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Group 7: Masaa Tom Ong’olo Martha Malack Sheila Ian Omondi Brian Mathews. Lighting. HISTORY OF LIGHTING. Daylight architecture. Daylight architecture is adapting to the lighting requirements with natural light.
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Group 7: Masaa Tom Ong’olo Martha Malack Sheila Ian Omondi Brian Mathews Lighting
Daylight architecture • Daylight architecture is adapting to the lighting requirements with natural light. • The assize of rooms was also determined by the availability of natural lighting and ventilation. • Different basic types of daylighting architecture developed in conjunction with lighting conditions in the various climatic zones of the globe.
Artificial lighting • The flame which was the second light source was separated from fire, the source of warmth. • Burning branches were removed from the fire and used for the specific purpose of lighting. • All manner of chandeliers and scones were developed in a wide variety of styles. • Light began to mark man’s night-time.
Science and lighting • Francois Argand constructed a lamp that was named after him, the Argand lamp. • Use of optical instruments was also evident at this time and basic theories about light originated. • Development of photometrics by Boguer& Lambert at around the 18thC • Street lighting and stage lighting developed in areas of signaling especially in light houses.
Gas lighting • End of 18thC efficiency of gas lighting was demonstrated in a series of pilot projects. • Thermo lamps were developed and with the coupling of coke recovery and gas production, gas lighting became an economic proposition as entire sections of towns could benefit from a central gas supply. • Luminous efficacy and colour appearance in the process of thermo luminescence depended on the type of material.
Electrical light sources • Beginning of the 19thC saw the development of arch lamps that were first operated on batteries. • Mid-century self adjusting lamps were developed and later generators. • Further developments: • Glass bulb • Moore lamp • Mercury vapor lamp
Quantitative light design • 100 years later luminance levels similar to those of daylight could technically now be produced in interior living and working spaces or in exterior spaces. • Glare problems and harsh shadows. • Attempt and failure to provide comprehensive street lighting. • Task lighting. • Guidelines for lighting in general. • Provision of uniform ambient lighting.
New kind of lighting design • A new approach to designing with light related more intensely to architectural lighting and its inherent requirements was developed. • It had significance for extensively glazed facades, which were not only openings to let in daylight but also to give architecture a new appearance at night through artificial lighting. • Joachim Teichvnuller defined ‘lichtarchitektur’ as architecture that conceives light as a building material and incorporates it purposefully into the overall architectural design.
The influences of stage lighting • Stage lighting strives to create illusions. • Light alone can be applied on the same set to create the impression of different times of day, changes in weather…
Quantitative lighting design • Richard Kelly broke away from the idea of uniform illuminance as the paramount criterion of lighting design. • He substituted the issue of quantity with the issue of different qualities. • He differentiated between three basic functions: • Ambient light • Focal glow • Play of brilliance
Lighting engineering and lighting design • Differentiated lighting required specialized luminaires designed to cope with specific lighting tasks. • Industry had to meet the designers’ demands for new luminaires, and further developments in the field of lamp technology and luminaire design were promoted to suit particular applications required by lighting designers. • Compact light sources: • Halogen lamps • Metal halides • Fluorescent body
And its techniques Day Lighting
Introduction Since the beginning of habitable construction, daylighting has been a big factor in the designs of buildings. Daylighting is the practice of placing windows (and reflective surfaces) so that during the day natural light provides effective internal lighting.
Day Lighting reduces energy costs in the building while at the same time enhancing visual comfort. The presence of direct sunshine in the interior environment is also of great physiological benefit.
Techniques of daylightingBuilding Orientation and Geometry The orientation of the building plays a big role in the amount of daylight received in the building. A building oriented in the E-W axis will receive more daylight. The orientation of the building with regards to the site is also important. The fenestrations should be designed to face away from obstructions which will otherwise block daylight
The geometry of the buildings in terms of the walls, ceilings, floors and windows and how they relate with each other influences daylighting as well
Size and Location of Windows The larger the windows, the more daylight will be received in the illuminated room. Windows located on facades receiving more daylight will in turn have the rooms they are in with more light
Type of Window There are various types of windows that can be used on a building. Some of the most common are vertical windows, skylights and clerestories. All these types of windows bring in daylight, but of different quality in the spaces they illuminate.
Ground and wall treatment Smooth and light coloured walls will reflect daylight in the interior of the building, providing light of great quality. Up to 40% of daylight can also be reflected into the interior spaces through reflection from the ground, the percentage depending on the ground treatment.
Light shelves and light tubes Light shelves are horizontal devices on windows used to reflect daylight farther into a room. They can be completely outside or halfway in. Light tubes are tubes from the roof used to provide light to a focused area of the interior
What is artificial lighting? • This is basically any lighting that is not from sunlight. • It could also be referred to as light that is man made.
Light Sources • Light sources are instruments of producing light. Light sources are technical devices which convert usually electric energy into radiation - partly to light. • Based on the way they work, light sources are divided into two types of lamps: - 1.incandescent, and - luminescent.
Incandescent lamps • In incandescent lamps, light is produced by the radiation of a filament at high temperature. The spectrum of the light generated in this way contains radiation at every wavelength and its spectrum is monotonous. A considerable amount of heat is generated at the same time as light. Incandescent lamps used in practice are - filament incandescent lamps, - tungsten halogen lamps for mains voltage, and - low voltage tungsten halogen reflector lamps.
filament incandescent • Light in an incandescent lamp is produced by a tungsten filament heated by electric current. The red hot tungsten filament (about 2800 K) is in a bulb filled with a noble gas. The electric connection is made possible by a special base at one or both ends.
TUNGSTEN HALOGEN LAMPS FOR MAINS VOLTAGE • Their design differs from that of standard incandescent lamps in the following ways. The light source is linear, the envelope is made from quartz glass, and the tube contains halogens - hence the name. Bases are situated at both ends of the tube. Their operation is the same as that of standard incandescent lamps
low voltage tungsten halogen reflector lamps. • In these lamps, a small light source is built together with a mirror lamp, thus becoming a compact unit for further installation. They operate in essentially the same way as standard incandescent lamps.
Luminescent lamps • In luminescent lamps light is generated by excited electrons. An electric arc excites light in a so- called arc tube or on the surface of the envelope, as the case may be. The spectrum of the light generated this way is not necessarily continuous, radiation is much larger in certain narrow bands than in others, and the spectrum is not monotonous. Luminescent lamp used in practice are - fluorescent lamps, - compact fluorescent lamps, - mercury lamps,
fluorescent lamps • The light is produced predominantly by the fluorescent powder covering the inner wall of the tube. This powder transforms the UV radiation of the gas discharge into visible light.
COMPACT FLUORESCENT LAMPS • Compact fluorescent lamps are usually relatively small fluorescent light sources that are or can be built together with the auxiliaries partly or completely. They operate the same way as standard fluorescent lamps
Mercury lamps • Mercury lamps belong to the group of HID (high intensity discharge) lamps. These lamps have two envelopes. The inner quartz envelope is an arc tube. The gas discharge is started by a starting electrode. The radiation generated by the electric current through mercury vapour is only partly light, its invisible part is transformed into light by the fluorescent powder on the inside surface of the outer envelope. Mercury lamps need auxiliaries (ballast or starter-transformer) for their operation.
Gas Lighting. • Gas lighting is production of artificial light from combustion of a gaseous fuel, such as hydrogen, methane, carbon monoxide, propane, butane, acetylene, ethylene, or natural gas. Before electricity became sufficiently widespread and economical to allow for general public use, gas was the most popular means of outdoor and indoor lighting in cities and suburbs. Early gas lights had to be lit manually, but many later designs are self-igniting. • Gas lighting today is typically used for camping, where the high energy density of a hydrocarbon fuel, combined with the modular nature of canisters (a strong metal container) allows bright and long lasting light to be produced cheaply and without complex equipment. In addition, some urban historical districts retain gas street lighting, and gas lighting is used indoors or outdoors to create or preserve a nostalgic effect.
Light –quality and features • Controlling light • Light fixtures /light luminaires TOPICS OF DISCUSSION
Quality and features • Specific qualities of light create different perceptual conditions and thereby influence and control human perception. • Quality is unfluenced by-Illuminance- Light distribution- beam direction- the colour of a light installation- glare limitation
Quantity of light • Much investigation has gone into lighting conditions in the working environment to establish illuminance levels for optimum visual performance. • Def:Visual performance is the ability to perceive and identify objects or details, i.e. visual tasks with given contrast between the object viewed and the surrounding area • Visual performance generally improves when the illuminance level is increased but decreases rapidly at extremely high illuminance levels due to glare effects
Illuminance levels recommended for various tasks • Recognize facial features: 20 lux At the work place 1000-2000 lux At the operating theater up to 10000 lux
Visual perception • Visual perception is influenced by 3 factors- light-the object-the perceiving being • The pattern of luminances projected to the retina forms a basis for a complex process at the end of which is the image we actually see.This involves some aspects such as -the laws of gestalt-constancy phenomena-the information content of the object that is being perceived. • The image perceived is therefore not identical to the patters of luminances that fall on the retina but rather to the • Eg . The formation of shadows on a spatial body. The luminance pattern is not interpreted as being unevenly lit but rather as the feature of a three dimensional form
Diffuse and directed light • Diffuse light - produced by extensive areas that emit light such as luminous ceilings or reflected light from illuminated ceilings and walls.-illuminates the entire space but produces reduced shadows and reflections. • Directed light- emitted from point sources ; compact light sources.- essential for production of shadows on objects and structured surfaces and reflection on specular surfaces.
Modelling • The task of lighting design is therefore to create a suitabe ratio of diffuse light to directed light to meet the requirements of each individual situation • Where the spatial quality or the surface structure is of prime importance, lighting that emphasises shapes and forms is required. Only in situations where spatial quality and surface structure are of no importance, or if they are disturbing factors, can completely diffuse lighting be used • The shaping of our environment through light and shade is of prime importance for our perception of spatial forms and surface structures • Modelling is primarily effected using directed light • Too much shaping can conceal information if the shadows cast are so stark that parts of the object are concealed by the darkness
Brilliance • Brilliance is produced by compact, point light sources and is most effective when applied with an extremely low proportion of diffuse lightEg. The effect of a candle light in evening light • Objects that refract this light are perceived as specular, e.g. illuminated glass, polished gems or crystal chandeliers. • Brilliance is also produced when light falls on highly glossy surfaces, such as porcelain, glass, paint or varnish, polished metal or wet materials • Accentuates the spatial quality and surface structure because sparkling effects are mainly evident along edges and around the curves on shiny objects. • Sparkling effects are generally used in practice to make objects or spaces more interesting and prestigious or precious. • It is effective because it attracts our attention with the promise of Information content. If the brilliance is of no information value then it becomes disturbing glare also known as glare
Glare discomfort glare degree of which depends on the number, size, position, and luminance of the glare sources. Disability glare- visibility is reduced to zero eg. From a glossy magazine Veiling reflections- eg. Lighting fixture images on your computer screen
Def: Degree of change which occurs in the colour effects of objects through lighting with a specific light source in contrast to the lighting with a comparative reference light source eg. a thermal radiator or daylight. It is therefore a comparison of the similarity of colour effects under two types of lighting. Luminous colour and colour rendering . Different light sources have different Colour rendering indexes which is the measure of the ability of a light source to accurately render all frequencies of its color spectrum when compared to a perfect reference light of a similar type (color temperature). It is rated on a scale from 1-100. The lower the CRI rating, the less accurately colors will be reproduced
Reflectors Reflectors are designed to redirect the light emitted from a lamp in order to achieve a desired distribution of light intensity outside of the luminaire. Glossy or mirrored reflectors produce direct light, while matte finish reflectors produce scattered, or diffuse light. Transmitters Transmitting materials in luminairescan be transparent. This applies to simple front glass panels, or filters that absorb certain spectral regions but transmit others, Absorbers Primarily used for shielding Light sources for visual comfort. Typical absorbing elements on a luminaire are black multigrooved baffles, anti-dazzle cylinders, barn doors or louvres in various shapes and sizes CONTROLLING LIGHT
Def: A complete lighting unit that produces and distributes light to fulfill the design goals for the lighted space. LUMINAIRES/ LIGHT FIXTURE
Types of luminaires • Stationary luminaires, • Movable luminaires • Light structures