Lighining presentation 5

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Lighining presentation 5

  1. 1. EH 342 Building construction IVSources of light Lighting or illumination is the deliberate application of light to achieve some practical or aesthetic effect. Lighting includes the use of both artificial light sources such as lamps and light fixtures, as well as natural illumination by capturing daylight. Daylighting (using windows, skylights, or light shelves) is often used as the main source of light during daytime in buildings. This can save energy compared with artificial lighting, which represents a major component of energy consumption in buildings. Without proper design, energy can be wasted by using too much lighting, or using out-dated technology. Proper lighting can enhance task performance, improve the appearance of an area, and have positive psychological effects on occupants.
  2. 2. EH 342 Building construction IVSources of light One of the core tenets of proper lighting is uniform illumination, which is required in many applications such as projection displays, LCD backlights, medical lighting, microscopy, solid-state lighting, and general lighting. Indoor lighting is usually accomplished using light fixtures, and is a key part of interior design. Lighting can also be an intrinsic component of landscape projects.
  3. 3. EH 342 Building construction IVSources of lightLighting Fixtures Lighting fixtures come in a wide variety of styles for various functions important functions are as a holder for the light source, to provide directed light and to avoid visual glare.  Some are very plain and functional, while some are pieces of art in themselves. Nearly any material can be used, so long as it can tolerate the excess heat and is in keeping with safety codes. An important property of light fixtures is the luminous efficacy or wall-plug efficiency, meaning the amount of usable light emanating from the fixture per used energy, usually measured in lumen per watt..
  4. 4. EH 342 Building construction IVSources of light A fixture using replaceable light sources can also have its efficiencyquoted as the percentage of light passed from the "bulb" to thesurroundings.The more transparent the lighting fixture is, the higher efficacy.Shading the light will normally decrease efficacy but increase thedirectionality and the visual comfort probability.Color temperature for white light sources also affects their use forcertain applications.
  5. 5. EH 342 Building construction IVSources of lightLighting fixtures come in a wide variety of styles for variousfunctions.The most important functions are as a holder for the light source, toprovide directed light and to avoid visual glare. Some are very plain and functional, while some are pieces of art inthemselves.Nearly any material can be used, so long as it can tolerate theexcess heat and is in keeping with safety codes.An important property of light fixtures is the luminous efficacy orwall-plug efficiency, meaning the amount of usable light emanatingfrom the fixture per used energy, usually measured in lumen per watt.
  6. 6. EH 342 Building construction IVSources of light Lighting is classified by intended use as general, accent, or task lighting, depending largely on the distribution of the light produced by the fixture. Task lighting is mainly functional and is usually the most concentrated, for purposes such as reading or inspection of materials.  For example, reading poor-quality reproductions may require task lighting levels up to 1500 lux (150 footcandles), and some inspection tasks or surgical procedures require even higher levels. Accent lighting is mainly decorative, intended to highlight pictures, plants, or other elements of interior design or landscaping. General lighting (sometimes referred to as ambient light) fills in between the two and is intended for general illumination of an area.
  7. 7. EH 342 Building construction IVSources of lightForms of lighting include alcove lighting, which like most otheruplighting is indirect.This is often done with fluorescent lighting (first available at the1939 Worlds Fair) or rope light, or occasionally with neon lighting. Itis a form of backlighting.Soffit or close to wall lighting can be general or a decorative wall-wash, sometimes used to bring out texture (like stucco or plaster) ona wall, though this may also show its defects as well. The effect depends heavily on the exact type of lighting sourceused.Recessed lighting (often called "pot lights" in Canada, "can lights" orhigh hats" in the US) is popular, with fixtures mounted into theceiling structure so as to appear flush with it.These downlights can use narrow beam spotlights, or wider-anglefloodlights, both of which are bulbs having their own reflectors.
  8. 8. EH 342 Building construction IVSources of lightThese downlights can use narrow beam spotlights, or wider-anglefloodlights, both of which are bulbs having their own reflectors. Thereare also downlights with internal reflectors designed to acceptcommon A lamps (light bulbs) which are generally less costly thanreflector lamps. Downlights can be incandescent, fluorescent, HID(high intensity discharge) or LED.Track lighting, invented by Lightolier, was popular at one pointbecause it was much easier to install than recessed lighting, andindividual fixtures are decorative and can be easily aimed at a wall. It has regained some popularity recently in low-voltagetracks, which often look nothing like their predecessors because theydo not have the safety issues that line-voltage systems have, and aretherefore less bulky and more ornamental in themselves.
  9. 9. EH 342 Building construction IVSources of lightA master transformer feeds all of the fixtures on the track or rodwith 12 or 24 volts, instead of each light fixture having its own line-to-low voltage transformer. There are traditional spots and floods, aswell as other small hanging fixtures. A modified version of this iscable lighting, where lights are hung from or clipped to bare metalcables under tension.A sconce is a wall-mounted fixture, particularly one that shines upand sometimes down as well. A torchiere is an uplight intended forambient lighting. It is typically a floor lamp but may be wall-mountedlike a sconce.The portable or table lamp is probably the most commonfixture, found in many homes and offices.The standard lamp and shade that sits on a table is generallighting, while the desk lamp is considered task lighting. Magnifierlamps are also task lighting.
  10. 10. EH 342 Building construction IVSources of light The illuminated ceiling was once popular in the 1960s and 1970s but fell out of favor after the 1980s. This uses diffuser panels hung like a suspended ceiling below fluorescent lights, and is considered general lighting. Other forms include neon, which is not usually intended to illuminate anything else, but to actually be an artwork in itself. This would probably fall under accent lighting, though in a dark nightclub it could be considered general lighting. In a movie theater each step in the aisles is usually marked with a row of small lights, for convenience and safety when the film has started, hence the other lights are off.  Traditionally made up of small low wattage, low voltage lamps in a track or translucent tube, these are rapidly being replaced with LED based versions.
  11. 11. EH 342 Building construction IVRoof lights and dormers A dormer is a structural element of a building that protrudes from the plane of a sloping roof surface.  Often conflated with the term "dormer", a dormer window is a window set into the dormer. Like skylights dormer windows are a source of light and ventilation for top floors, but unlike skylights (which are flush with the roof surface) they also increase the amount of headroom in the room and allow for more usable space. Examples: Gable fronted dormer,Hipped roof dormer, Flat roof dormer
  12. 12. EH 342 Building construction IVRoof lights and dormers
  13. 13. EH 342 Building construction IVLuminanceLuminance is a photometric measure of the luminous intensity perunit area of light travelling in a given direction.It describes the amount of light that passes through or is emittedfrom a particular area, and falls within a given solid angle.The SI unit for luminance is candela per square metre The CGS unit of luminance is the stilb, which is equal to one candelaper square centimetre or 10 kcd/m2.
  14. 14. EH 342 Building construction IVLuminanceLuminance is often used to characterize emission or reflection fromflat, diffuse surfaces.The luminance indicates how much luminous power will be detectedby an eye looking at the surface from a particular angle of view.Luminance is thus an indicator of how bright the surface will appear.In this case, the solid angle of interest is the solid angle subtended bythe eyes pupil. Luminance is used in the video industry to characterize thebrightness of displays. A typical computer display emits between 50 and 300 cd/m2. The sunhas luminance of about 1.6×109 cd/m2 at noon.reference^ "Luminance". Lighting Design Glossary.http://www.schorsch.com/kbase/glossary/luminance.html. RetrievedApr. 13, 2009
  15. 15. EH 342 Building construction IVLight fixturesLighting fixtures come in a wide variety of styles for variousfunctions.The most important functions are as a holder for the light source, to provide directed light and to avoid visual glare. Some are veryplain and functional, while some are pieces of art in themselves.Nearly any material can be used, so long as it can tolerate the excessheat and is in keeping with safety codes.An important property of light fixtures is the luminous efficacy orwall-plug efficiency, meaning the amount of usable light emanatingfrom the fixture per used energy, usually measured in lumen perwatt.A fixture using replaceable light sources can also have its efficiencyquoted as the percentage of light passed from the "bulb" to thesurroundings.
  16. 16. EH 342 Building construction IVLight fittingsThe more transparent the lighting fixture is, the higher efficacy.Shading the light will normally decrease efficacy but increase thedirectionality and the visual comfort probability.Color temperature for white light sources also affects their use forcertain applications.for white light sources also affects their use for certain applications.The color temperature of a white light source is the temperature inKelvin of a theoretical black body emitter that most closely matchesthe spectral characteristics of the lamp. An incandescent bulb has a color temperature around 2800 to 3000Kelvin; daylight is around 6400 Kelvin.
  17. 17. EH 342 Building construction IVLight fittings Lower color temperature lamps have relatively more energy in the yellow and red part of the visible spectrum, while high color temperatures correspond to lamps with more of a blue-white appearance.  For critical inspection or color matching tasks, or for retail displays of food and clothing, the color temperature of the lamps will be selected for the best overall lighting effect Lighting is classified by intended use as general, accent, or task lighting, depending largely on the distribution of the light produced by the fixture. Task lighting is mainly functional and is usually the most concentrated, for purposes such as reading or inspection of materials. For example, reading poor-quality reproductions may require task lighting levels up to 1500 lux (150 footcandles), and some inspection tasks or surgical procedures require even higher levels.
  18. 18. EH 342 Building construction IVLight fittings For example, reading poor-quality reproductions may require task lighting levels up to 1500 lux (150 footcandles), and some inspection tasks or surgical procedures require even higher levels. Accent lighting is mainly decorative, intended to highlight pictures, plants, or other elements of interior design or landscaping. General lighting (sometimes referred to as ambient light) fills in between the two and is intended for general illumination of an area. Indoors, this would be a basic lamp on a table or floor, or a fixture on the ceiling. Outdoors, general lighting for a parking lot may be as low as 10- 20 lux (1-2 footcandles) since pedestrians and motorists already used to the dark will need little light for crossing the area
  19. 19. EH 342 Building construction IVLight fittings Methods Downlighting is most common, with fixtures on or recessed in the ceiling casting light downward. This tends to be the most used method, used in both offices and homes. Although it is easy to design it has dramatic problems with glare and excess energy consumption due to large number of fittings. lighting is often used to bounce indirect light off the ceiling and back down. It is commonly used in lighting applications that require minimal glare and uniform general illuminance levels.  Uplighting (indirect) uses a diffuse surface to reflect light in a space and can minimize disabling glare on computer displays and other dark glossy surfaces.
  20. 20. EH 342 Building construction IVLight fittingsIt gives a more uniform presentation of the light output in operation. However indirect lighting is completely reliant upon the reflectancevalue of the surface.While indirect lighting can create a diffused and shadow free lighteffect it can be regarded as an uneconomical lighting principle.Front lighting is also quite common, but tends to make the subjectlook flat as its casts almost no visible shadows.Lighting from the side is the less common, as it tends to produceglare near eye level.
  21. 21. EH 342 Building construction IVLight fittingsForms of lighting include alcove lighting, which like most otheruplighting is indirect. This is often done with fluorescent lighting(first available at the 1939 Worlds Fair) or rope light, or occasionallywith neon lighting. It is a form of backlighting.Soffit or close to wall lighting can be general or a decorative wall-wash, sometimes used to bring out texture (like stucco or plaster) ona wall, though this may also show its defects as well.The effect depends heavily on the exact type of lighting sourceused.Recessed lighting (often called "pot lights" in Canada, "can lights"or high hats" in the US) is popular, with fixtures mounted into theceiling structure so as to appear flush with it.These downlights can use narrow beam spotlights, or wider-anglefloodlights, both of which are bulbs having their own reflectors. There are also downlights with internal reflectors designed toaccept common A lamps (light bulbs) which are generally less costlythan reflector lamps.
  22. 22. EH 342 Building construction IVLight fittings There are also downlights with internal reflectors designed to accept common A lamps (light bulbs) which are generally less costly than reflector lamps. Downlights can be incandescent, fluorescent, HID (high intensity discharge) or LED. Track lighting, invented by Lightolier, was popular at one point because it was much easier to install than recessed lighting, and individual fixtures are decorative and can be easily aimed at a wall. It has regained some popularity recently in low-voltage tracks, which often look nothing like their predecessors because they do not have the safety issues that line-voltage systems have, and are therefore less bulky and more ornamental in themselves.  A master transformer feeds all of the fixtures on the track or rod with 12 or 24 volts, instead of each light fixture having its own line- to-low voltage transformer. There are traditional spots and floods, as well as other small hanging fixtures. A modified version of this is cable lighting, where lights are hung from or clipped to bare metal cables under tension.
  23. 23. EH 342 Building construction IVTask Lighting The convention is simply to measure the intensity of illumination on a work plane Taken to be a horizontal surface situated 0.85m above floor level This intensity of illumination is known as illuminance and is measured in lux The more detail the work been done the higher the level of illumination on the working plane 
  24. 24. EH 342 Building construction IVTask Lighting Recommended illuminances in electrically lit rooms vary from 150 lux for storage areas to 3000 lux for work surfaces like picking of small items like diamond eg: Domestic living- 50 lux Offices labs - 500 lux Out door - 5000 lux In order for a room to be well lit other consideration should be given: relative brightness of surfaces Modelling characteristics of illumination Glare control Colour rendering Relative brightness 
  25. 25. EH 342 Building construction IVTask Lighting Relative brightness Adequate lighting should fall not only on the work plan, but ceiling, walls A lighting system that will direct light both horizontally as well as vertically Sensible colour on the floor, wall and ceiling Light coloured surfaces make it easier to achieve good light The appropriate measure of adequate lighting is scalar illuminance This is the average illuminance over the whole surface of tiny sphere at a particular point in space due to light arriving from all directions eg: if the scalar illuminance of 150 lux is not less than half the horizontal illumanance of 300 lux then it can assumed that all surfaces of the room will appear adequately lit This measurement takes into account the following: 1. the proportions of the room height, length and width combined into a single figure called the room index(measured with a nomogram) a
  26. 26. EH 342 Building construction IVTask Lighting Relative brightness Adequate lighting should fall not only on the work plan, but ceiling, walls A lighting system that will direct light both horizontally as well as vertically Sensible colour on the floor, wall and ceiling Light coloured room surfaces will aid to achieve good scalar illumination in most rooms The appropriate measure of adequate lighting is scalar illuminance This is the average illuminance over the whole surface of tiny sphere at a particular point in space due to light arriving from all directions 
  27. 27. EH 342 Building construction IVTask Lighting Relative brightness This is the average illuminance over the whole surface of tiny sphere at a particular point in space due to light arriving from all directions eg: if the scalar illuminance of 150 lux is not less than half the horizontal illumanance of 300 lux then it can assumed that all surfaces of the room will appear adequately lit Scalar measurement planar measurement Horizontal illumination measured in lux equals lumen per m2 of horinzontal surfaces. Scalar illumination is lumens per m2 of spherical surfaces
  28. 28. EH 342 Building construction IVTask Lighting Relative brightness This measurement takes into account the following: 1. the proportions of the room height, length and width combined into a single figure called the room index(measured with a nomogram) 2. the reflectances of the major surfaces of the room, floor, wall and ceiling 3. the pattern of the downward light spread achieved by the electric light fitting (BZ) A low BZ number means that downward light distribution tends to be concentrated A high BZ number means that downward light distribution tends to be dispersed The higher the BZ no. The more light will tend to fall on the walls
  29. 29. EH 342 Building construction IVTask Lighting Modelling characteristic of illumination If there is absolutly uniform distribution of light in all direction the modelling power of the illumination may be adequate There should be sufficient contrast btn. highlights and shadows to give the best results without being harsh Illumination vector – if the point of highest illumination and the opposite point of lowest illumination are identified on that tiny notional sphere then both the direction of the light flow will be known and the illumination difference btn. The two opposite poles measured in lux.
  30. 30.  An illumination vector has both direction and magnitute (and magnitude being measured in lux) An illumination vector under a downlighter will be virtually vertical this is usually unpleasant for most people. Single overhead light fitting in the middle of the room gives good modelling if it emits light side ways as well down. There should be sufficient contrast btn. highlights and shadows to give the best results without being harsh Illumination vector – if the point of highest illumination and the opposite point of lowest illumination are identified on that tiny notional sphere then both the direction of the light flow will be known and the illumination difference btn the two opposite poles measured in lux. Taken together the two characteristics will give us the illumination vector of the lighting in a room. The result will be that one can calculate a vector comprising both magnitude and direction.
  31. 31. Illumination vector continued Room finishes and lighting systems affect the vector magnitude i.e. dark coloured floors reflect little light upwards, therefore the notional sphere will have a darker underside than the brighter upper sphere. Therefore making lighting in that room unpleasant. However lighter floors reflect light upwards and therefore the notional sphere will not have a darker underside, but rather there will be sufficient upward light flow to give a pleasant soft modelling.
  32. 32. Vector/Scalar ratio This is the ratio between the magnitude of the illumination vector and the scalar illumination. The ratio can be used to estimate the working measure of the modelling effect of lighting. A ratio higher than 1.8 is unpleasant, that lower than 1.2 will be indistinct and excessively soft. An ideal ratio would be about 1.5.
  33. 33. Tips Low BZ number and •Rooms need to have a fraction ratio provide dominant direction of lighting rather than completely good modelling rooms diffused light with light coloured • A good and comfortable lighting is that of 15 to 45 floors. degrees to horizontal plane. Therefore side windows in conjunction with overhead lighting give good results. A high BZ number with a low fraction provides better modelling with dark coloured floors.
  34. 34. Glare control Tips When a room is •Risk of glare is increased with long rooms. brighter than average •Low ceilings in large rooms it causes visual •Dark decorations discomfort. This is •The lack of diffusers known as “Glare” •Electric fittings with high BZ value tend to increase glare.
  35. 35. Colour rendering  Incandescent light fittings give a natural look whereas florescent lights give objects a unnatural look. Task lighting  When the work environment is close to a window then the required intensity of illumination on the work plane is described in terms of daylight factor.  Daylight factor is the ratio of the luminance of the horizontal plane inside the building compared to that outside the building at the same instant.Amenity lighting
  36. 36. Amenity light Moderately sized side windows will add much to the amenity of a room by throwing light on wall surfaces If the side windows are too large problem of glare and heat control are likely Roof lights may provide very good task lighting, a pronounced vertical light direction is found unpleasant Incandescent light fittings give a natural look whereas florescent lights give objects a unnatural look.Task lighting When the work environment is close to a window then the required intensity of illumination on the work plane is described in terms of daylight factor. Daylight factor is the ratio of the luminance of the horizontal plane inside the building compared to that outside the building at the same instant.

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