Term
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Definition
| - light emitted in a specific direction by a source; measured in Candelas (cd) |
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Definition
| – light emitted in all directions by a source; measure in Lumens (lm) |
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Definition
| density of light at any given point on a surface; measured in Footcandles (fc) |
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Definition
| – total quantity of light emitted, reflected or transmitted in all directions; measured in lumens/sq. ft. (lm/ft2) |
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Term
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Definition
| light that is reflected from a surface in a given direction; measured in candelas/sq. ft (cd/ ft2) (p. 121) |
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Term
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Definition
| Light is Measured in what 2 ways? |
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Term
| LUMINOUS INTENSITY DISTRIBUTION CURVE |
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Definition
| Illustrates the pattern of light emitted from the center of the lamp |
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Term
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Definition
represents the distributional intensity of a luminaire (fig. 10.1, p. 122)
[image] |
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Term
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Definition
– represents the distributional intensity of a directional lamp
[image] |
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Term
| POLAR & RECTILINEAR GRAPH |
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Definition
| Luminous Intensity Distribution Curve is measured on these 2 graphs |
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Term
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Definition
| Recommended illuminance values are measured at what height? |
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Term
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Definition
| Recommended levels can be reduced by WHAT for users under 40? |
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Term
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Definition
| Recommended illumenence levels can be increased by up to WHAT?? for users over 55? |
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Term
| ILLUMINANCE CALCULATIONS - SINGLE POINT |
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Definition
Illuminance at a point (footcandles)
Point is directly below the lamp source
FC = I / D2
where I = Intensity found on the Polar or Rectilinear graph for a lamp (candelas)
D = distance from the light source to the point |
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Term
| ILLUMINANCE CALCULATIONS - ANGLE |
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Definition
Illuminance at a point (footcandles)
Point is at an angle to the lamp source
FC =( I / D2 ) x cos Θ (horizontal points)
where Θ = the angle of the object from the nadir or the lamp source |
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Term
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Definition
| is at an angle to the lamp source |
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Term
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Definition
| ??=( I / D2 ) x sinΘ (vertical points) |
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Term
| FORMULA FOR ILLUMINANCE CALCULATIONS |
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Definition
What Calculation -
Takes into consideration:
Number of lamps
Initial Lamp Lumens – provided by manufacturer
LLF – Light Loss Factor = LLD x LDD
LLD – Lamp Lumen Depreciation
LDD – Luminaire Dirt Depreciation
CU – Coefficient of Utilization
Room Cavity Ratio |
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Term
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Definition
| The unit of luminous intensity approximatley equal to the horizontal light output from an ordinary candle |
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Term
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Definition
| = Light Output. In simple terms, Lumens (denoted by lm) are a measure of the total amount of visible light (to the human eye) from a lamp or light source. |
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Term
| What are the varibles in light levels |
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Definition
Nature of the task
the age of the person
the reflectances of the room
the demand for speed and accuracy in performing the task |
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Term
| What sre the four considerationd in light Quality |
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Definition
1. glair
2. contrast
3. uniformity
4. color |
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Term
| What are two types of glare |
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Definition
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Term
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Definition
| when a light source in the field or visioncouses discomfort and interforence with visual task |
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Term
| What does VCP - Visual Comfort Probability |
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Definition
is a metric used to rate lighting scenes.
is a rating on a scale of 0-100 given to indoor fixtures |
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Term
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Definition
| Occures when a light source is reflected from a viewed surface into the eye |
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Term
| What is veiling reflection |
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Definition
| This sometimes is called reflected glare. Another kind of veiling reflection occurs when one looks through a pane of glass |
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Term
| What is contrast when reffering to lighting |
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Definition
| the difference in illumination level between one point and nearby points |
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Term
| What is uniformity when taking about lighting |
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Definition
| which translates to the human perception of how evenly illumination is distributed throughout |
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