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___________________________________________
Questions related to specific materials, methods, and services will be addressed at the conclusion of this presentation.

3. Acuity Brands Lighting
Task – Surround –Ambient Lighting
Peter Ngai, PE, LC, FIES
Acuity Brands Lighting
April 27th, 2016

4. Abstract:
Task –Ambient lighting provides energy saving but space surrounding the users can be dim and uninviting. This study researched into the proposal of an additional Surround Layer of light. That is, Task-Surround-Ambient system. It examined in a simulated environment, illumination requirements, dimensionality and appearance of the space by the use of Vector/Scalar and Task/Vertical Illumination Ratios. They were evaluated under several illuminance requirements, different Task-Surround proportion combinations and various sources sizes of Surround Light. The results showed that by adding a Surround Light Layer, visual quality of space surrounding the users can be enhanced. Energy savings were also valuated under various illuminance conditions and physical layouts. They showed that Task-Surround-Ambient system achieves energy savings.

5. LEARNING OBJECTIVES:
Identify the strength and weaknesses of Total Ambient and Task-Ambient Lighting, and introduce the concept of Task- Surround – Ambient Lighting
Create an analytic model and introduce the lighting metrics for lighting comparisons
Compare Lighting Quality of Total Ambient, Task-Ambient and Task- Surround – Ambient Lighting
Compare Energy Savings for Total Ambient, Task-Ambient and Task- Surround – Ambient Lighting
Practical implementations of Task- Surround – Ambient Lighting

6. Ambient Lighting 40 fc from ambient lighting 40 fc total @ desktop
Lighting quality: glare-free & uniformly illuminated, reduced dimensionality and personalization

7. Low Ambient –Task Lighting
10 fc from
Ambient lighting
30 fc from task lighting
40 fc desktop
Lighting quality: low energy costs with high horizontal workplane illumination, but lower visibility of vertical elements or faces, less dimensionality and sharper shadows. Space rendered dingy and uninviting

8. Low Ambient –Surround –Task lighting Solution
10 fc from
Ambient lighting
SURROUND LIGHTING
30 fc from surround +
Task lighting
40 fc
Lighting quality: added layer of surround light for dimensionality and interaction. Enhance the visual quality of the immediate space surrounding the users

10. This Presentation is a conceptual comparison of Task –Surround –Ambient Lighting System to Total Ambient and Task-Ambient Lighting Systems In a Simulated Environment

11. The Analytic Model
Room Size: ’ X 32’X 10’ 80%, 50% and 20% reflectance Personal Space: ’X 8’X5’ a work station in the middle of the room Task Area : ’ diameter and 2.5’high with 50% reflectance circular table

12. Luminous intensity level for each layers adjusted separately
Lighting Layouts
Light sources: ” X 4” diffuser panels for all three separate layers of lighting.
Luminous intensity level for each layers adjusted separately
Ambient Lighting Layer -225 panels spaced evenly
Surround Lighting Layer - 2’x2’ grid of 25 diffusers at 6’ height over the desk
Task Lighting Layer - 21 diffusers mounted at 6” above the task surface
It should be understood that the use of 4” X 4” luminous panels and the layouts of the panels were to reduce the analytic complexity. The luminous panels for task lighting layer were treated as photometric entities, and not as solid objects.

13. Physical Layout of the Simulated Space
Ambient Lighting layer
Surround Lighting layer
Task Lighting layer
10 FT
Task Surface
5 FT
6 FT
8 FT

14. Lighting Criteria Task illumination @ desktop = 400 Lux
Low Ambient illumination = 100 Lux
Two location points were analyzed:
1st Point - 10 inches away from the edge of the table and 4ft-2in from the floor.
2nd Point - center of the space at the same height

15. Physical Layout of the Simulated Space
Side Location Point
Center Location Point
20 in

16. Lighting Criteria Lighting criteria were evaluated by two factors:
The ratio of Vertical two location points facing the center of personal space to that of task surface illumination needs to be within a ratio of 1:3 or better. That is, lower than 1:3
The points need to have acceptable Vector/Scalar Illumination ratios 1> V/S <2

17. Lighting Effects at Different Vector/Scalar Ratios
(Dimensionality)
Vector/Scalar Ratio
Flow of Light
Appearance
3.5
Dramatic
Theatrical
3.0
Very Strong
Strong Contrast, Details not discernable
2.5
Strong
Suitable for display, too harsh for faces
2.0
Moderately Strong
Pleasant for distant face
1.5
Moderately Weak
Pleasant for near faces
1.0
Weak
Soft Lighting for subdued effects .5
Very Weak
Flat, shadow free lighting
Note: Values within bracket should not be ranked in terms of desirability. It is a matter of personal preference/application.
CR 1:3 or 1<V/S<2.0 should not be taken literally

18. Magnitude of the illumination Vector,
Vector/Scalar Ratio Calculation
Let E(x) and E(-x) be the two opposing Illumination on the X axis
E(y) and E(-y) be the two opposing Illumination on the Y axis
E(z) and E(-z) be the two opposing Illumination on the Z axis 
Then, ʽE(x) = E(x) - E(-x) is the Illumination Vector on the X axis
ʽE(y) = E(y) - E(-y) is the Illumination Vector on the Y axis
ʽE(z) = E(z) - E(-z) is the Illumination Vector on the Z axis
|E|= √(ʽE(x) ʽE(y) ʽE(z) 2 ) (1)
The Scalar Illumination Esr , Esr = |E|/4 + (~E(x) + ~E(y) + ~E(z) )/3 (2)
Where ~E(x) is the lesser of E(x) and E(-x)
~E(y) is the lesser of E(y) and E(-y)
~E(z) is the lesser of E(z) and E(-z)
From Equation (1) and (2), Vector/Scalar Ratio = |E|/ Esr
Magnitude of the illumination Vector,

19. Lighting Scenarios 1 400 Scenario Ambient Layer Surround Layer
Scenario 
Ambient Layer
Surround Layer
Task Layer
Total Ambient (LUX) 1
400

20. Lighting Scenarios Task-Ambient (LUX) 2 100 300 Scenario Ambient Layer
Scenario 
Ambient Layer
Surround Layer
Task Layer
Task-Ambient (LUX) 2
100
300

21. Task-Surround- Ambient
Lighting Scenarios
Scenario 
Ambient Layer
Surround Layer
Task Layer
Task-Surround- Ambient
(LUX) 3
100
200 4
150 5

22. Surround –Ambient (LUX)
Lighting Scenarios
Scenario 
Ambient Layer
Surround Layer
Task Layer
Surround –Ambient (LUX) 6
100
300

23. Task-Surround- Ambient
6 Lighting Scenarios
Scenario 
Ambient Layer
Surroun d Layer
Task Layer
Total Ambient 1
400
Task-Ambient 2
100
300
Task-Surround- Ambient 3
200 4
150 5
Surround – Ambient 6

24. Results Analysis

25. for Task Surface Illumination of 400 Lux
Data on Computations of Illumination, Contrast Ratio and Vector/Scalar Ratios
for Task Surface Illumination of 400 Lux

26. 1:1.8
1:1.6
1:5.5
1:4.9
1:3.9
1:2.7
1:2.8
1:2.2
1:2.3
1:1.8
1:1.8
1:1.4

27. What can we tell from the above results?
1:1.8
1:1.6
1:5.5
1:4.9
1:3.9
1:2.7
1:2.8
1:2.2
1:2.3
1:1.8
1:1.8
1:1.4
What can we tell from the above results?

28. 1:1.8
1:1.6
1:5.5
1:4.9
1:3.9
1:2.7
1:2.8
1:2.2
1:2.3
1:1.8
1:1.8
1:1.4
Why?

29. E2(X) @ Center location Pt
Total Ambient and Task - Ambient
E1(X)
E2(X)
Side Location Pt
>
Center location Pt

30. E2(X) @ Center location Pt
Task-Surround-Ambient
E1(X)
E2(X)
Side Location Pt
>
Center location Pt

31. S SS
1:1.8
1:1.6
1:5.5
1:4.9
1:3.9
1:2.7
1:2.8
1:2.2
1:2.3
1:1.8
1:1.8
1:1.4
Why?

32. V/S @ Center location Pt
Total Ambient and Task - Ambient
ʽE(x) = E(x) - E(-x)
ʽE(z) = E(z) - E(-z)
E2(+Z)
E1(+Z)
|E|= √(ʽE(x) 2 + ʽE(z) 2 )
E2(-X)
E1(-X)
E2(+X)
E1(+X)
|E1|
>
|E2|
E1(-Z)
E2(-Z)
Side Location Pt
>
Center location Pt

33. 1:1.8
1:1.6
1:5.5
1:4.9
1:3.9
1:2.7
1:2.8
1:2.2
1:2.3
1:1.8
1:1.8
1:1.4
Why?

34. V/S @ Center location Pt
Task-Surround -Ambient
ʽE(x) = E(x) - E(-x)
ʽE(z) = E(z) - E(-z)
E2(+Z)
E1(+Z)
|E|= √(ʽE(x) 2 + ʽE(z) 2 )
E1(+X)
E2(-X)
E2(+X)
|E1|
|E2|
E1(-Z)
E2(-Z)
Side Location Pt
Center location Pt

35. What did we just learn?
1) SLP illumination is higher than CLP
2) SLP CR is lower than CLP
3) SLP V/S is lower than CLP

36. What can we tell from the above results?
Total Ambient Vs Task - Ambient Lighting
at 400 lux Task Surface Illumination
Total ambient lighting is better in meeting criteria than task- ambient lighting for both vertical illumination contrast and V/S ratios. This is typical general lighting system that normally found in an open office or a classroom.
Task – ambient lighting appeared to be dingy and dark. The contrast ratios is well below 3:1. While the V/R ratio for the side location point is acceptable, the low illumination renders the condition to be uninviting and dark.
What can we tell from the above results?

37. at 400 lux Task Surface Illumination
Total Ambient Vs Task - Ambient Lighting
at 400 lux Task Surface Illumination
Total ambient lighting is better in meeting criteria than task- ambient lighting for both vertical illumination contrast and V/S ratios. This is typical general lighting system that normally found in an open office or a classroom.
Task – ambient lighting appeared to be dingy and dark. The contrast ratios is well below 3:1. While the V/R ratio for the side location point is acceptable, the low illumination renders the condition to be uninviting and dark.
Total ambient lighting is better in meeting criteria than task- ambient lighting for both vertical illumination contrast and V/S ratios. This is typical general lighting system that normally found in an open office or a classroom.
Task – ambient lighting appeared to be dingy and dark. The contrast ratios is well below 3:1. While the V/R ratio for the side location point is acceptable, the low illumination renders the condition to be uninviting and dark.

38. What can we tell from the above results?
Total Ambient Vs Task-Ambient Vs Surround- Ambient at 400 lux Task Surface Illumination
The vertical illumination was high and well within the 3:1 contrast ratio. This resulted in brightening up of the entire personal space.
V/R ratios were high. it drastically increased the dimensionality.. In fact, some individuals might find V/S ratio of 2.5 at Center Location Position as too high. higher V/S ratios
Side Location point has higher Vertical Illumination and low CR.
What can we tell from the above results?

39. Total Ambient Vs Task-Ambient Vs Surround- Ambient at 400 lux Task Surface Illumination
The vertical illumination was high and well within the 1:3 contrast ratio. This resulted in brightening up of the entire personal space.
V/R ratios were high. it drastically increased the dimensionality. In fact, some individuals might find V/S ratio of 2.5 at Center Location Position as too high.
Side Location point has higher Vertical Illumination and low CR.

40. What can we tell from the above results?
Lighting comparisons for Surround Lighting Layer @400 Lux Task Surface Illumination for different ambient/surround/task light levels
What can we tell from the above results?

41. Lighting comparisons for Surround Lighting Layer @400 Lux Task Surface Illumination for different ambient/surround/task light levels
The higher was the surround light contribution, the higher was the vertical illumination
Contrast ratios from all combinations were better than 1:3 once the combination of Ambient/Surround/Task ratio reached 100/100/200

42. What can we tell from the above results?
Lighting comparisons for Surround Lighting Layer @400 Lux Task Surface Illumination for different ambient/surround/task light levels
The higher was the surround light contribution, the higher was the vertical illumination
Contrast ratios from all combinations were better than 3:1 once the combination of Ambient/Surround/Task ratio reached 100/100/200.
V/S ratios moved higher as surround lighting contribution increases.
The results showed that with a wide range of adjustments for task and surround lighting layers, a user could achieve a satisfactory lighting condition for his/her preference.
What can we tell from the above results?

43. Lighting comparisons for Surround Lighting Layer @400 Lux Task Surface Illumination for different ambient/surround/task light levels
The higher was the surround light contribution, the higher was the vertical illumination
Contrast ratios from all combinations were better than 3:1 once the combination of Ambient/Surround/Task ratio reached 100/100/200.
V/S ratios moved higher as surround lighting contribution increases.
The results showed that with a wide range of adjustments for task and surround lighting layers, a user could achieve a satisfactory lighting condition for his/her preference.
Contrast ratios moved higher as surround lighting contribution increases.
v/s ratios from all combinations were between 1 and 2 once the combination of Ambient/Surround/Task ratio reached 100/100/200.
The results showed that with a wide range of adjustments for task and surround lighting layers, a user could achieve a satisfactory lighting condition for his/her preference.

44. What can we tell from the results?
400 Lux
Effect of Task Surface Illumination Levels
What can we tell from the results?
The higher was the surround lighting portion, the higher was the vertical illumination.
For scenarios involving surround lighting layer, similar to 400 lux task surface illumination case, the side location points had higher vertical illumination
When comparing across task surface illumination levels, the lower was task surface illumination, the more the CR values moved towards compliance. The reason was that at lower surface illumination level, Ambient Lighting Layer that was held to a constant value, contributed a larger proportion of the total task surface illumination.
300 Lux
200 Lux

45. Effect of Task Surface Illumination Levels
400 Lux
300 Lux
200 Lux
Trends for CR were the same as that at 400 lux. The higher was the surround lighting portion, the higher was the vertical illumination and V/S ratio.
For scenarios involving surround lighting layer, similar to 400 lux task surface illumination case, the side location points had higher vertical illumination.
When comparing across task surface illumination levels, the lower was task surface illumination, the more the values moved towards compliance. The reason was that at lower surface illumination level, Ambient Lighting Layer that was held to a constant value, contributed a larger proportion of the total task surface illumination.

46. What can we tell from the results?
400 Lux
What can we tell from the results?
Effect of Task Surface Illumination Levels
The higher was the surround lighting portion, the higher was the V/S.
For scenarios involving surround lighting layer, similar to 400 lux task surface illumination case, the side location points had higher V/S
When comparing across task surface illumination levels, the lower was task surface illumination, the more the V/S values moved towards compliance. The reason was that at lower surface illumination level, Ambient Lighting Layer that was held to a constant value, contributed a larger proportion of the total task surface illumination.
300 Lux
200 Lux

47. Effect of Task Surface Illumination Levels
VECTOR/SCALAR
Trends in V/S same as that at 400 lux. The higher was the surround lighting, the higher was V/S.
Similar to 400 lux task surface illumination case, the side location points had lower V/S ratio.
When comparing across task surface illumination levels, the lower was task surface illumination, the more C/S values moved towards compliance. The reason was the same as Vertical Illumination
All 3 combinations of Ambient /Surround/Task location points for all three light levels within the acceptable range both in terms of Illumination Contrast Ratios and V/S ratios.
The results showed that the concept of Task-Surround-Ambient worked for a wide range of task surface illumination.

48. What can we tell from the above results?
Effect of Surround Lighting Layer Size
Vertical Illumination
Center Location Point
Vertical Illumination
Side Location Point
What can we tell from the above results?

49. E1(X) < E2(X) Vertical Illumination Center Location Point
Equal Light Output
For center point location, Larger size, greater Vertical Illumination, why?
E1(X)
E2(X)
E1(X) < E2(X)
For CLP, the larger was the size of surround light source, the greater was the vertical illumination. Opposite effect on Vector/Scalar ratios. The smaller was the area of the Surround Lighting layer, the higher was the V/R ratio.
For side location point, Vertical Illumination and V/S ratio did not affect appreciably, by different surround light source sizes.
For all location points, the larger the size of surround light the better was the CR and V/S Ratio. More pronounce with center location points more so than side location points.
Smaller surround light size, creates greater luminance and high V/R ratio. This produces glary, hash and dramatic lighting environment. Not a good approach for surround lighting layer. As the surround source size increases, luminance intensity reduces and the environment gets softer and more comfortable.
Results and assertions from task surface illumination of 400 lux can be extended to lower task surface illumination level. When the overall task surface illumination is lowered, the proportion of ambient lighting layer contribution to task surface illumination increases. This will pull the results closer to that of the ambient only system. Hence, at lower task illumination, various sizes of Surround Lighting Layer will behave similarly to that of at 400 lux and with more ease of compliance.

50. E1(X) ≈ E2(X) Vertical Illumination Side Location Point
Equal Light Output
E1(X)
E2(X)
E1(X) ≈ E2(X)
Side point location, different sizes, similar Vertical Illumination, why?

51. Effect of Surround Lighting Layer Size
Vertical Illumination
Center Location Point
Vertical Illumination
Side Location Point
For center location point, the larger was the size of surround light source, the greater was the vertical illumination.
For center location point, the more surround light, the more was the vertical illumination.
For side location point, different surround light source sizes did not affect Vertical Illumination appreciably.
For side location point, the more is surround light, the greater was the vertical illumination.

52. What can we tell from the above results?
Effect of Surround Lighting Layer Size
Vector/Scalar Ratio
Side Location Point
Vector/Scalar Ratio
Center Location Point
What can we tell from the above results?

53. V/S(1) > V/S(2) Vector/Scalar Ratio Center Location Point
Equal Light Output
E2(Z)
E1(Z)
E1(Z) > E2(Z)
V/S(1) > V/S(2)
For center point location, smaller size, greater Vertical Illumination, why?

54. Vector/Scalar Ratio Side Location Point
Equal Light Output
E1(Z)
E2(Z)
E1(Z) ≈ E2(Z)
V/S(1 ≈ V/S(2)
Side point location, different sizes, similar Vertical Illumination, why?

55. Effect of Surround Lighting Layer Size
Vector/Scalar Ratio
Center Location Point
Vector/Scalar Ratio
Side Location Point
For center location point, the smaller was the area of the Surround Lighting layer, the higher was the V/R ratio.
For center location point, the more was surround light, the greater was the V/R ratio.
For side location point, different surround light source sizes did not affect V/R appreciably.
For side location point, the more surround light, the greater was the V/R ratio.

56. Effect of Surround Lighting Layer Size
Smaller surround light size, creates greater luminance and high V/R ratio. This produces glary, hash and dramatic lighting environment. Not a good approach for surround lighting layer. As the surround source size increases, luminance intensity reduces and the environment gets softer and more comfortable.
2. Results and assertions from task surface illumination of 400 lux can be extended to lower task surface illumination level. When the overall task surface illumination is lowered, the proportion of ambient lighting layer contribution to task surface illumination increases. This will pull the results closer to that of the ambient only system. Hence, at lower task illumination, various sizes of Surround Lighting Layer will behave similarly to that of at 400 lux and with more ease of compliance.

57. Relative Energy Consumptions
5, 9 and 12-Stations Layout

58. What can we tell from the above results?
Relative Energy Consumptions
What can we tell from the above results?

59. Relative Energy Consumptions
Total Ambient Lighting had the highest energy consumption for all three workstation layouts and all lighting scenarios. Task – Ambient Lighting consumed the least.
The higher was the task surface illuminance, the higher was the relative energy savings. This was true for all lighting scenarios.
The lower was the density of workstations, the higher was the energy savings.
Energy savings for Task-Surround-Ambient lighting system compared favorably with Task-Ambient system. This was especially true in case of high task surface illumination and low density workstation layout.
As the proportion of surround light increased, the energy savings decreased.

60. Implementing Low Ambient –Surround –Task lighting Solutions

61. Implementing Low Ambient –Surround –Task lighting Solutions

62. Implementing Low Ambient –Surround –Task lighting Solutions

64. Conclusions
The addition of surround lighting layer is effective in enhancing dimensionality and the appearance of space over and beyond what Task- Ambient Lighting can offer.
This is valid though a range of task surface illumination and surround light source sizes.
The study also taught the idea of adjusting to different combinations of Task and Surround Lighting Layers which allows the user to tune to for different lighting applications as well as personal preferences.
This study showed energy savings for Task- Surround – Ambient Lighting compared favorably to that of Task-Ambient Lighting system.

65. Discussions
The study was anchored with two lighting measures. illumination ratio and the Vector/Scalar Ratio The first criterion is straight forward and generally accepted. As for the second criterion, there are a number of other models including, Cylindrical /Horizontal Illumination Ratio, Vector/Cylindrical Illumination Ratio and Target/Ambient illumination Ratio (TAIR) among others. Vector/Scalar Ratio is probably the most recognized metric. Hence this study adopted this criterion. While other metrics will yield different numeric results, but the essences and trends investigated by this study using Vector/Scalar should be similar.
This study was based on a specific set of lighting conditions. Different sets of input will not replicate identical numeric values. However, this should not alter the fundamental results and conclusions of this study. The main trust of this paper is to gain insight of the interplay among the three layers of light. Hence, the study should be viewed in a conceptual perspective rather than quantitative precision. When a specific lighting layout is known, then the lighting can be evaluated for that specific condition.

66. Discussions
The results of this paper is not limited to facial modeling. It is valid to extend to appearance of any objects within the personal space. Hence Task - Surround concept is just as applicable with multiple persons interacting within the space, as with a single person working in solitude.
It is important to point out that this study focused on the visual appearance surrounding the task area by means of Contrast Ratio and Vector/Scalar Ratio. Other important lighting quality factors such as task visibility, visual comfort, and health and wellbeing aspects though not the subject of our study, should always be considered.
Final, while the study was done with three discrete layers of lighting for clarity, in practice, it is conceivable that one luminaire through its light distributions and positioning, can function as more than one layer of light.

67. Thank You