Source of light is sun, but inside a building light from the sun may reach in the following ways:
- A – Diffused or skylight , ( through window or opening).
- B – Externally reflected light ( by ground or other buildings) through the same windows
- C – Internally reflected light from walls , ceiling or other internal surfaces.
- D – Direct sunlight along a straight path from the sun through a window top a given point.
Daylight Factor
It is the ratio of illumination in a given building to the simultaneous outdoor illumination. It is taken as a constant expressed as a %.
Its valid only under overcast sky conditions, i.e when there is no direct sunlight.
D.F = Ei/Eo *100
D.F = sky component + externally reflected component + internally reflected component
Design Sky – It is the illumination value for a particular location evaluated from records of illuamination taken over a long period of time which is exceeded in 90% cases in daylight hours.
Warm Humid Climates
- Direct sunlight is avoided for thermal reasons. Bright sky can provide sufficient light but also causes glare.
- View of the sky is screened using planters or shading devices. A view of the sky up to 15° from the horizon is permissible.
- Daylight must be reflected from ground or blades up to ceiling which should be of a light colour.
Hot and Dry Climate:
- Internally reflected light is the best form of daylighting. The small size of openings and blue skies reduce the sky component in such areas.
- Shading devices used should be non reflective and positioned so that they are not directly visible as they can cause glare.
- High level windows should be used. Low level windows are acceptable only if they open onto a shaded and planted courtyard.
- Strong luminance contrast between a sunlit view and window can be avoided by painting adjacent walls and inside of window frames white.
DAYLIGHT FACTOR FOR VARIOUS SPACES
| TYPE OF BUILDING |
SPACE |
DAYLIGHT FACTOR (%) |
| DWELLING | KITCHEN | 2.5 |
| LIVING ROOM | 0.625 | |
| BEDROOM | 0.313 | |
| STUDY | 1.9 | |
| CIRCULATION | 0.313 | |
| SCHOOLS | CLASSROOMS | 1.9 |
| LECTURE | 1.9-2.5 | |
| LABORATORIES | 1.9-3.8 | |
| OFFICE | GENERAL | 1.9 |
| DRAWING | 3.8 | |
| ENQUIRY | 0.625-1.9 | |
| LIBRARY | STACK ROOM | 0.9-1.0 |
| READING ROOM | 1.9-3.8 | |
| COUNTER AREA | 2.5-3.8 | |
| CATALOGUE ROOM | 1.9-2.5 | |
| HOSPITALS | GENERAL WARDS | 1.25 |
| PATHOLOGICAL LABS | 2.5-3.8 |
To learn more about lighting, visit:
This presentation was created by: Ankita Gupta, Vineet Goyal, Akhilesh Maurya, Biswajit Behra
NICE WORK !!!
NICE WORK !!!