الفهرس 
AbstractOnly 14 pages are availabe for public view
 |  | from | 452 |  |  |
| | | from | 452 | | |
Abstract
To investigate the problem of light penetration and distribu-tion in moderate sized public library reading rooms, five tests, theoretical and practical, were conducted.
The first test, using the sky projection concept, computed the percentage of the sky component received in the interior for the var-ious seasons and times of day in the North temperate zone. This was an attempt to satisfy the need for a useful tool capable of giving a quick and reasonably accurate result while the design is still in its early stages. At this stage in the design process, the intricate technicality of the illuminating engineers’ tables and formulas have proven to be of little use. This study attempts to solve this prob-
lem by simplifying the methodology.
Utilizing the data of the C. I. E. simplified table for stan-dard overcast sky, the second test measured the relative influence of the window proportion, position, and area upon the light received at the work plane.
In the third test, a model of a room was constructed to detect the surfaces influencing the amount of the internally reflected com-
ponent from windows located at one side wall. Under these conditions, the contribution of the ceiling and the rear wall were the decisive factors in the internally reflected component. This knowledge pro-vided the basis for a graphical method for determining, for lighting purposes, the optimum shape of ceiling and back wall in all types of rooms. This method proved to give more accurate, as well as more useful, data for the designer than the theory of integrated sphere
or the split-flux concept.
One of the reasons for eye strain and visual distraction is to read in an environment of unbalanced brightness grading beyond the
the adaptive tolerance of the eye. For this reason, a fourth test was undertaken to find a formula to be used in testing the efficiency of windows in providing balanced brightness in relation to the room size and the depth of the work plane. Data for this formula were obtained from recording the brightness distribution of both the natural land-scape and the sky luminance distribution.
The fifth test dealt with the influence of the window reveal shape upon the quantity and quality of light in the interior. The objective was to find a means of improving the window performance in cases where the freedom of enlarging the window is restricted. Win-dows with three different reveal shapes were chosen: reveals beveled to the exterior, square reveals, and reveals beveled to the interior.
Based on the five above tests, the following conclusions are that tall windows are more efficient in terms of light
penetration and quality than either the square window or
the horizontal window of the same glazing area,
2)that the ceiling and the back wall combined have the decisive impact upon the amount of the internally re-
flected component,)that it was possible to obtain a formula for bright-
ness grading by observation and measurement of the dis-
tribution of light in the natural landscape. For the three zones the relationship is 1:0.3:0.10. This con-
firms a previous datum presented by Hopkinson for
brightness grading, and)that the window with reveals beveled to the exterior introduces a great deal more light than when the reveals
are square or beveled toward the interior.