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Lighting Design Lecture

Lighting Design Lecture. Common and Recommended Light Levels Indoor. The table below is a guidance for recommended light level in different work spaces:. Design of the Lighting System the lumen method.

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Lighting Design Lecture

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  1. Lighting Design Lecture

  2. Common and Recommended Light Levels Indoor

  3. The table below is a guidance for recommended light level in different work spaces:

  4. Design of the Lighting Systemthe lumen method this is a simplified design approach to enable the designer to achieve an even light distribution in spaces of reasonably simple geometry (i.e. rectangular). • The basis of the lumen method is the following equation: • N - is the number of luminaires required; • E - is the required illuminance (lux); • A - is the area to be lit; • n - is the number of lamps per luminaire; • F - is the lamp lumen output (lumens); • MF - is known as the maintenance factor, which is a combination of three factors; • UF - is the utilisation and is a function of the luminaire properties and room geometry.

  5. length L width W ceiling cavity ceiling plane hm working plane floor cavity Utilisation Factor (UF) • The room geometry is a crucial factor in determining the utilisation factor term in the lumen equation. Several parameters are important. • floor cavity • ceiling cavity • working plane • ceiling plane • hm • length L • width W • In the Lumen method of design the room geometry is characterised by a room index (K):

  6. Maintenance Factor (MF) • The maintenance factor is a value designed to account for the reduction in light output from a lighting system due to: the ageing of the lamps and the accumulation of dirt and dust on the light fittings and room surfaces. The MF is therefore time varying and is the product of 4 factors: • Lamp lumen maintenance factor (LLMF) – a value between 0 and 1 which accounts for the degradation of lamp output over time: • The LLMF for any time t can be obtained from manufacturer’s data

  7. Example A production area in a factory measures 60 m x 24 m. The illumination required for the factory area is 200 lux. • Utilisation factor = 0.4 • Lamp Maintenance Factor = 0.75 • Find the number of lamps required if each lamp has a Lighting Design Lumen (LDL) output of 18,000 lumens.

  8. Solution N = (200 lux x60m x24m) / (18,000 lumens x0.4 x 0.75 ) N =53.33 N = 54 lamps

  9. Spacing distance Mounting Height (Hm) 0.85 metres Working plane height f.f.l. Spacing The spacing to mounting height ratio: S/H

  10. Example 2

  11. The number of lamps in each row can be calculated by dividing the total number of lamps found in example 1 by the number of rows. • Total lamps 54 / 4 = 13.5 goes up to nearest whole number = 14 lamps in each row. • The longitudinal spacing between lamps can be calculated by dividing the length of the building by the number of lamps per row. • Length of building 60 m / 14 = 4.28 metres. • There will be half the spacing at both ends = 4.28 / 2 = 2.14 metres

  12. 60 metres Half Spacing 2.14 metres 4.28 metres 6 m 24 metres Scale 1 cm = 4 metres Factory Plan

  13. Light Fittings 4.28 m 60 metres 6 m 24 metres Scale 1 cm = 4 metres Factory Plan • The total array of fittings can be shown below

  14. In the case of fluorescent luminaires that do not have an axially-symmetrical intensity distribution, maximum spacing infonnation stated in the photometric data may indicate: • Spacing to Height ratio (SHR or S/Hm) is defined as the ratio of the distance between adjacent luminaires (centre to centre), to their height above the working plane. • For a rectangular arrangement of luminaires and by approximation, • where A = total floor area •              N = number of luminaires •              Hm = mounting height Uniformity of illuminance • Spacing to Height Ratio

  15. Maximum spacing information for symmetrical luminaires may be shown in the photometric data as SHR MAX, meaning space-height ratio maximum. • For example, if a SHR MAX 1.4is stated for the luminaire in last Figure and the mounting height of luminaire above the working plane is 1.9 m then the maxImum spacing on either direction can be calculated as follows:

  16. In these circumstances, three conditions must be complied with: • 1- The spacing in the transverse direction (SHR TR) must not exceed SHR MAX TR stated. • 2- The spacing in the axial direction (SHR AX) must not exceed the SHR MAX stated. • 3- The actual spacings in the two direction (SHR AX & SHR TR) when multiplied together must not exceed ( SHR MAX ) 2

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