Lecture 2 Flashcards
(47 cards)
What are the types of lighting schemes?
- Direct lighting
- Semi-direct lighting
- Indirect lighting
- Semi-indirect lighting
- General lighting
These schemes define how light is distributed in a space.
What is Direct Lighting?
A lighting scheme where more than 90% of total light flux falls directly on the working plane, causing hard shadows and glare.
It is mainly used for industrial and general outdoor lighting.
What percentage of light flux is used in Semi-Direct Lighting?
60 to 90% of total light flux falls downwards directly.
Remaining light is used to illuminate the ceiling and walls.
Describe Indirect Lighting.
More than 90% of total light flux is thrown upwards to the ceiling for diffuse reflection, minimizing glare.
The ceiling acts as the light source.
What characterizes Semi-Indirect Lighting?
60 to 90% of total light flux is thrown upwards for diffuse reflection, with the rest reaching the working plane directly.
It provides soft shadows and is glare-free.
What is General Lighting?
A scheme using lamps made of diffusing glass that provides nearly equal illumination in all directions.
It is designed to illuminate a space uniformly.
What are the key requirements for a lighting scheme design?
- Provide adequate illumination
- Provide uniform light distribution
- Provide suitable light color
- Avoid glare and hard shadows
These factors ensure effective lighting in a space.
What is the importance of Illumination Level?
It is crucial for visibility as it determines how well we can see our surroundings.
Illumination is necessary for objects to appear bright.
What is the typical illumination level for a Living Room?
300 Lux
This is the standard measure for adequate lighting in living areas.
List factors for proper illumination.
- Uniformity of illumination
- Colour of light
- Shadows
- Glare
- Mounting height
- Spacing of luminaires
- Color of surrounding walls
These factors influence the overall effectiveness of lighting.
What is the Watts per square metre method?
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It is a ‘rule of thumb’ method for rough calculations of lighting requirements based on watts per square metre.
It assumes an average figure of overall efficiency.
What is the Lumen or light flux method?
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A method used when sources of light produce approximate uniform illumination over the working plane.
It is useful for estimating average values.
What does the Point to point or inverse-square law method estimate?
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The illumination at a point due to one or more sources of light, given their candle powers.
This method focuses on specific points of illumination.
Fill in the blank: The required illumination on the working plane in Example 1 is _______ lux.
75 lux
This value is crucial for calculating the number of lamps needed.
What is the mounting height in Example 1?
4 meters
This height affects the calculation of required lamp wattage.
How is total wattage required calculated in Example 1?
N = A x E / (F x MF x UF)
Where N is total wattage, A is area, E is illumination, F is lumens, MF is maintenance factor, and UF is utilization factor.
What is the wattage of each lamp in Example 1?
Approximately 200W
This is calculated based on the total wattage divided by the number of lamps.
Fill in the blank: In Example 2, the average illumination required is _______ lux.
100 lux
This value is essential for determining lamp requirements.
What is the coefficient of utilization in Example 2?
0.4
This factor influences the efficiency of the lighting system.
What is the luminous efficiency in Example 2?
16 lumens per watt
This value is critical for calculating the total wattage required.
What is the formula for calculating the number of lamps in Example 2?
N = A x E / (F x MF x UF)
This formula is used to determine the total number of lamps needed.
What is the wattage of each lamp in Example 2?
Approximately 500W
This is based on the total wattage divided by the number of lamps.
What is the significance of the depreciation factor in lighting calculations?
It accounts for the decrease in light output over time due to maintenance factors.
The depreciation factor is the inverse of the maintenance factor.
What are the types of lighting schemes?
- Direct lighting
- Semi-direct lighting
- Indirect lighting
- Semi-indirect lighting
- General lighting
These schemes define how light is distributed in a space.
