HISTORY TO LIGHTING CANDELA (cd) • 40,000 BC (the end of paleolithic period) • stones or shells of suitable shape were used for burning animal oil for lighting. 600 BC • INDEX OF THE ABILITY OF A LIGHT SOURCE TO PRODUCE ILLUMINATION • CANDELA AND CANDLEPOWER HAS THE SAME MAGNITUDE LUMEN (lm) torches were then used by the greeks with pottery and metal lamps. During that time, candlesticks of the hebrews were used as a support for a group of floating-wick lamps. • QUANTITATIVE UNIT FOR MEASURING FLOW OF LIGHT ENERGY (LUMINOUS FLUX) EMANATING FROM 1 ft² OF A 1 ft² SURFACE OF 1 CANDLEPOWER LIGHT OUTPUT. Mid 18th Century • • Flat wicks were introduced to the market. Aime argand, a french, introduced a circular wick with an open center and a glass lamp chimney. Whale oil was used in these lamps as it produces less smoke.S • SI UNITS – 1 LUMEN IS THE LUMINOUS FLUX FROM 1m² OF A 1m² OF 1 CANDELA ILLUMINATION – DENSITY OF THE LUMINOUS FLUX (LUMENS PER UNIT AREA 1802 • Gas lighting was used in baltimore and new york in the years 1817 and 1823. 1879 • Thomas alva edison, an american inventor developed the first practical incandescent lamp. It worked by passing electricity through a thin platinum filament in the glass vacuum bulb ---------------------------------------------------------------LIGHTING (ILLUMINATION) • deliberate use of light to achieve practical or aesthetic effects LIGHTING INCLUDES 1. LIGHT SOURCES (LAMPS, LIGHT FIXTURES) 2.NATURAL ILLUMINATION SKYLIGHTS, LIGHT SHELVES) (WINDOWS, FOOTCANDLE (FC) • DAYLIGHTING – MAIN SOURCE OF LIGHT DURING DAYTIME PROPER LIGHTING 1. Enhance task performance 2. Improve the appearance of an area 3. Positive psychological effects occupants 1 LUMEN OF LUMINOUS FLUX SPREAD UNIFORMLY OVER AN AREA OF 1ft² PRODUCES AN ILLUMINATION OF 1 FOOTCANDLE ---------------------------------------------------------------LIGHTING TERMINOLOGIES (cont.) on LIGHTS • Rays that travel in a straight line until they encounter some object ---------------------------------------------------------------LIGHTING TERMINOLOGIES Rays can be: CANDLEPOWER (CP) 1. Absorbed • Unit of luminous intensity of a light source 2. Reflected 3. Transmitted The proportion of light absorbed, reflected, or transmitted depends upon the type of material and the angle of incidence of the light rays as measured from the perpendicular to the surface. DIRECT TRANSMISSION • This occurs when light passes through clear, transparent materials. The angle at which the light leaves is the same as that at which it enters. DIFFUSE TRANSMISSION • • ABSORPTANCE • • The ratio of light absorbed by a material to the incident light falling on it. All materials absorb some light; darker objects absorb more light that lightercolored objects The transmitted light is scattered evenly in all directions, appearing equally bright from any angle of view. Materials that transmit light in a diffuse pattern are known as “translucent” materials. These materials are widely used in light fixtures to diffuse or spread the light evenly in all directions. REFLECTANCE/REFLECTION FACTOR/REFLECTANCE COEFFICIENT • • Ratio of light reflected by a surface to the incident light falling on it. Reflection of light is either specular, diffuse, or some combination of the two. SPECULAR REFLECTION • Referred to as “regular reflection” characterized by the angle of reflection being equal to the angle of incident light. DIFFUSE REFLECTION • REFRACTION The change of direction of a ray of light as it passes obliquely from one medium into another in which its velocity is different ANGLE OF INCIDENCE • The reflected light is scattered in all directions so that the reflecting surface appears equally bright from any angle of view. The angle that a straight line, as a ray of light falling on a surface, makes with a normal to the surface at the point of incidence. FOOTLAMBERT • TRANSMITTANCE/LUMINOUS TRANSMITTANCE/TRASMISSION FACTOR/ COEFFICIENT OF TRANSMISSION • • The ratio of the light transmitted through a material. Life reflection, light transmission may be either direct, diffuse, or a combination of the two A quantitative unit for measuring brightness BRIGHTNESS (LUMINANCE) • • • • Index of the intensity of light being emitted, transmitted , or reflected from a surface. Brightness – perceived light. Luminance – measured quantity. Footcandle: illumination is on a surface • Footlambert: the brightness is from the surface • GLARE • The effect of excessive brightness in the field of view, causing annoyance or discomfort and interfering with vision. It may be direct from a light source, or reflected from a shiny surface. TWO TYPES OF GLARE 1. DISABILITY GLARE – Refers to the reduction in visual function. Resulting in reduced contrast due to scattered light inside the eye. 2. DISCOMFORT GLARE – Occurs when people don’t feel comfortable with their given lighting conditions, yet don’t find their vision actually impaired. TWO CATEGORIES OF GLARE 1. DIRECT GLARE - offending brightness is in the field of view 2. REFLECTED GLARE - brightness is reflected from the work in such a manner as to reduce contrast or produce discomfort. THREE TYPES OF LIGHTING 1. GENERAL - Provides an area with overall illumination; provides fairly uniform lighting 2. TASK (LOCAL) - Increases light levels over the work and immediate surroundings. Local lighting often allows the user to adjust and control lighting and provides flexibility for each user. *Localized - general lighting uses overhead fixtures in addition to ceiling fixtures to increase lighting levels for particular tasks. 1. ACCENT - Directional lighting to emphasize a particular object or draw attention to a display item. Accent lighting is used inside and outside the home to feature locations such as an entrance or to create dramatic effects. ---------------------------------------------------------------NATURAL LIGHTING • a lighting source that closely replicates natural sunlight can be considered natural light source. DAYLIGHTING • • The most practical method of passive solar energy utilization in commercial buildings Reduces lighting energy use and cooling load as well Sunlight is a highly efficient source of illumination (produce levels of illumination 50 times as high as those recommended for artificial illumination. ---------------------------------------------------------------DIFFERENT TYPES OF LIGHTING FIXTURES & SYSTEMS TYPES OF LIGHTING DISTRIBUTION 1. DIRECT – luminaires distribute 90 to 100 percent of the emitted light in the general direction of the surface to be illuminated. The term generally refers to light emitted in a downward direction. Troffers and downlights are two types of direct lighting luminaires. 2. SEMI-DIRECT – luminaires distribute 60 to 90 percent of the emitted light downward and the balance upward. The shadows generated by semi-direct lighting are diffused and do not cause discomfort. Semi-direct lighting is employed in applications where strong light is not necessary (e.g., stairways, corridors, and storage areas). 3. GENERAL DIFFUSE / DIRECT-INDIRECT – luminaires distribute 40 to 60 percent of the emitted light downward and the balance upward, in some cases with a strong component at 90 degrees (horizontal). This type of light distribution integrates the characteristics of direct lighting and those of indirect lighting. 4. SEMI-INDIRECT – luminaires distribute 60 to 90 percent of the emitted light upward and the balance downward, similar to those of indirect lighting systems with the exception that the downward component usually creates a luminaire luminance that closely matches that of the ceiling. Semi-indirect lighting scheme is primarily used for indoor light decoration purposes 5. INDIRECT – luminaires distribute 90 to 100 percent of the emitted light upward. In a well-designed installation, the entire ceiling becomes the primary source of illumination, and shadows will be virtually eliminated. In this lighting scheme more than 90% of total luminous flux is thrown upwards to the ceiling for diffuse reflection by using inverted or bowl reflectors. Since the indirect lighting the ceiling and upper walls must reflect light to the work plane, it is essential that these surfaces have high reflectance. 2. HALOGEN LIGHT - Halogen is a type of lighting technology that is essentially an enhanced version of incandescent. Just like with incandescent light bulbs, the electrical current enters the socket and travels up to the tungsten filament, heating up the filament to incandescence. 3. FLUORESCENT LAMP - Contains mercury vapor, an electric arc is produced between the opposing electrodes generating some visible light Ballast – A device used with fluorescent and high-intensity discharge lamps to provide the necessary circuit conditions for starting and operating ---------------------------------------------------------ELECTRIC LIGHT SOURCES 1. INCANDESCENT LAMP - Employs the principle of converting electrical energy into heat at a temperature that causes the filament to be incandescent Incandescent – emitting light as a result of being heated. 4. HIGH-INTENSITY DISCHARGE (HID) LAMP - Produces high intensity light within an arc tube contained in an outer bulb. The metallic gas within the arc tube may be mercury, sodium, or a combination of other metallic vapors *Major applications include streetlights, gymnasiums, warehouses, large retail facilities, and stadiums, and plant growing rooms Filament – a wire that is made to glow by the passage of an electric current. TYPES OF HID LAMPS 1. MERCURY VAPOR - Mercury vapor lamps consist of an inner arc discharge tube constructed of quartz surrounded by an outer hard borosilicate glass envelope. - Mercury vapor lamps are widely used to light both indoor and outdoor areas such as gymnasiums, factories, department stores, banks, highways, parks, and sports fields 2. METAL HALIDE (MH) - Metal Halide lamps are similar to mercury vapor lamps but use metal halide additives inside the arc tube along with the mercury and argon. - Because of the good color rendition and high lumen output, these lamps are good for sports arenas and stadiums. Indoor uses include large auditoriums and convention halls. These lamps are sometimes used for general outdoor lighting, such as parking facilities, but a high-pressure sodium system is typically a better choice 3. HIGH PRESSURE SODIUM - The high-pressure sodium (HPS) lamp is widely used for outdoor and industrial applications. Its higher efficacy makes it a better choice than metal halide for these applications, especially when good color rendering is not a priority. - Sodium, the major element used, produces the "golden" color that is characteristic of HPS lamps 4. MISCELLANEOUS LAMPS - SHORT-ARC LAMPS OR COMPACT ARC LAMPS - Of the xenon family of lamps, produce light in a small tube and are the closest thing to a true point source of high luminance. - Used for search lights, projectors, or optical instruments 7. ELECTRODELESS LAMPS - Gaseous lamps excited by means of electromagnetic or microwave energy without the use of electrode - Often used in industrial properties such as factory buildings and street lights for roadway lighting 8. LED LIGHTS - LED stands for light emitting diode. LED lighting products produce light up to 90% more efficiently than incandescent light bulbs. - An electrical current passes through a microchip, which illuminates the tiny light sources we call LEDs and the result is visible light. ---------------------------------------------------------------- CORRELATED COLOR TEMPERATURE The color of the light that a bulb emits depends on its Correlated Color Temperature (CCT). The CCT replicates the Kelvin temperature of a metal object when it’s heated. “The higher the temperature, the cooler the color” 5. LOW PRESSURE SODIUM (LPS) LAMPS - Monochromatic lamps in the yellow region of the spectrum. The primary use of LPS lamps is for street and highway lighting as well as outdoor area and security lighting. The typical applications of LPS lighting include parking lots and garages, automobile and train tunnels, and street lighting. Indoor applications such as warehouses are practical where color is not important 6. ELECTROLUMINESCENT LAMPS - Emit light by direct excitation of phosphor from an alternating current. These lamps are used for night-lights and engineering applications such as luminous instrument panels.
