Your SlideShare is downloading.
×

×

Saving this for later?
Get the SlideShare app to save on your phone or tablet. Read anywhere, anytime – even offline.

Text the download link to your phone

Standard text messaging rates apply

Like this presentation? Why not share!

- Commercial Project by Ckurdi 734 views
- Illumination - Method of calculation by Vijay Raskar 24792 views
- IESNA lighting handbook by Carlos Vázquez Vá... 19260 views
- INTERIOR LIGHTING DESIGN A STUDENT'... by no suhaila 8179 views
- Calculations of illumination by Andrew Aung 1031 views
- Illumination Lighting by Vijay Raskar 6646 views
- Electrical Lighting & Cable Selection by Denuka 2970 views
- Laws of illuminations by Vijay Raskar 10675 views
- Lighting design considerations by mominzaki 4602 views
- Lighting Powerpoint by shawn8492 20015 views
- Illumination - Types of lamps by Vijay Raskar 8977 views
- Different types of lamps by qwertyuidhfjkdsjhhb 6323 views

3,657

Published on

coefficient of uti;ization calculation is explained in the presentation

coefficient of uti;ization calculation is explained in the presentation

No Downloads

Total Views

3,657

On Slideshare

0

From Embeds

0

Number of Embeds

2

Shares

0

Downloads

138

Comments

0

Likes

5

No embeds

No notes for slide

- 1. AWP x EWP No. of = luminaires (lumens/lamp) x (lamps/luminaires) x CU x LLFTOTAL The coefficient of utilization is a factor used to determine the efficiency of a lighting fixture in delivering light for a specific application The coefficient of utilization is determined as a ratio of light output from the luminaire that reaches the workplane to the light output of the lamps alone Coefficient of Utilization (CU)
- 2. Coefficient of Utilization (CU) Factors influencing coefficient of utilization: The efficiency of the luminaire The luminaire distribution The geometry of the space The reflectance's of the room surface Each luminaire has its own CU table specific to that luminaire’s light distribution and efficiency. CU values are listed in tables for different room geometries and room surface reflectance.
- 3. For a given room, the cavity ratios are in direct proportion to their respective cavity heights. For the case where the luminaires are mounted on the surface of the ceiling or are recessed into the ceiling, the ceiling cavity ratio is zero. It is necessary to convert the actual ceiling reflectance into an effective ceiling cavity reflectance (pCC) and the actual floor reflectance must be converted to an effective floor cavity reflectance (pFC).
- 4. CU Determination Step 1. Determine the room cavity ratio using the equation below Room cavity height (hRC) = Luminaire height – Workplane height RCR = 5 x Room cavity height (Length + Width) Length x Width
- 5. Step 2. Since the Lumen Method considers what occurs only within the room cavity, the ceiling and floor reflection factor are replaced with their effective reflectances. Ceiling reflection factor: 70% For very light colours and white 50% For light colours 30% for medium shades Wall reflection factor: 50% For light colours and white 30% For medium shades 10% For dark shades
- 6. To find the effective reflectance of a floor or ceiling cavity, find the floor cavity ratio and ceiling cavity ratio using the equations below
- 7. • Step 3. Find the effective cavity reflectances using cavity surface reflectances.
- 8. Step 4. Once all room cavity reflectances and the room cavity ratio are known, the CU value can be determined by selecting the appropriate value from the luminaire’s CU table.
- 9. Example 1 Classroom 20’ x 27’ x 12’ E=50 fc WP= 2’-6” AFF ρc= 80% hcc= 0.0’ ρw= 50% hrc= 9.5’ ρf= 20% hfc= 2.5’ fixture: fluorescent (#38) maintenance: yearly replacement: on burnout voltages & ballast: normal environment: medium clean
- 10. Example 1 Confirm fixture data S: T.15.1 p. 641
- 11. Example 1 Complete #1-6
- 12. Example 1 7. Determine lumens per luminaire Obtain lamp lumens from manufacturer’s data (or see Stein: Chapter 12) S: T. 12.5 p. 546
- 13. Lumen Flux Method 8. Record dimensional data 20’ 27’ 0’ 9.5’ 2.5’ ρc= 80% ρw= 50% ρf= 20%
- 14. Coefficient of Utilization Factor(CU) Calculation 9. Calculate Cavity Ratios
- 15. Example 1: Cavity Ratios CR = 5 H x (L+W)/(L x W) RCR = 5 Hrc x (L+W)/(LxW) = 4.1 CCR = 5 Hcc x (L+W)/(LxW) = 0 FCR = 5 Hfc x (L+W)/(LxW) = 1.1
- 16. Coefficient of Utilization Factor(CU) Calculation 10. Calculate Effective Ceiling Reflectance
- 17. 3. Obtain effective ceiling reflectance: Example 1: Coefficient of Utilization (CU) S: T.15.2 p. 667
- 18. Example 1 11. Calculate Effective Floor Reflectance Stein: T.15.2 P. 666
- 19. 3. Obtain effective ceiling reflectance: Example 1: Coefficient of Utilization (CU) S: T.15.2 p. 667 CU= 0.19 0.20
- 20. Example 1 12. Select CU from mfr’s data or see
- 21. CU=0.32 Example 1: Coefficient of Utilization (CU) RCR CU 4.0 0.39 4.1 X 5.0 0.35 CU= 0.386 S: T.15.1 p. 641

Be the first to comment