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

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.

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

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

Low Ambient –Task Lighting 10 fc from Ambient lighting 30 fc from task lighting 40 fc total @ 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

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

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

The Analytic Model Room Size: 32’ X 32’X 10’ 80%, 50% and 20% reflectance Personal Space: 8’X 8’X5’ a work station in the middle of the room Task Area : 4’ diameter and 2.5’high with 50% reflectance circular table

Luminous intensity level for each layers adjusted separately Lighting Layouts Light sources: 4” 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.

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

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

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

Lighting Criteria Lighting criteria were evaluated by two factors: The ratio of Vertical Illumination @ 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

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

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) 2 + ʽE(y) 2 + 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,

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

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

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

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

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

Results Analysis

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  

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? 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?

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?

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

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

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?

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) V/S @ Side Location Pt > V/S @ Center location Pt

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?

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) V/S @ Side Location Pt V/S @ Center location Pt

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

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?

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.

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?

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.

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?

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

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?

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.

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

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.

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

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.

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?

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.

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?

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.

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?

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?

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?

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.

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.

Relative Energy Consumptions 5, 9 and 12-Stations Layout

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

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.

Implementing Low Ambient –Surround –Task lighting Solutions

Implementing Low Ambient –Surround –Task lighting Solutions

Implementing Low Ambient –Surround –Task lighting Solutions

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.

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.

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.

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