Common Definitions and Terminologies in lighting design
Terminology of solar geometry
Altitude – The angular distance of any point in the celestial sphere, measured from the horizon, on a large circle passing through the body and zenith.
Azimuth is the angle measured between the meridians passing through the northern point and the celestial body.
Lighting terminology
Brightness Ratio or Contrast – Variations or contrast in the brightness of the visual details of the barrel, such as a white print on a plate.
Candela (cd) is the SI unit of light intensity. The central field is the area of the circle around the fixation point and its diameter, forming an angle of about 2 ° to the eye. Objects in this area are critically visible in both detail and color.
Clear Design Sky – the distribution of the brightness of such a sky is uneven, the horizon is brighter than at the zenith, and when L is the brightness at the zenith, the brightness is at an altitude in the region far from the sun.
The color rendering index (CRI) is a measure of the degree to which the psychophysical color of an object illuminated by a test light source matches the color of the same object illuminated by a reference light source, subject to an appropriate color correction. adaptation.
Correlated color temperature (CCT) (K) – the temperature of the Planck emitter, whose perceived color is closest to the color of the given stimulus at the same brightness and under certain viewing conditions.
Daylight Area – A surface on the work surface illuminated by at least the specified natural light factor, the chat is an area of the corresponding contour.
The Daylight Factor is a measure of the illumination of local natural light at a point in a given plane, expressed as the ratio (or percentage) of illumination at a given point to simultaneous horizontal lighting due to a clear sky in -an outer point open to the whole sky, direct sunlight is excluded.
Daylight penetration – Themaximumdistaoce Eo, in which a certain contour of the natural light factor enters the room.
Sunshine Direct – Sunlight, excluding light from the sky.
External Reflected Component (ERC) – the ratio (or percentage) of that part of daylight illumination at a point on a given plane, which is received by direct reflection from external surfaces, compared to simultaneous external illumination in a plane horizontally throughout the hemisphere. obstructed design of clear sky.
Glare is a condition of vision in which there is discomfort or a decrease in the ability to see significant objects, or both, due to inadequate distribution or range of brightness or due to extreme contrasts in space and time.
illuminance – At a point on a surface, the ratio of the incident light flux to an infinitesimal element of the surface on which the point is in relation to the area of the element.
Internal Reflected Component (IRC) – the ratio (or percentage) of that part of daylight illumination at a point in a given plane that is received by direct or reciprocal reflection from internal surfaces compared to simultaneous horizontal external illumination. plan across the entire hemisphere of a clear, untransformed sky.
Light output ratio (LOR) or Efficiency (YJ) The ratio between the luminous flux emitted by the luminaire and the luminous flux emitted by the lamp (s) (nominal luminous flux). Expressed as a percentage.
A Light Pipe is a channel of highly reflective material capable of transmitting light from one end to the other.
Light Shelf is a natural light system based on the geometry of the same trajectory, used to direct light from the ceiling, project it deeper into space, distribute it from above and diffuse it to obtain a uniform level of light below.
Lumen – SI unit of the luminous flux. The luminous flux is emitted at a right angle (a steradian) by a point source with a uniform intensity of a candle.
Luminance (at a point on the surface in a given direction) (Brightness) – the ratio of the intensity of light in a given direction of an infinitesimal element of the surface that contains the point considered at the orthogonally projected area of the element on a plane perpendicular to the given direction. Unit – candle per square meter (cd / m2.
Luminous flux (<jl) is a quantitative characteristic of radiant flux, which expresses its ability to induce visual sensations, evaluated according to the values of relative light efficacy for light-adapted eyes:
The maintenance factor (d) is the ratio between the average illumination on the work surface after a certain period of use of the luminaire and the average illumination obtained under the same conditions for a new installation.
The meridian is a large circle that passes through the zenith and nadir for a given point of view.
The north and south points are points in the respective directions in which the meridian crosses the horizon.
Orientation of buildings- For non-square buildings, the orientation refers to the normal direction to the long axis. For example, if the length of a building is east-west, its orientation will be north-south.
The peripheral field is the rest of the visual field that allows the observer to be aware of the spatial frames that surround the visible object.
NOTE The central part of the peripheral field, located at an angle of approximately 30 ° to each side of the fixation point, is mainly involved in the perception of strong light.
Reflected glare is a variety of negative effects on visual efficiency and comfort caused by unwanted reflections in and around the work area.
Reflectance is the ratio of the flow of light reflected by the body (with or without diffusion) to the flux it receives.
Reveal – The side of the window opening.
Room index (k,) – Index related to the shape of the rectangular interior.
Sky component (SC) – the ratio (or percentage) of that part of daylight illumination at a point on a given plane, which is received directly from the sky, compared to simultaneous horizontal illumination of the entire hemisphere of the object. unobstructed clear sky design.
Solar load – The amount of heat that enters a building due to solar radiation, which is influenced by orientation, building materials, and reflections of exterior finishes and colors.
The utilization factor (utilization factor) (µ) is the total light flux factor that reaches the working plane.
The visual field is a binocular field of view that includes an area of approximately 120 ° vertically and 160 ° horizontally centered at the point where the eyes are directed. The line connecting the point of attachment and the center of the pupil of each eye is called its main line of sight.
The work plane is the horizontal plane at the level at which one usually works.
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