Lighting calculations. The Illuminance: (E) شدة الإضاءة =Luminous Flux / area of the...

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Lighting calculations

Transcript of Lighting calculations. The Illuminance: (E) شدة الإضاءة =Luminous Flux / area of the...

Page 1: Lighting calculations. The Illuminance: (E) شدة الإضاءة =Luminous Flux / area of the sphere surface E= Φ /A E= I/ r 2 = lumen/ m 2 = lux.

Lighting calculations

Page 2: Lighting calculations. The Illuminance: (E) شدة الإضاءة =Luminous Flux / area of the sphere surface E= Φ /A E= I/ r 2 = lumen/ m 2 = lux.
Page 3: Lighting calculations. The Illuminance: (E) شدة الإضاءة =Luminous Flux / area of the sphere surface E= Φ /A E= I/ r 2 = lumen/ m 2 = lux.

The Illuminance: (E) شدةاإلضاءة

=Luminous Flux / area of the sphere surface

E=Φ/AE= I/ r2

= lumen/ m2 = lux

Page 4: Lighting calculations. The Illuminance: (E) شدة الإضاءة =Luminous Flux / area of the sphere surface E= Φ /A E= I/ r 2 = lumen/ m 2 = lux.

The luminance (Luminous Intensity) (I) شدة االستضاءة

I= Φ/ω cd Where: ω = solid angle

 = (Φ/A)* r2

= E* r2 Candela

Page 5: Lighting calculations. The Illuminance: (E) شدة الإضاءة =Luminous Flux / area of the sphere surface E= Φ /A E= I/ r 2 = lumen/ m 2 = lux.

Inverse square law: Double the Radius:• Surface area bounded by a solid angle of 1 sr now increases to 4m2

• Luminous flux remains Φ = 1lm• Illuminance E drops from 1 lux to ¼ lux

Page 6: Lighting calculations. The Illuminance: (E) شدة الإضاءة =Luminous Flux / area of the sphere surface E= Φ /A E= I/ r 2 = lumen/ m 2 = lux.

What can we do with this?

It’s the basic building lightingWe can find the illuminance on a desk from a

incandescent light bulb overhead:

Bulb: 60W * 20 lm/W = 1200 lm

1200/4π ≈ 100 cd if point source

Desk : E = 100/22 = 25 lux LUMINOUS EFFICACY Is the ratio of the luminous flux emitted by a lamp to the power taken by it. (unit: LUMENS PER WATT, lm/W)

Page 7: Lighting calculations. The Illuminance: (E) شدة الإضاءة =Luminous Flux / area of the sphere surface E= Φ /A E= I/ r 2 = lumen/ m 2 = lux.

Calculation of point illuminance level:Ep

Which are generated by individual light source:

E = I/r2

But, r = h/ cos (∞)So,

Where, Luminous Intensity(I) Hieght (h) Light Incidence Angle (∞)

E p

= I /h2 cos3 ∞

Page 8: Lighting calculations. The Illuminance: (E) شدة الإضاءة =Luminous Flux / area of the sphere surface E= Φ /A E= I/ r 2 = lumen/ m 2 = lux.

Factors affected on illuminance calculations

1. Room Reflectance The room is considered

to consist of three main surfaces:(a) the ceiling cavity,(b) the walls, and(c) the floor cavity (or the

horizontal working plane).

The effective reflectances of the above three surfaces affect the quantity of reflected light

received by the working plane.

Page 9: Lighting calculations. The Illuminance: (E) شدة الإضاءة =Luminous Flux / area of the sphere surface E= Φ /A E= I/ r 2 = lumen/ m 2 = lux.

2. Luminaire maintenance factor (LMF) is the proportion of the initial light output from a luminaire after a set time to the initial light output from a lamp after a set time.

Three factors must be considered in its determination:

(a) the type of luminaire,

(b) atmospheric conditions, and

(c) maintenance interval.

3. Room surface maintenance factor (RSMF) is the proportion of the illuminance provided by a lighting installation in a room after a set time compared with that occurred when the room was clean.

4. Utilization factor (UF)

is the proportion of the luminous flux emitted by the lamps which reaches the working plane. Factors that affect the value of UF are as follows:

(a) light output ratio of luminaire(b) flux distribution of luminaire(c) room proportions(d) room reflectance(e) spacing/mounting height ratio

Factors affected on illuminance calcuations

Page 10: Lighting calculations. The Illuminance: (E) شدة الإضاءة =Luminous Flux / area of the sphere surface E= Φ /A E= I/ r 2 = lumen/ m 2 = lux.

Lumen Method Calculations

 

Page 11: Lighting calculations. The Illuminance: (E) شدة الإضاءة =Luminous Flux / area of the sphere surface E= Φ /A E= I/ r 2 = lumen/ m 2 = lux.

Where :E = average illuminance over the horizontal working plane    n = number of lamps in each luminaire    N = number of luminaire    F = lighting design lumens per lamp,

i.e. initial bare lamp luminous flux     UF = utilisation factor for the horizontal working plane     LLF = light loss factor     A = area of the horizontal working plane 

Page 12: Lighting calculations. The Illuminance: (E) شدة الإضاءة =Luminous Flux / area of the sphere surface E= Φ /A E= I/ r 2 = lumen/ m 2 = lux.

The Luminous Flux (Φ)= EA/MU

Page 13: Lighting calculations. The Illuminance: (E) شدة الإضاءة =Luminous Flux / area of the sphere surface E= Φ /A E= I/ r 2 = lumen/ m 2 = lux.

Calculate the utilization factor Calculate the Room Factor:

K = 0.8W + 0.2Lhe

Where: W= width of the room

L = length of the room

From the table find “η”

The Luminous Flux (Φ)= EA

η

Page 14: Lighting calculations. The Illuminance: (E) شدة الإضاءة =Luminous Flux / area of the sphere surface E= Φ /A E= I/ r 2 = lumen/ m 2 = lux.

Room Factor

It depends on room dimension

is the proportion of the initial light output from a luminaire after a set time to the initial light output from a lamp after a set time.

Page 15: Lighting calculations. The Illuminance: (E) شدة الإضاءة =Luminous Flux / area of the sphere surface E= Φ /A E= I/ r 2 = lumen/ m 2 = lux.
Page 16: Lighting calculations. The Illuminance: (E) شدة الإضاءة =Luminous Flux / area of the sphere surface E= Φ /A E= I/ r 2 = lumen/ m 2 = lux.
Page 17: Lighting calculations. The Illuminance: (E) شدة الإضاءة =Luminous Flux / area of the sphere surface E= Φ /A E= I/ r 2 = lumen/ m 2 = lux.
Page 18: Lighting calculations. The Illuminance: (E) شدة الإضاءة =Luminous Flux / area of the sphere surface E= Φ /A E= I/ r 2 = lumen/ m 2 = lux.
Page 19: Lighting calculations. The Illuminance: (E) شدة الإضاءة =Luminous Flux / area of the sphere surface E= Φ /A E= I/ r 2 = lumen/ m 2 = lux.
Page 20: Lighting calculations. The Illuminance: (E) شدة الإضاءة =Luminous Flux / area of the sphere surface E= Φ /A E= I/ r 2 = lumen/ m 2 = lux.
Page 21: Lighting calculations. The Illuminance: (E) شدة الإضاءة =Luminous Flux / area of the sphere surface E= Φ /A E= I/ r 2 = lumen/ m 2 = lux.
Page 22: Lighting calculations. The Illuminance: (E) شدة الإضاءة =Luminous Flux / area of the sphere surface E= Φ /A E= I/ r 2 = lumen/ m 2 = lux.
Page 23: Lighting calculations. The Illuminance: (E) شدة الإضاءة =Luminous Flux / area of the sphere surface E= Φ /A E= I/ r 2 = lumen/ m 2 = lux.
Page 24: Lighting calculations. The Illuminance: (E) شدة الإضاءة =Luminous Flux / area of the sphere surface E= Φ /A E= I/ r 2 = lumen/ m 2 = lux.
Page 25: Lighting calculations. The Illuminance: (E) شدة الإضاءة =Luminous Flux / area of the sphere surface E= Φ /A E= I/ r 2 = lumen/ m 2 = lux.
Page 26: Lighting calculations. The Illuminance: (E) شدة الإضاءة =Luminous Flux / area of the sphere surface E= Φ /A E= I/ r 2 = lumen/ m 2 = lux.