impact of interior design changes on office based lighting schemes

Impact of Interior Design Changes on Office-Based Lighting Schemes

PCN224-Applied Lighting Jordan Agustin

Project Aim

○ Investigation how various interior design changes affect lighting scheme performance.

○ Results used to develop a “Design Issues Guide” on how to minimise negative impact on the lighting scheme when making interior fitout changes.

Project Scope

○ Standard Office Fitout ● 2.7m ceiling ht. ● Task Lighting provided by single luminaire type

(recessed fluorescent) – No accent/specialty lighting ● 350m2 floor space ● Windows on 3 sides, services behind 4th. ● Electric Lighting only considered

○ Variations of design elements, and the study of the effects on Illuminance and Uniformity

Design Variables

○ Wall colour and texture changes (reflectance) ○ Desk Colour changes (reflectance) ○ Partition height changes (Obstruction) ○ Partition material and colour changes

(reflectance) ○ Desk/partition layout change (obstruction) ○ Floor coverings (reflectance)

Space Configuration

○ Std Grid Configuration

○ Windows on 3 sides

Base Scheme Performance

○ Performance specs allow for MF = .57 (spot replacement, OR

○ Group replacement, E(avge) = 320lx ● Not critical what the specs are, only need to know

what they are to measure change

E(max) E(min) E(avge)U(min/ avge) E(av direct) E(av indirect)

502 337 398 0.85 341 57

Design Change – Colour Scheme

○ Very simple modification ● Huge reflectance variation possible (ρ=7% - 90%+) ● AS1680.1:2006 Section 6.3 does recommends wall

reflectance be less < 0.8 and >0.3 ● Modern design trends - may not always select

compatible colours.


Average Illuminance at the Working Plane vs. Wall Reflectance

0

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0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Wall Reflectance

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E(avge)E(Indirect)Poly. (E(avge))Poly. (E(Indirect))


Uniformity at the Working Plane vs. Wall Reflectance

0.8

0.81

0.82

0.83

0.84

0.85

0.86

0.87

0.88

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Wall Reflectance

Wor

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Pla

ne U

nifo

rmity

U(min/avge)Poly. (U(min/avge))


○ Decrease wall reflectance by 50%: ● Average illuminance -6%, ● Uniformity -2%

○ Wall reflectance and colour selection does not significantly affect average illuminance and uniformity.

○ Other negative design implications of excessively high or low surface reflectances

Design Change – Desk Colour

○ A change in colour scheme is also likely to mean that furniture colours will change.

○ Desktops in an open plan office environment represent a large surface area ● Direct illumination reflected back up onto ceiling and

walls, contributing to the indirect component ● Wide selection of laminates and finishes available

(ρ=15% - 80%+)


Average Illuminance at the Working Plane vs. Desk Reflectance

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100

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450

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Desktop Reflectance

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E(avge)E(Indirect)Poly. (E(avge))Poly. (E(Indirect))


Uniformity at the Working Plane vs. Desk Reflectance

0.8

0.81

0.82

0.83

0.84

0.85

0.86

0.87

0.88

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Desktop Reflectance

Wor

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rmity



○ Desktop reflectance does not significantly affect average illuminance and uniformity.

○ Affecting the indirect flux component by increasing surface reflectances can see average illuminance go up, but uniformity decreases.

○ Other negative design implications of excessively high or low surface reflectances

Design Change – Partitions

○ Introduction of vertical obstructions above the working plane.

○ Design changes so far have affected the indirect component only

○ Partitions will have an effect on direct illumination as well as indirect.


Average Illuminance at the Working Plane vs. Partition Ht. above Working Plane

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0 0.1 0.2 0.3 0.4 0.5 0.6 0.7

Partition Height Above Work Plane

Wor

kpla

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ce

E(avge, ρ=.2)

E(avge,ρ=.5)

E(min, ρ=.2)

E(min, ρ=.5)

Poly. (E(avge, ρ=.2))

Poly. (E(avge,ρ=.5))

Poly. (E(min, ρ=.2))



Uniformity at the Working Plane vs. Partition Ht. above Working Plane

0

0.1

0.2

0.3

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0.5

0.6

0.7

0.8

0.9

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7


Wor

kpla

ne U

nifo

rmity

U(min/avge,ρ=.2)

U(min/avge,ρ=.5)

Poly. (U(min/avge,ρ=.2))



○ Partition height has a significant effect on average illuminance ● Significant impact on minimum value

○ Partition reflectance also affects the result, but to a much lesser extent ● Indirect flux component.

○ Location of minimum values no longer on the perimeter.

○ User-defined lighting (or other) to correct this

Design Change – Partition Arrangement


Average Illuminance at the Working Plane vs. Partition Ht. above Working Plane (diagonal arrangement)

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100

150

200

250

300

350

400

450

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7


Wor

kpla

ne A

vera

ge Il

lum

inan

ce

E(avge, ρ=.2)

E(avge,ρ=.5)

E(min, ρ=.2)

E(min, ρ=.5)

Poly. (E(avge, ρ=.2))

Poly. (E(avge,ρ=.5))




Uniformity at the Working Plane vs. Partition Ht. above Working Plane (diagonal arrangement)

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7


Wor

kpla

ne U

nifo

rmity

U(min/avge,ρ=.2)

U(min/avge,ρ=.5)




○ The difference between partition orientations is minimal.

Design Change - Floor Finish

○ Inappropriate selection can lead to premature wear, more obvious staining through use, slip hazard or glare

○ Floor surface types vary widely ● Carpet, timber veneer, ultra-modern epoxy finishes.

○ Whilst other room surfaces, (walls, ceilings) degrade over time, flooring degrades faster, given the constant, direct and harsh use this surface is subject to.


Average Illuminance vs. Floor Reflection (with Walls ρ=0.5, Desks ρ=0.5 Partitions 1.2m ρ=0.2)

335

340

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370

375

0% 10% 20% 30% 40% 50% 60%

Floor Reflectance

Ave

rage

Wor

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ce

E(avge)Poly. (E(avge))


Uniformity vs. Floor Reflection (with Walls ρ=0.5, Desks ρ=0.5 Partitions 1.2m ρ=0.2)

0.13

0.14

0.15

0.16

0.17

0% 10% 20% 30% 40% 50% 60%

Floor Reflectance

Wor

king

Pla

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nifo

rmity



○ Increasing reflectance by 50%: ● E(avge) = 2% ● Ρ = +7%

○ Minimum impact on these 2 key performance criteria

Conclusions

○ Design changes affecting indirect component have a smaller impact on Average Illuminance and Uniformity ● (paint and surface finishes)

○ Compound effect of multiple changes can represent a substantial change overall.

○ Design changes affecting direct component have a greater impact on Average Illuminance and Uniformity ● Partitions and other vertical obstructions

Design Guide

○ Make the information generic ● Factor the changes

○ Establish base performance ● What assumptions were made:

• Did the lighting design consider the inclusion of any furniture/partitioning in the space?

• What was the assumed Ceiling reflectance? • What was the assumed Wall reflectance? • What was the assumed Floor reflectance? • What was the assumed Maintenance Factor?

Design Guide

○ Assess the Interior Design Changes ● Apply factors to the base performance (Illuminance

and Uniformity)

○ Determine if further input is required from Lighting Designer ● Redesign lighting scheme ● Input on other options for task lighting improvements

• User-defined task lighting • Daylight Integration

Design Guide

Working Plane Illuminance and Uniformity Variance for Wall Colour Changes

Surface Reflectances E(avge) U(min/avge)

Ceiling Colour/ Reflectance No Change Wall Colour/

Reflectance

0%

Floor Colour/ Material

No Change

0.94 0.95

14% 0.95 0.95

40% 0.96 0.98

70% 0.98 0.99

100% 1.00 1.00

124% 1.02 1.01

148% 1.04 1.01

168% 1.06 1.02

184% 1.07 1.01

198% 1.09 1.01

○ Example of Table for Wall Reflectance changes

Design Guide

○ Educate Interior Designers ○ Provide guidelines for them to involve Lighting

Designers further, or curtail design modifications within acceptable limits (for lighting performance)

○ Promotes thought on lighting issues