Advanced Lighting Techniques Lecture (PDF)

ID427 Advanced Lighting Techniques Lecture (8) Lighting Design - 2 (Art &workplace Lighting) Presented by: Sara Ibn Omer  2 Lighting Art  Three-dimensional objects are perceived as a result of the relationship between highligh...

ID427 Advanced Lighting Techniques Lecture (8) Lighting Design - 2 (Art &workplace Lighting) Presented by: Sara Ibn Omer  2 Lighting Art  Three-dimensional objects are perceived as a result of the relationship between highlight and shadow.  Concentrated beams create higher contrast and deeper shadows, emphasizing form and texture.  3 Con…  Lighting a vertical surface behind an object provides a luminous backdrop to separate the object visually from its background.  Lighting an object from the side as well as from above provides added dimension to the piece.  4 Con…  when an object is lighted from a less conventional angle, when the expected relationship of highlight and shadow is reversed, Perception is disturbed.  5 Paintings and Flat Works of Art  For lighting paintings and flat works of art, two principal methods exist: 1. Uniform illumination 2. Non uniform illumination.  6 Con…  uniform illumination characteristics: 1. Providing uniform lighting for all vertical surfaces that will receive art, gives prominence to the architecture. 2. No hierarchy is established among the individual works of art. 3. Allowing viewers to select their own focus. 4. Objects are flexible to be changed without readjusting the lighting equipment  7 Con…  Non uniform illumination. 1. Providing non uniform lighting focuses light on individual works while leaving the surround in comparative darkness. 2. Gives prominence to the art over the architecture, 3. Creating a more dramatic environment. 4. Every time the art changes, the lighting equipment must also be adjusted.  8 Con… 5. Point source object lights are ideal. 6. More than one luminaire is required because of the size of the work to be lighted. 7. Track systems are often selected because the track luminaires are easy to locate and aim (focus) as needed and providing a simple method of power distribution..  9 Con…  For flat works mounted on a vertical surface, the optimum location for a light source is usually at an angle of 30° from nadir (straight down) to average eye level (5 ft 3 in AFF). Optimum placement for lighting art.  10 Uniform illumination for art. Non uniform illumination for art.  11 Conservation of Materials  Conservation of materials is a fundamental concern in the lighting of art.  All organic material is susceptible to pigment change and weakening from exposure to light and its associated heat.  12 Con…  Damage is related to wavelength.  Ultraviolet (UV) radiation causes more damage, but much less UV than visible radiation is present in all light sources, including day-light.  A material that is fairly fast (more stable) but never the less susceptible to damage, such as the oil in paintings, will be changed mainly by UV radiation.  (E.g.: In the museum environment, it is necessary to limit both UV and visible radiation.) why????  13 Material protection  Three steps will help to protect materials from the potential damage caused by light and heat: 1. Evaluate daylight exposure (because it contains a much higher proportion of UV than do electric sources.), 2. Evaluate electric light exposure (evaluate the fluorescent and HID lamps. Although they emit UV radiation less strongly than daylight) 3. Evaluate duration of exposure (Exposure is the simple product of illuminance and time.(The same amount of damage will be produced by a large quantity of illuminance for a short time or a small quantity of illuminance for a long time. ) Work place lighting Workplace Lighting Lighting systems in the workplace provide for accurate perception at a specific task area (a desk, counter, machine, or workbench). This is achieved by using one of two lighting methods: 1. General-ambient approach. 2. Task-ambient approach. General Ambient Lighting Ambient lighting is provided by two basic methods: 1. Down lighting (direct):  Where overhead luminaires provide a downward light distribution. 2. Up lighting (indirect):  where pendant luminaires provide upward light that is then reflected from the ceiling.  1. Down lighting (Direct) Luminaires are arranged according to the ambient lighting requirements For direct ambient lighting, the spacing criterion (SC), or spacing-to-mounting-height (S/MH) ratio, provided by the luminaire manufacturer, gives the maximum recommended spacing between luminaires to achieve uniform, ambient lighting.  S Con… To quickly assess the potential of a downlight luminaire to provide uniform illumination of the horizontal plane, SC is the center- to-center distance between Spacing-to-mounting-height ratio. luminaires, (spacing) based on For example, if the SC = 1.5, then for an their mounting height above the 8-ft ceiling height, work plane. MH = 8 ft 0 in – 2 ft 5 in to the work plane = 5 ft 5 in AFF  S = MH × SC S = 5.5 ft × 1.5 = 8.25 ft  S Example (1)  Question:  Calculate the spacing from the center of one luminaire to the center of the next. If the maximum spacing criterion is 1.2, Answer : the room height 10 ft and the Sc= 1.2 work plane height is 0.75 m. MH = Mounting height above the work plane = 10 ft – 2.5ft (0.75m) = 7.5 ft S= MH × SC = 7.5 × 1.2= 9 ft  Con… Because of wall surface absorption, maximum distance from the last row of luminaires to the wall is usually one-half to one-third the spacing in the room to prevent a falloff in illuminance near the walls. Linear pattern, continuous 1 ft × Regular pattern, 2 ft × 2 ft 4 ft rectilinear luminaires. square luminaires. Regular pattern, 6-inch-diameter Supplementary illumination near round aperture luminaires. the wall.  Con… Office partitions block some overhead light from a direct system, preventing it from reaching work surfaces. Depending on the location of the downlights, some areas will be left in shadow. Some areas have noticeable shadows from office partitions, especially when partitions Well designed up lighting, because it are located on three sides of the work surface. produces even illuminance overhead, softens and reduces this shadowing.  2. Up lighting (Indirect) The primary use of up lighting (indirect lighting) is to create evenly luminous ceilings that reduce reflections. A well-designed indirect luminaire has a wide distribution. Multiple luminaires are located so that their light output will be evenly distributed across the ceiling without hot spots or areas of high luminance. properly located indirect luminaires with wide distributions produce even luminance. Improperly located indirect luminaires with narrow distributions produce areas of uneven luminance.