions of subsequent running costs as spent on 1 7
various aspects at constant prices in 1992.
Rgure 5: The impact of glazing area on lighting and heating expenditure. 19
Figure 6: The wavelengths of electro magnetic radiation. 20
Rgure 7: Components of Daylight. 21
Rgure 8: A graphical presentation of contrast in a side lit room 27
Rgure 9: A graphical presentation of the Inverse Square Law 27
Rgure 10: This statue has a very high contrast against the window 28
Rgure 11: Image on the right shows a space without a light shelf and 32
image on the left shows a space light shelf.
Rgure 12: Light shelf designed for BC Gas Operation Center, Surrey. U.K. 32
Rgure 13: A Solar Chart for 0° Latitude 34
Rgure 14: Schematic plan (above) and section (below) of the sample 35
space.
Rgure 15: Shading angles 38
Rgure 16: Azimuth angle 39
figure 17: Altitude angle 39
x
The widest critical Azimuth angle solar radiation penetrates the 41
space.
The lowest critical Altitude angle of solar radiation that has to be 42
blocked.
Shading performance for a lighf shelf positioned on the upper 44
part of the window system
Shading performance for a light shelf positioned on the lower 45
part of the window system
Light shelf without an internal component positioned on the 46
lower part of a window
Lighf shelf without an internal component positioned on the 47
lower part of a window
Light shelf without an external component positioned on the 48
lower part of a window
Light shelf without an external component positioned on the 49
upper part of a window
Sun path simulator 51
Schematic plan of the model 52
Schematic section of the model 53
The solar chart showing the sun path 55
The daylight distribution for a North/South oriented opening. 56
The daylight distribution fora North/South oriented opening. 56
The daylight distribution fora North/South oriented opening. 56
The daylight distribution for a North/South oriented opening 57
The daylight distribution for a North/South oriented opening. 57
The daylight distribution for a North/South oriented opening. 57
XI
The daylight distribution for a North/South oriented opening. 58
The daylight distribution for an East/West oriented opening. 58
The daylight distribution for an East/West oriented opening. 58
The daylight distribution for an East/West oriented opening. 59
The daylight distribution for an East/West oriented opening. 59
The daylight distribution for an East/West oriented opening. 59
The daylight distribution for an East/West oriented opening. 60
The daylight distribution for an East/West oriented opening. 60
Sun’s movement on the Northem/Southem orientation 65
Sun's movement on the Eastern/Western orientation 65
Sun’s position at 8am and 4pm facing North/South 66
Sun's position at 10am and 2pm facing North/South 67
Sun’s position at Noon facing the North/South 68
Sunlight coming in at higher angle 69
Sunlight coming in at 45 degrees 70
Sunlight coming in at lower degrees 71
The mirror box used in the experiment to simulate the 74
overcast sky
Schematic plan of the model space 76
Schematic section of the model 76
Average daylight levels for light shelf with a highly reflective 79
surface
XJI
