Natural lighting

natural lighting

1. Subject: BUILDING SERVICES (3360604). Topic: “NATURAL LIGHTING” Guided by: Hardik K Bharpoda Government Polytechnic, Dahod

2. Sr. no. Name Enrollment no. 1 Labana Pritesh N. 156300306529 2 Bhavesh Hathila 156300306047

3. Topic: Natural Lighting

4. What is Natural Lighting / da y lightin g ? Day lighting is the controlled admission of natural light, direct sunlight, and diffused-skylight into a building to reduce electric lighting and saving energy. The components of a day lighting system are designed to bring natural light into a building in such a way that electric lights can be dimmed or turned off for a portion of the day, while preventing occupant discomfort or other building loads from increasing.

5. An Integrated Natural lighting System consists of- Daylight-optimized building footprint Climate-responsive window-to-wall area ratio High-performance glazing Day lighting-optimized fenestration design Skylights (passive or active) Daylight redirection devices Solar shading devices Daylight-optimized interior design (such as furniture design, space planning, and room surface finishes).

6. Sources of Natural Lighting

7. Benefits of Natural Lighting Occupant Satisfaction Occupant Comfort Occupant Health-Circadian rhythm Time orientation Colour rendition Colour Temperature Reduced electrical load Reduced internal heat gain

8. Sun angles Natural light enters the building through angles of the sun

9. Sun path, Altitude and Azimuth angles These are needed to know the sunshine hours on any wall

10. Daylight factor Daylight Factor is the ratio of the internal light level to the external light level  DF=(Ei/Eo) x 100% E i = illuminance due to daylight at a point on the indoors working plane E o = simultaneous outdoor illuminance on a horizontal plane from an unobstructed hemisphere of overcast sky Ei=SC+ERC+IRC

11. Sky components (SC) A sky component is the percentage of that part of daylight illumination at a point in the interior on a given plane whiach is receive directly from the sky as compored to the simultaneous exterior illumination on a horizontal plane from the entire hemisphere of an unobstructed clear sky. Skycomponent for a window of any size is computed as per NBC – 2005 Part -8 Section – 1 Annexure A.

12. External Reflected Components The ratio of that part of the day light illuminance at a point on a given plan which is received by direct reflection from external surfaces as compared on a horizontal plane from the entire hemisphere of an unobstructed clear design sky. The value of the sky component corresponding to the portion of the window obstructed by the external obstruction is computed .

13. Internal reflected component the ratio of that part of daylight alliminance at a point in a given plane which is receive by direct reflection or inter reflection from the internal surface as compared to the simulation exterior luminance on horizontal plan due to entire hemisphere of an unobstructed clear design sky.

14. Principles of Effective Natural Lighting 1. Orientation of the Building 2. Form of the Building 3.Glazing Ratio and specifications 4. Window Height and location 5. Overhead day lighting 6. Daylight Redirection

15. 1. Orientation of th e Building

16. 2. Form of the Building Shadows in a courtyard

17. 3.Glazing Ratio and specifications Glazing ratio= Area of glazing/area of external wall (25%-50%) The more the glazing ratio the more day lighting but more the solar heat gain Optimum glazing ratio depends upon the user requirement, building orientation, location, View of sky Triple glazing, tinted or reflective glass can reduce day lighting but increase thermal comfort. WWR <60%

18. As a general rule, the higher the window head height, the deeper into the space the daylight can penetrate. Therefore, good daylighting fenestration practice dictates that the window should ideally be composed of two discrete components: a daylight window and a view window. National Building code says- In office buildings, windows of 1.2m opening with sill height 1m-1.2m above floor and in residences, windows of 1- 1.1m and sill height to be 0.9-0.7m above floor. 4. Window Height and location

19. 5. Overhead day lighting Skylights can be either passive or active, the majority of skylights are passive because they have a clear or diffusing medium (usually acrylic) that simply allows daylight to penetrate an opening in the roof. They are often comprised of a double layer of material, for increased insulation. They can be of any shapes.

20. 6. Daylight Redirection  Daylight redirection devices take incoming direct beam sunlight and redirect it, generally onto the ceiling of a space. These devices serve two functions: glare control, where direct sun is redirected away from the eyes of occupants, and daylight penetration, where sunlight is distributed deeper into a space that would not be allowed otherwise. Daylight redirection devices generally take one of two forms: a large horizontal element, or louvered systems. Horizontal daylight redirection devices are often called light shelves.

21. Tubular daylight devices  Tubular daylight devices are another type of toplighting device. These devices employ a highly reflective film on the interior of a tube to channel light from a lens at the roof, to a lens at the ceiling plane. Tubular daylight devices tend to be much smaller than a typical skylight, yet still deliver sufficient daylight for the purpose of dimming the electric lighting.

22. Glare Glare, or excessive brightness contrast within the field of view, is an aspect of lighting that can cause discomfort to occupants. The human eye can function quite well if extreme levels of brightness are present in the same field of view. According to National Building Code of India, Light Control Media, such as translucent glass panes should be provided in the upper portion of openings, to reflect part of the light on to the roof, increasing the diffuse lighting within the room, preventing Glare discomfort to the occupants.

23. Thank you