Lighting for the Workplace

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CONTENTS

Foreword by Paul Morrell,

4–5

President of the British Council for Offices 6–7

INTRODUCTION

The Changing Corporate Perspective

6–7

WORKPLACE LIGHTING – PAST, PRESENT AND FUTURE

Lighting Research versus the Codes

10–11

– The Lessons of Lighting Research

12–15

– Current Guidance and its Limitations

16–23

Key Issues in Workplace Lighting

24–29

Natural Light, Active Light & Balanced Light

30–37

Further Considerations in Workplace Lighting

38–47

Lighting Techniques – Comparing the Options

48–51

W O R K P L A C E L I G H T I N G – A P P L I C AT I O N A R E A S

Open Plan Offices

56–67

Cellular Offices

68–71

Dealer Rooms

72–75

Control Rooms

76–79

Call Centres

80–83

Communication Areas/Meeting Rooms

84–87

Break-Out Zones

88–91

Storage

92–93

Common Parts

94–97

IMPRINT Publisher: Zumtobel Staff GmbH, Dornbirn/A Design: Marketing Communication Reprints, even in part, require the permission of the publishers © 2005 Zumtobel Staff GmbH, Dornbirn/A

52–97

98–135

WORKPLACE LIGHTING – LIGHTING DESIGN

Product Selector

100–133

Advisory Services

134–135

References & Useful Websites

8–51

135

Paul Morrell President of the British Council for Offices (BCO)

London aims to continue being Europe’s leading financial centre and will need more, higher quality office space in the future (photo: Piper’s model of the future City of London, shown at MIPIM 2005)

FOREWORD

The UK office market, in particular in London, is changing, driven by a number of long-term trends in international banking and finance. Informed forecasts, such as the recent Radley Report *, point, firstly, to a shift towards our capital city, at the expense of Paris and Frankfurt, as Europe’s leading financial centre, with a commensurate pressure on office space. Secondly, we can see a medium-to-long term growth in the number of highly educated, mathematically literate graduates required to run these complex, sophisticated financial operations. This shift from low skill to high skill staff puts a premium Paul Morrell BSc FRICS Hon FRIBA President of British Council for Offices

on worker satisfaction, as they become ever more demanding of their company and working conditions. The lesson is clear – nothing is more important in a service economy like ours than the efficiency of the working environment.

In today’s fast-moving marketplace, successful companies must invest in improved design and specification, to attract and retain an increasingly valuable and demanding workforce. People, not technology, must become the driving force of future office design. If one looks at the ratio of long-term costs of any business, including building design, construction, maintenance and personnel, design is a tiny fraction of the total – about 0.05 % of the cost of your workers. Yet that very small investment in good design has been proven to have a huge impact on staff satisfaction, efficiency and profitability. To put it another way, if a building can increase the productivity of its occupants by 10 per cent, you essentially get it free.

For all these reasons, improved design and specification – and especially lighting, the subject of this timely brochure from Zumtobel Staff Lighting – can make a significant contribution to long-term success.

* The Outlook for Banks Operating in the City of London (Radley & Associates, March 2004)

5

People & The Workplace As Organisations change, so does the Role of the Workplace

Historical Perspective

H

um

Res an

ources Mana ge m

en

t

WORKFORCE “the wages grow exponentially”

Lower qualified Less Aspirational Resistant to Change Traditional division between Human Resources and Facilities Management

FM driven Desk/task area focus Functional

“a cost centre to be controlled”

WORKSTATION

Fa

Contemporary Best Practice

cil

r Co

ities

por

m manage

ate Managem

en

en

wellness war for talent gymnasia esprit de corps brand in the workplace very aspirational management culture attraction, retention, motivation

WORKFORCE Living at Work

WORKPLACE lifestyle in the workplace added value break out zones open change agenda common parts differentiation flexiworking best practice lighting

t

t

Productivity factors influenced by lighting: Speed Persistence Accuracy Attraction Retention Motivation Satisfaction Happiness Potential Untapped Lighting Dividend

The Untapped Lighting Dividend

Single Path – Physiological

Generic practice lighting (Louvred Downlights)

Best practice lighting (Direct/Indirect)

Visual Capabilities

Visual Capabilities

Task Performance

Conventional Productivity Result

Task Performance

"Lighting and task conditions that improve visibility lead to better task performance"

Enhanced Productivity Dividend

Dual Path – Physiological & Psychological Physiological Path Visual Capabilities

Personal Control Best practice lighting (Direct/Indirect and controls)

Task Performance

Task Performance

“People with dimming control showed more sustained motivation, and improved performance on a measure of attention”

Health & Wellbeing

“People with dimming control reported higher ratings of lighting quality, overall environmental satisfaction, and self-rated productivity”

Motivation

Personal Control

Appraisal Preference

“Lighting and task conditions that improve visibility lead to better task performance”

Health & Wellbeing

Mood Psychological Path*

“People who are more satisfied with their lighting, rate the space as more attractive, are happier, and more satisfied with their environment and their work”

Productivity factors influenced by lighting: Speed Persistence Accuracy Attraction Retention Motivation Satisfaction Happiness The Untapped Lighting Dividend

* ”This is the first time that this complete path has been demonstrated”

“Light is the key to well-being.” – Le Corbusier

lighting design should be based

workplaces – gymnasia, break-

cal, rather than purely visual,

on the latest scientific research

out zones, thoughtfully designed

aspects of lighting.

into lighting and visual comfort –

common parts.

most of which is ignored in

The leading financial houses in

Constructing and operating a

current advisory codes. As we

The advantages gained by such

the City of London and other

building can cost a lot of money

demonstrate on pages 12–15,

hygiene factors are only just

financial capitals have long

– but not nearly as much as the

this research points towards a

beginning to be fully appreciated

realised the importance of light-

cost of the people who occupy

number of significant conclu-

– easier change management,

ing – share dealer rooms, which

the building. In the same equa-

sions that are embodied in our

sense of belonging, mirroring

produce the most spectacular

tion the cost of the lighting is

whole approach to workplace

the employees own personal

profits, are always equipped

insignificant. Comparatively

lighting.

aspirations – being just some.

with state-of-the-art direct/indi-

So, far from being a cost to be

rect lighting systems. Most have

and better lighting can have a

These pages illustrate how good

controlled, the workplace is

sophisticated controls. Banks

huge, positive knock-on effect

lighting can pay dividends. The

increasingly being viewed as an

and share traders know that

for many years to come. Con-

historical management perspec-

asset to be managed. But all

such systems create the most

versely bad design can push up

tive of the workplace – a cost to

the investment in hygiene fac-

stimulating and visually comfort-

long-term costs – while hitting

be controlled – has lead to the

tors and company culture can

able working environments.

the bottom line.

adoption of a standardised, and

be stifled if we follow the con-

flawed, lighting approach for

ventional, flawed lighting design

However at Zumtobel Staff we

In a world where the pace of

offices. But there are signs of

path. As business management

don’t believe that the best light-

change in work patterns, com-

change. Exceptional businesses

changes so must lighting begin

ing should be confined only to

pany practices and technology

are beginning to incorporate a

to reap the untapped dividends

high profile bond traders and

is accelerating, we believe that

range of hygiene factors in their

associated with the psychologi-

the like – ordinary administrative

small investment in better design

staff and other grades should not have to compromise with inferior, direct downlighter sys-

Integrated Model of Lighting Quality*

d In

– “Lighting is for more than visibility” – “Comfort is more than glare control”

i

ual vid – – – – – –

We l l -

tems, which surveys show are

Be

in

universally disliked. For the sake

g

visibility activity social & communication mood, comfort health & safety aesthetic judgement

of job satisfaction, visual comfort and general well-being, they also deserve the best lighting – and that means direct/indirect systems. These central principles, derived from the findings of lighting science – direct/indi-

* Jennifer A. Veitch, Ph.D. National Research Council of Canada www.irc.nrc-cnrc.gc.ca/ie/light

rect lighting and dynamic, vari-

The Untapped Lighting Dividend – – – – –

installation maintenance operation energy environment

Eco

nomics

able light levels – lie at the core of this guide to office lighting. In combination they correspond to Zumtobel Staff’s central lighting – – – –

**

form composition style codes & standards

A rc h i t ecture

design philosophy, which can be summed up in the phrase “lighting for people”.

** see Chart page 7

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Economics

Extra for Best Practice Potential Untapped Lighting Dividend

Lighting Cost

7

Photo: Allan Kell/Intelligent Buildings 2004

T H E C H A N G I N G C O R P O R AT E P E R S P E C T I V E

M&E Fitout

Construction Costs

Shell & Core

Rent 15 Years

People Costs 15 Years

Business Operating Costs

“I’m not saying you can walk on light: it doesn’t have structure, but it is part of the structure of the thinking of the architecture.” Richard Meier

W O R K P L A C E L I G H T I N G – P A S T, P R E S E N T A N D F U T U R E

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Workplace Lighting – Architect: Foster & Partners

Past, Present and Future

Lighting Research versus the Codes

W O R K P L A C E L I G H T I N G – P A S T, P R E S E N T A N D F U T U R E

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Office lighting design is in-

Unfortunately our misguided

lighting is a much more signifi-

human sensitivity. It reaches

creasingly bound by a whole

codes have now come to pass

cant factor in workplace health

the depths of one’s heart and

raft of recommendations and

as good practice, because too

and efficiency than is generally

awakens something asleep

standards emanating from the

few skilled lighting designers

recognised – and should be left

there.”

UK and the EC. A minority of

get the opportunity to design

to the real lighting professionals.

– Motoko Ishii

these standards and recommen-

genuinely creative workplace

The best, healthiest and most

dations are useful – others, as

lighting – as opposed to the

effective lighting schemes result

we shall see, are either out-of-

reception area, the boardroom

from qualified, experienced

date, due to the fast-moving

or the presentation suite, where

designers thinking “outside the

nature of office technology, or

they are most often employed.

box” – basing their designs not

run contrary to the findings of

Developers don’t see good,

on outdated codes and recom-

the most recent lighting research

innovative office lighting as im-

mendations, but on the latest

in both Europe and the USA.

portant, preferring instead to

findings of lighting science.

Take the official codification of

allow non-lighting specialists to

“dark light” louvred downlights

design and install humdrum,

On pages 12–15 we summarise

in the 1980s, triggered by

and even harmful, lighting,

the conclusions of the most

increased VDT use in the work-

according to a crude distillation

important pieces of recent

place. As a result of that single

of the Codes – an approach we

research in the area of work-

recommendation, office lighting

sum up as “working inside the

place lighting. Then on pages

undoubtedly went downhil, as

box”. As the introduction to the

16–23 we analyse current office

we were plunged into a new

DIAL research (see page 13)

lighting standards and recom-

“Dark Age”. The main problem

pessimistically reports, “good

mendations, to see how they

was the Code’s concentration

lighting designs are rare”.

measure up to these research

“Light has a great influence on

findings.

on luminaire selection in isola-

In 1992 Royal Life Holdings opened their highly innovative new Headquarters in Peterborough in the UK, designed by Arup Associates. There was already recognition, re-inforced by the success of this building, that direct/indirect lighting provided a preferable airy, attractive workplace. Especially when considering the alternative gloom, so well illustrated here, of the lower height spaces alongside, fitted with the standard solution at the time – Category 2 downlighters.

tion, rather than considering the

At Zumtobel Staff we question

entire office environment in a

this approach. We would argue

holistic way.

that research indicates that

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The Lessons of Lighting Research

Light Right test site – In the most comprehensive study of its type researchers found overwhelming user preference for direct/indirect lighting systems.

1. Getting the Light Right The “Light Right” Consortium

In probably the most compre-

space as more attractive, are

To quote Ron Lewis, chairperson

hensive study of its type con-

happier, and are more com-

of the Light Right Consortium,

ducted in Albany, New York,

fortable and satisfied with their

“Lighting does matter. We have

researchers found that:

environment and work.”

sampled major US corporations

• “This is the first time that

and found a strong connection

is an independent authoritative research body in the USA, managed by the Pacific Northwest National Laboratory and

• Good lighting improves productivity* • 29–31 % of people under

supported by the Illuminating

downlight only systems rated

Engineering Society of North

them as uncomfortable

America, the International Asso-

• 91 % of people were comfort-

ciation of Lighting Designers,

able with a system of direct/

the International Facility Man-

indirect, wall washing and

agers Association, the US Department of Energy and the

dimming control • Dimming control over work-

US Environmental Protection

station lighting “increased

Agency, amongst others.

motivation” and allowed users to “sustain their persistence and vigilance over time”, and be “more accurate” • “People who are more satisfied with their lighting rate the

this complete path has been

between lighting, productivity

demonstrated”

and its overall value to businesses.” * The Light Right website (www.lightright.org) reproduces the research and results. Co-author of the Light Right research: J.A. Veitch. She is much respected for this and other work done with the Institute for Research in Construction, Ottawa.

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DIAL research test site showing two examples below where accent lighting materially improved user perception of the space, compared with the conventional scenarios above.

2. Accent on Interest

pictures and also onto desks, using spotlights or other point sources, were preferred over

DIAL, the German Institute of

all other scenarios. This finding

Applied Lighting, is an extremely

fits well with one of the central

reputable and influential re-

principles of Zumtobel Staff’s

search body, which also produ-

approach – that the best results

ces DIALUX, one of the leading

are obtained by a combination

lighting industry software pro-

of different types of luminaire,

grammes. In 1999 it carried out

which might include accent

research into user preferences

lighting (see Products and

for a number of office lighting

Resources).

scenarios, using a variety of luminaire types (see photos). Subjects’ assessments were made in terms of functionality, impression of brightness and the overall attractiveness of the space. One of the central findings was that office scenes which contained additional accent lighting, particularly onto

The Lessons of Lighting Research

The Fleischer research found that our preference for quantity and type of light varies according to task.

3. Dynamic Lighting for Stimulation Susanne Fleischer is a promi-

Fleischer found a clear relationship between lighting conditions outside and inside. People prefer warm direct lighting when the sky is overcast, and indirect cool lighting when sunny.

that “cool” colour temperature

Fleischer concludes: “… It is

lighting was more stimulating

possible to draw up variable

than “warm” colour tempera-

lighting situations … which pro-

tures.

vide an appropriate response

The final body of research with

to the requirements for type of

important implications for office

nent German researcher who

4. “Cool” Light for the “Third Eye”

until recently worked at the

The implication is that a static

activity, activation and well-

lighting has recently emerged

Institute for Hygiene and Occu-

lighting scene throughout the

being”. And again “It is therefore

from a number of research cen-

pational Physiology in Zurich.

day, is not the best way to moti-

possible to create lighting scena-

tres, including Brown University

She is the former head of the

vate and enhance performance.

rios for office applications which

in the USA. The main findings

“Lighting Harmony” research

More desirable is a lighting sys-

are ergonomically appropriate

are that, firstly, light does not

project, which has found that

tem that can vary not just the

and, moreover, which have a

simply affect the human body

people’s mood, motivation, per-

level, but also the ratio of

positive effect on people’s sub-

through our sense of vision. It

formance and feelings of satis-

uplight to downlight, as well as

jective well-being.”

appears that we also possess a

faction vary throughout the day,

varying the colour temperature.

so-called “third eye”, a unique

depending on interior and ex-

These functions are possible

non-visual photo-receptor cell in

terior light levels and their own

with Zumtobel Staff lighting

the retina directly linked to the

internal circadian rhythms. In

systems and are covered in

pineal gland, which in turn regu-

particular she found that people

our pages on Active Light and

lates our bodily cycles.

preferred direct lighting when

Balanced Light starting on

the sky was overcast and indi-

pages 34 and 35.

What is particularly interesting is

rect lighting when the sky was

that this cell is especially res-

clear and sunny. She also found

ponsive to certain types of light,

W O R K P L A C E L I G H T I N G – P A S T, P R E S E N T A N D F U T U R E

Research shows that the “third eye” receptor is far more responsive to light at the blue end of the spectrum as shown.

at the blue end of the spectrum

York suggests that 18 lux of

(410–460 nm). Exposure to

blue light is more effective at

blue, or “cool” blue-tinted light,

lowering melatonin levels than

seems to encourage the pineal

450 lux of white light.

Levels of attentiveness vary over a 24 hour cycle.

Where the Research Takes Us

• Should have forms of control that allow for varying light levels and distribution patterns

gland to suppress the produc-

The implications of this body

tion of melatonin (which makes

of research for office lighting

us sleep) and therefore impro-

design are clear:

ves alertness. And the light

• Offices should ideally have

doesn’t have to be very bright –

direct/indirect lighting systems

recent discoveries at the Light-

and wall washing

ing Research Centre in New

15

• Lighting should always be

according to time of day and outside conditions • A degree of local control is desirable • “Cool” colour temperature lamps are best for maintaining alertness and performance.

achieved with a mix of luminaires

visual pathway (images) photobiological pathway blue light (especially) suppresses melatonin

Current Guidance and its Limitations

Pentland International plc’s new North London headquarters – this 2003 British Council for Office’s Best of the Best Award winner features considerable lighting ingenuity. Architect: GHM Rock Townsend, Building Services: Fulcrum

Unfortunately, as we will see, most of the current codes

1. The BCO Fit-Out Guide

(CAT A) and Category B (CAT B) fit-outs for speculative office buildings – a distinction we

are either in conflict with one another – or don’t measure

The British Council for Offices

refer to throughout this publica-

up to the findings of current

is a hugely influential body that

tion. The box at right summaris-

research, being founded more

represents the main players in

es this distinction. Lighting is

on outdated prejudices and

office development. Its Fit-Out

included in the CAT A fit-out

half-understood ideas.

Guide*, which is regularly up-

provision, as part of “basic

dated in the light of new evi-

mechanical and electrical servi-

dence and changing market

ces”, despite the fact that it is

conditions, is written by people

impossible to know the final

who are both pragmatic and

users’ needs and furniture confi-

market-led. Due to the growing

guration at that stage. It is,

influence of the BCO, its guides

however, again mentioned

are rapidly pushing other

under CAT B as part of “Mecha-

Codes, such as those generat-

nical and electrical services

ed by CIBSE, to the margins.

tailoring and upgrades”.

CAT A and CAT B Fit-outs Explained A CAT A fit-out is the most basic fit-out (including floor coverings, ceilings, floors, M&E, WCs and most importantly, lighting) undertaken by the developer and/or letting agent to sell the space in a speculative development. It is based on an open-plan working scenario but is usually potentially sub-divisible, if necessary. As soon as a client has been found, he will take on the open-plan

One of the important distinctions the BCO makes in the latest Fit-Out Guide (October 2003) is between Category A

* The BCO also publish a Best Practice Guide, the 2005 edition to which Zumtobel Staff has contributed.

specification – or will commission a different fit-out.

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Wessex Water, near Bath, U.K. This building is one of very few ever to have achieved an “Excellent” rating under the BRE Environmental Assessment Method. Wessex Water was the first ever to achieve the highest possible rating of 10. Architect: Bennetts Associates, Building Services: Buro Happold

A CAT B fit-out is a bespoke fit-out commissioned if the client comes on board at an early stage – or after the CAT A fit-out has already been installed. It may include a new lighting scheme, blinds, partitions, IT systems, telephones, wall finishes etc. Often, but not always, the CAT A scheme, including the

In fact, as yet, lighting is not a

no added value in appointing

lighting schemes, to cope with

major priority for the BCO –

specialist lighting designers for

future change, with addressable

there is no specific mention of

the lighting fit-out of the areas

lighting controls and modular

lighting on the Contents page of

where most ordinary staff work

lighting systems. In its summary

the current Fit-Out Guide – it is

for most of the day. When they

of the different types of lighting

instead lumped in with “Building

do appoint them, they do so

system available, it does give

Services”, so advice is difficult

only for the specialist areas of

suspended, or freestanding,

to find. When you do find the

the shell-and-core, such as the

direct/indirect systems the high-

small section on lighting, the

entrance area and the atrium.

est recommendation.

mences with the following

For the rest the BCO Guide is

Daylight use and control is

important observation:

the only UK advisory document

briefly mentioned – and there is

that refers to VDT screen testing

an awareness of the issue of

message is mixed, but it com-

lighting, will be ripped out and everything re-specified from scratch. For obvious reasons, a CAT B fit-out will usually cost more than a CAT A scheme.

“Design guidance is no longer

and the recommendations of

glare. The Guide states “use of

prescriptive and allows consider-

EN29241-7 (see page 26). It

blinds … should be considered

able freedom for a suitably quali-

also proposes varied lighting

early on in the design process”.

fied and experienced designer

levels between 500 and 300 lux

Zumtobel Staff would take this

to produce certified, compliant

with provision for task lighting

further – in fact, on page 32 we

schemes of the quality required.”

for the visually impaired and

make a strong case for blinds

energy use targets for lighting in

being included as part of the

Unfortunately, as we have alrea-

CAT A fit-outs of 12 W/m2.

CAT A fit-out.

dy discussed, developers see

There is an emphasis on flexible

Current Guidance and its Limitations

Part L encourages the use of direct-indirect luminaires. Video Arts. Building Services: Downie Consulting

2. Building Regulations (Part L) for Commercial Buildings

The first thing to say is that the advent of Part L has made many professionals concentrate

The BRE “Ideal office” is their own signature office and makes full use of indirect-direct lighting, even being incorporated under the downstand areas. The wave-form ceiling provides a very even fall-off of ceiling luminance.

3. BRE Environmental Assessment Method (BREEAM)

exclusively on designing for

Credits are awarded against the criteria and an overall score rates the building as “Pass”, “Good”, “Very Good” and

The Building Regulations (Part L)

energy savings at the expense

For over a decade, the BRE’s

“Excellent”. On the BREEAM

for Commercial Buildings, 2001,

of other criteria. Lighting design

Environmental Assessment

for offices checklist, the salient

as applied to lighting, are the

driven solely by energy use is

Method (BREEAM) has been

criteria related to workplace

British government’s latest rather

not necessarily good design.

used to assess the environ-

lighting and visual conditions are

blunt instrument for cutting

For example a scheme using

mental performance of both

included in the section “Health

energy use in buildings, to com-

only direct downlighters may

new and existing buildings. It is

and Well-being”. Some of these

ply with the Kyoto agreement on

well comply with Part L, but it

regarded by the UK’s construc-

are already standard practice,

climate change. In summary, for

will not create visually comfor-

tion and property sectors as

but some are not so well known:

commercial buildings (with some

table working conditions for

the measure of best practice

minor exceptions) Part L speci-

people who work there. Good

in environmental design and

fies a maximum energy use of

lighting design is lighting desig-

management. The building

40 luminaire lumens per watt

ned for people, who in the long

types covered by BREEAM are

averaged across the entire buil-

term are much more important

offices, homes, industrial units

ding (and according to recent

than energy savings – but there

and retail units and the pro-

controlled system of glare

government statements, this

is no reason why good, visually

gramme’s main criteria concern

control (e.g. internal or exter-

may be increased by 25 % in

comfortable lighting designs

energy use and health and well-

the near future).

can’t easily comply with Part L.

being, amongst other things.

• At least 80 % of the net lettable floor area should be adequately daylit. • There should be an occupant-

nal blinds). • High frequency ballasts should be installed in office luminaires.

19

Photo: RT Rafn Sigur∂sson

W O R K P L A C E L I G H T I N G – P A S T, P R E S E N T A N D F U T U R E

This European installation would undoubtedly score “very good” or better under the BREEAM rating system.

• Maintained lighting levels

Under the Energy section, there

should be between 350–400 lux

is no specific reference to the

and the louvre design should

traditional measure of power

comply with the LG3 Adden-

usage (W/m2) nor to Part L’s term,

dum 2001.

Luminaire Lumens per Circuit

The LIGHT FIELDS suspended direct/indirect range incorporates the MPO (micro-pyramidal optic) to ensure glare-free lighting whilst having a very high LOR (up to 86 %).

• The provision of high frequency dimming ballasts as a minimum in perimeter zones. • Localised task area lighting instead of uniform lighting.

Watt. Rather, BREEAM predicts

• Mandatory daylight dimming

open-plan office spaces,

energy use and measures these

controls where the Daylight

where there is circulation

in CO2 emissions (see page 45).

• Control systems for lighting in

Factor exceeds 2 %. • Lighting systems that have

space and daylighting, should

gained high user preference in

be zoned into groups, with

BREEAM’s programme is an

any one lighting group cover-

important and worthy initiative

ing no more than four work-

in the push to improve our

places.

commercial building stock.

on louvre fittings, which

recent research surveys. • Amendment of the emphasis

However, if BREEAM is indeed

seems to mitigate against

a view outside (open air or

promoting Best Practice, it

other lighting solutions, such

atrium) with a maximum dis-

should incorporate the following

as direct/indirect systems,

tance of seven metres (approxi-

design measures in its checklist:

which the BRE has installed in

• All workstations should have

its own signature building! In

mately two office desk spaces) to the nearest window.

• The installation of blinds as

any case LG3 expressly exclu-

part of the Cat A fit out,

des compliance by luminaire

because they are expensive

selection only.

additions at the Cat B stage.

Building Services: Jones King

Current Guidance and its Limitations

The latest generation of MELLOW LIGHT (IV) showing excellent wall and ceiling luminance.

This Highly Commended installation was designed by Pinniger & Partners in 1993, predating the LG3 Addendum by 8 years. This is simply a Category 3 luminaire modified by a dropped defractor to put light on walls and ceilings.

4. SLL (CIBSE) Code for Lighting

5. SLL (CIBSE) Lighting Guide 3 (LG3) – The Visual Environment for Display Screen Use

The CIBSE SLL Code for Light-

rating system for luminaires and instead introduced a “Certificate of Conformity”, which addressed all the relevant issues, and required the room, not the lighting

ing is one of the best, most

equipment, to Comply with LG3.

comprehensive textbooks avail-

LG3 is probably the most used

able on the lighting of interiors.

document over the last decade

It includes not only detailed

in terms of lighting specification

While retaining some of the use-

schedules of illuminance for

for offices. The document com-

ful design tenets of the earlier

different types of space, it offers

prises an erudite dissertation on

LG3, including the need to put

a welter of good lighting design

the issues, problems and solu-

light onto walls and ceilings, the

advice, a survey of various

tions of lighting spaces for

Addendum adopted very odd

visual effects and an extensive

VDTs. The document has, how-

criteria for ceiling lighting – and

glossary of terms.

ever, been generally misapplied

missed an opportunity to up-

in that users ignored the objec-

date its advice on VDT screens:

tives of lighting the room but rather defaulted to compliance

A. The latest LG3 puts too

by luminaire selection only.

much emphasis on lighting the walls by prescribing a task/wall/

To counter this problem the SLL

ceiling illuminance ratio of

issued an Addendum in 2001

100/50/30. However, wall illumi-

that dropped the “Category”

nance really only has significance

W O R K P L A C E L I G H T I N G – P A S T, P R E S E N T A N D F U T U R E

Arup Associates own offices illustrate the benefit of direct-indirect lighting despite the low ceiling height.

With no view to the exterior this training centre is saved by the direct-indirect lighting solution.

for the visual appearance of

up to the ceiling?). And the best

As long ago as 1997 BS

cellular offices (where much of

way to ensure a bright ceiling is

EN 29241-7 (Ergonomic Requi-

the wall area is likely to be gl-

by using direct/indirect lighting

rements for Office Work with

azed in any case). In the vast

systems. Situations where a

Visual Display Terminals) recom-

majority of offices, which are

direct/indirect approach is not

mended screen testing, to dis-

open-plan, the walls are gene-

possible, due to low ceiling

cover the actual glare limits of

rally too far away to make much

heights, are discussed on page

individual types of screen, but

of a contribution to the visual

50–51.

LG3, written four years later,

scene.

21

does not recommend this course B. More importantly, LG3 is

of action – instead it has arbi-

We would argue that in terms of

still fixated on lighting for VDT

trarily chosen a fixed upper

the visual appearance of most

screens rather than people,

luminance limit on fittings of

office spaces, getting light onto

whereas recent advances in flat

1500 cd/m2. This figure was not

the ceiling is far more important

screen VDT technology threaten

chosen on the basis of any

as the large area of the ceiling

to make this issue a dead duck

genuine research and is already

dominates the peripheral vision.

within two years. Most modern

massively out-of-date, as the

However, ceiling brightness is a

positive (black on white) flat

real figures for different VDT

luminance issue, not a question

screen VDT terminals are not

screens in the Table on page 25

of illuminance (is LG3 compliance

susceptible to luminaire reflec-

show. Some modern screens

really going to be tested by

tions – but in any case they can

can now tolerate luminances

engineers standing on desks,

be easily tested to determine

above 5000 cd/m 2 without cau-

holding their illuminance meters

their actual susceptibility.

sing visual discomfort.

Current Guidance and its Limitations

To avoid gloom, increase the percentage of light on the ceiling far beyond the recommended levels.

6. SLL (CIBSE) Lighting Guide 7 (LG7) Office Lighting Guide

the illuminance ratio of the

Pillars and air-conditioning are two more considerations when designing “task area” lighting.

7. BS EN 12464-1

ceiling to the working plane

One major development embodied in BS EN 12464-1 is that

should be 20 % – another 10 %

BS EN 12464-1 has recently

the concept of “maintained illu-

lower than even LG3 and the

been published as a British

minance” and the UGR glare

The draft copy of this document

BCO Guide – which would

Standard in an endeavour to

index system have been intro-

is fairly extensive, but few people

de-prioritise the lighting of the

harmonise lighting standards in

duced to Europe for the first

will find the document of great

ceiling even further.

Europe – an effort that has

time, although the UK has been

interest. In fact it is unclear why

taken many years. EN 12464

familiar with these for years.

it has been produced at all,

does not give detailed design

EN 12464-1 also contains an

except as a fund-raising mea-

advice and in this regard the

extremely low (1000 Cd/m2) VDT

sure. LG7 has all the hallmarks

SLL Code for Lighting (see

luminance limit which is clearly

of being written by a committee

page 22) seems set to remain

nonsensical today, but probably

over an extensive period of time

the “bible” of applied interior

reflects the time the document

– for example, all the criteria

lighting.

took to prepare and produce.

relating to VDT lighting remain the same as LG3 Addendum 2001. However, there is no mention of EN 12464-1 or EN 29241 and most of the commentary is very basic and elementary. Most worryingly, it makes a recommendation, that

task height = 0.75 m

use

r flo

area

or-a

rea 1.00 m

W O R K P L A C E L I G H T I N G – P A S T, P R E S E N T A N D F U T U R E

23

Lighting for People: MELLOW LIGHT IV Balanced offers the opportunity to alter the colour temperature throughout the day in response to user preference.

BS EN 12464-1 strongly encourages designers to adopt “task

8. The Disability Discrimination Act

9. Conclusion

ced lighting research offer a

area” lighting (known in the UK as localised lighting) which is the While it is not possible to dispositioning of luminaires over, or cuss all the measures pertaining close to, the main working area.

to lighting and the interior en-

This is defined as the desk area, vironment embodied in this Act, plus the notional chair zone, as

we firmly believe that lighting

depicted in the diagram oppo-

that has been well designed,

site. It proposes lighting to

according to the approach spelt

500 lux within the task zone,

out in this brochure, should

reducing to 300 lux elsewhere.

meet all the necessary requirements. However, it should be

Localised lighting systems have

stressed that designers should

long been considered in the UK.

take cognisance of the Act,

Reduced power density and

and the needs of the visually

energy usage make them attrac-

impaired, when proposing a re-

tive but they do require the

duction in workplace light levels,

designers to know the space-

for energy-saving or other pur-

planning at early concept stage.

poses.

This is not likely in the speculative developer led UK market.

the findings of the most advan-

Many of the current lighting

more solid starting point for

codes and recommendations,

lighting excellence, than out-of-

most notably LG3, LG7 and

date codes and confused and

Part L, are way behind con-

contradictory recommendations.

temporary lighting research –

In the following Section, we out-

and on the whole, do not offer

line our distinctive approach to

effective guidance to produc-

some of the central issues.

ing quality lighting design for the workplace. Others, such as the BCO Fit-out Guide and the BREEAM proposals, are flawed but also have much to commend them. On the whole, Zumtobel Staff prefers to base its approach to lighting design on the principle of lighting for people and their visual comfort. We believe that

Key Issues in Workplace Lighting

W O R K P L A C E L I G H T I N G – P A S T, P R E S E N T A N D F U T U R E

When thinking about office light-

rather than within the confines

itself but in the patterns of

ing design, there are a number

of the orthodox, but misguided,

shadows, the light and the

of key issues that need to be

recommendations embodied in

darkness, that one thing

considered. In this section we

the codes, we will demonstrate

against another creates.”

look at these issues in the light

that more pleasant, visually

– Jun’ichiro Tanizaki, In Praise

of the most recent research out-

comfortable and stimulating

of Shadows

lined above – and put forward

office spaces can be created as

our considered design recom-

a result, while at the same time

mendations and solutions. By

achieving a Certificate of Con-

designing “outside the box”,

formity.

“We find beauty not in the thing

Blurred Image

Increasing tolerance to reflections Reducing tolerance to reflections

Sharp Image

Lmax (cd/m 2) positive

Type

Make and Model

Date of manufacture

Class

9500 4900 4400 3800 3700 3700 3500 3500 3200 3100 3000

CRT FPD FPD FPD FPD CRT FPD FPD FPD CRT FPD

LG Flatron 915 FT Plus Nokia 500Xa 15" FPD Compaq TFT 5005 15" FPD LG Flatron LCD 575 MS 15" FPD NEC Multisync LCD1760NX Samsung Syncmaster 700 IFT 17" CRT NEC Multisync 1810X Nokia Pro 800+ 18" FPD Dell Ultrashop 1504FP Ilyama LS902UT Visionmaster 1451 NEC 208UX+

Dec-02 Jun-99 Oct-00 Nov-00 Apr-03 Nov-99 Nov-01 Oct-99 Nov-02 Feb-02 Nov-03

I I I I I I I I I I I

2700 2500 2200 2000 2000 1900 1800 1700 1700

FPD FPD CRT FPD LAPTOP FPD FPD FPD FPD

Ilyama TXA 3813MT 15" FPD NEC 1980X Compaq 7500 PE1163T LG 560LS Toshiba Tecra 8000 LAPTOP Samsung Syncmaster 700 TFT 17" FPD LG Studioworks 500 LC 15" FPD LG 1510S Samsung 15" FPD

Not Known Jan-04 Feb-02 Jun-01 Jun-98 Not Known Feb-99 Aug-02 Not Known

I I I I I I I I I

1400 1400 1300 1200

FPD CRT CRT CRT

LG3:2001 B2.1 1500 cd/m2 limit LG Studioworks 880 LC 18" FPD Dell D828L 14" CRT Samsung Syncmaster 753s Samsung Syncmaster 550s 15" CRT

Dec-99 Dec-97 Oct-01 Not Known

I II I I

900

CRT

LG3:2001 B2.1 1000 cd/m2 limit AOC 4NLR 14" CRT

Jan-95

I

Please visit our website for further details: http://www.zumtobelstaff.co.uk/screentesting

“Standards and Regulations are out of step with Current

1. Taking the Screen Test Results

Research” – Bob Venning, Director of Arup The luminance limitations given in LG3 are not emphatically Lighting, LEN April 2004

Above is a table of actual measured data for many types of screen. The screens were originally tested following Lloyd, Mizukami, Boyce, A preliminary

derived and bear no resem-

model of lighting display interac-

blance to actual fact.

tion 1995 and more recently BS EN 29241-7. Ergonomic requirements for office work with visual display terminals.

25

Luminaire types with enhanced brightness

Brighter luminaires = Light, airy, upbeat environment Darker luminaires = Gloomy, oppressive downbeat environment

Typical “Cat 2” modular downlight

Key Issues in Workplace Lighting

Layout of Zumtobel Staff’s screen test laboratory.

1. Taking the Screen Test – Conclusion

office lighting scheme around mere supposition. So we offer a

Since time immemorial luminaires with a sidelight component (opal diffusers in this case) have contributed to the appearance of ceiling brightness.

2. Putting Light on the Ceiling

“Ceiling Brightness Impression” or CBI for short, which takes into account the visual bright-

service to all our clients to have As we have already demonstrat-

a sample VDT screen tested at

On previous pages we discussed

ness of the fittings themselves

ed, the correct procedure for

our state-of-the-art facility.

the importance of putting light

as contributors to the overall

on the ceiling, in terms of the

brightness of the ceiling.

VDT screens is not to set an

More recently ISO BS EN 13406:

overall visual brightness of the

Erroneously, this is something

arbitrary figure but actually to

2002 entitled Ergonomic requi-

space. This is best done with

that CIBSE and SLL have pre-

test them, as recommended in

rements for visual display units

direct/indirect luminaires, offering

cluded in LG3.

BS EN 29241-7 Ergonomic

based on flat panels has been

variable ratios of lighting distri-

Requirements for Office Work

introduced. BS EN 13406:2002

bution, which can be digitally

So let’s examine a user’s real

with Visual Display Terminals,

is based on the same basic prin-

controlled for different condi-

visual impression of two office

1997. Some of the latest results

ciples as BS EN 29241 but with

tions and times of day.

spaces. In this visual test, there

for modern screens are shown

additional measurements and cal-

in the table on page 25. In fact

culations required. These are

However, as we have already

equipped, firstly, with recessed

in the UK only Zumtobel Staff

included in the Zumtobel Staff

discussed, this is not always

louvre light fittings and, secondly,

currently undertakes screen

testing of such screens.

possible, due to low ceiling

with recessed dual component

heights or the requirement to

fittings, both seen from normal

determining the glare limits of

brightness tests, according

are two vistas of the same office

to the recommendations of

Contact our Technical Depart-

maintain an existing grid of

viewing angles. It is quite clear

BS EN 29241-7. We believe this

ment for more details.

recessed luminaires. Here we

that the ceiling in the second

is the correct course of action,

www.zumtobelstaff.co.uk/

recommend an alternative

installation appears considerably

rather than designing the entire

screentesting

design approach which we call

brighter, even though the illumi-

W O R K P L A C E L I G H T I N G – P A S T, P R E S E N T A N D F U T U R E

27

Dark louvred fittings give an impression of a dark ceiling while self-luminous luminaires quite evidently make the ceiling appear brighter.

nance of the ceiling surfaces is

To demonstrate further the

LIGHT or SYNTO, make a

Guide) “the creation of a com-

the same.

importance of CBI, Zumtobel

strong contribution to the CBI

fortable, stimulating visual en-

Staff has developed special

of a space, whereas non-self-

vironment by careful control of

The only conclusion is that the

software based on the repu-

luminous luminaires (such as

surface brightness and contrast

brightness of the luminaires

table, well-established CIE Glare

standard “dark light” louvres)

ratios”, how can CBI not be

themselves makes a real contri-

Algorithm, to enable accurate

have a negative effect on CBI.

taken into account?

bution to the ceiling’s overall

calculations to be made of the

In both cases the CBI effect

brightness, because the eye

exact additional brightness

must be taken into account,

For further information about

combines the different bright-

gained from the use of self-lumi-

because brightness contrasts

CBI or information on our CBI

ness contrasts within the field

nous, dual component fittings.

strongly influence the cognitive

calculation software, go to our

of view. This is the principle of

The results come in the form of

experience of a space and a

website:

the term Ceiling Brightness

a table of CBI values for lumi-

users’ appreciation of its visual

www.zumtobelstaff.co.uk/CBI

Impression (CBI). The use of

naires viewed both crosswise

quality.

self-luminous, dual component

and endwise, which can then be

fittings can be seen to have a

added to the existing percen-

There is no logic to CIBSE and

positive effect on how the en-

tage of task illuminance on the

SLL’s refusal to allow luminaire

vironment appears – and, at the

ceiling, to derive the total ceiling

brightness to be considered as

same time, dark, non-self-lumi-

brightness (see website for

an important, contributory factor

nous luminaires can have a

more details).

in the apparent brightness of the ceiling. If the overall objec-

negative effect on CBI. In conclusion, dual component

tive of any lighting design is (in

luminaires, such as MELLOW

the words of the BCO Fit-out

Key Issues in Workplace Lighting

AWB_Workplace_Q_Produktb_UK.qxd

03.05.2005

11:20 Uhr

Seite 29

W O R K P L A C E L I G H T I N G – P A S T, P R E S E N T A N D F U T U R E

29

We feel that the Declaration

3. Walls in the Cellular Office

4. Guaranteeing Conformity

The lighting of walls becomes a

The concept of the Declaration

good designers the freedom to

major issue in cellular offices,

of Conformity, to be signed by

work “outside the box”, to pro-

which tend to be the premium

designers at the end of a light-

duce creative, visually interest-

office spaces arranged around

ing project, to guarantee its

ing lighting schemes. In such

the perimeter of the building.

compliance with codes on ergo-

cases, only trained, experienced

Most often two of the four walls

nomics, health and energy use,

members of the CIBSE Society

will comprise windows and

was proposed in the latest LG3

of Light & Lighting (SLL), the

glazed interior partitions. The

document – probably in too

International Association of

window wall will require effec-

hurried a fashion, without suffi-

Lighting Designers (IALD) and

tive, light-coloured blinds for

cient consultation. As a result

the European Lighting Design-

solar control by day and to aid

take-up has been patchy, partly

ers’ Association (ELDA) should

the lit effect after dark, when

because it is not a legal obliga-

be given the responsibility for

they serve to reflect light back

tion and designers are worried

issuing a Declaration of Confor-

into the room, rather than the

about it affecting their professio-

mity to LG3 or Part L.

window appearing as an unlit

nal indemnity. The main drivers

dark hole.

of the Declaration of Conformity

of Conformity is a useful vehicle for allowing and encouraging

are Zumtobel Staff and the We would generally recommend

BCO, whose Fit-Out Guide calls

multi-component luminaires for

for the artificial lighting to be

such spaces to increase the

“provided with a Certificate of

degree of ceiling brightness –

Conformity to LG3 and Part L”.

these could be direct/indirect systems or dual component fittings (see page 50). Where downlighters are used, it is important to select one of the interior walls and make sure that it is well lit, through the use of additional perimeter wall

Society of Light and Lighting

International Association of Lighting Designers

washers.

Without windows, providing good illuminance on some walls makes all the difference.

LG3 2001: Certificate of Conformity

European Lighting Designers’ Association

Natural Light, Active Light & Balanced Light

W O R K P L A C E L I G H T I N G – P A S T, P R E S E N T A N D F U T U R E

“Surfaces define the shape of our world; light allows us to

1. Working with Daylight

see them.”

31

Diffuse daylight from an over-

during this process, of lighting

cast, but possibly still quite

quality. This is because lighting

bright, sky solves many of the

control system sellers are, in the

– George M Whiteside, On the

While artificial lighting has be-

problems associated with direc-

main, electrically biased, rather

Surface of Things

come increasingly sophisticated

tional sunlight. The light quality

than qualified in lighting. They

in recent years, it can’t compare

is generally diffuse with slow

tend to consider energy as the

with our greatest light source –

rates of change and reduced

number one, easily quantifiable

daylight. Daylight and sunlight is

contrasts.

target, while issues such as glare, contrast and the psychol-

free, unlimited, non-polluting and full of variety – and research

Despite the contribution daylight

ogy of the lit space, do not im-

shows that access to daylit

can make, modern artificial

pinge on their thinking. Zumtobel

views is seen as highly desirable

lighting is nearly always planned

Staff believes that simply dim-

by office users.

with the “worst case” scenario

ming down or switching off

in mind – i.e. that it is completely

artificial lighting, as daylight

So on visual comfort and energy-

dark outside. Many buildings

increases, is an over-simplified

saving grounds, any modern

employ conventional switching

approach – in fact, in many

workplace must recognise the

techniques which often mean

situations it may be desirable

presence and desirability of day-

that all the light fixtures remain

to increase the light output of

light – and should be designed

switched on, irrespective of the

artificial lighting as daylight

to make best use of it, in a fully

daylight state. More sophisti-

increases.

integrated manner.

cated buildings often employ various forms of photocell-based

However, natural daylight pro-

lighting control system, which

vides both a threat and an

are, on the whole, usually speci-

opportunity. Direct sunlight can

fied to achieve one purpose

create uncomfortable visual

alone – energy savings. This

conditions – excessive illumi-

usually means that as daylight

nance, discomfort and disability

increases, artificial lighting is

glare, screen reflections, and

dimmed; and when daylight

sometimes constant, rapid

reaches a sufficient level, it is

change – as well as thermal dis-

eventually switched off.

comfort. Brightness contrasts within a space can be consider-

While the energy savings accrued

able for people moving in and

by such a system are signifi-

out of a direct sunlit area.

cant, little account is taken

Natural Light, Active Light & Balanced Light

The highly sophisticated blinds used here turn conventional wisdom on its head. When fully open they allow an unrestricted exterior view but with possible glare issues. The compensation for this are the bright interior surfaces.

When the blinds are fully closed the view out is partially preserved and the glare threat eliminated. However, contrary to conventional thinking, ceiling illuminance is increased because the blinds are designed as “sun scoops”.

We also believe that the provi-

lit effect within the space.

provided in the basic Cat A fit-

sion of blinds should be part of

Without blinds, the windows

out for office developments (see

the fundamental lighting design

become “black holes” after

page 16–17). Instead, they tend

package for any building. While

dark, allowing a great deal of

to be provided as part of a Cat

blinds are conventionally seen

wasted light to exit the building.

B, tenant fit-out after the lighting design and installation has

as part of the architectural design, their relevance to lighting

Manually controlled blinds are

long been completed. A sub-

should not be under-estimated.

the norm but experience shows

standard, uncoordinated result

During the day properly desig-

that user positioning invariably

is almost inevitable.

ned, light coloured blinds can

leads to a chaotic and messy

be used to maximise the advan-

appearance. Electrically operat-

tages of daylight, while avoiding

ed, automatically controlled

the downside of glare – and

blinds are normally outside the

at the same time, they can pre-

scope of ordinary control sys-

serve important exterior views

tems that typically use internal,

from inside the building. Particu-

room photocells which cannot

larly in small cellular offices,

cope with sophisticated require-

they also have a vital role to

ments. The provision of blinds,

play at night, by acting as light

preferably properly automated

reflectors on one, or occasio-

and controlled, is a fundamental

nally, two window walls, which

factor in the visual comfort of an

has a huge influence on the

interior. Yet they are seldom

33

Slaughter & May, London

W O R K P L A C E L I G H T I N G – P A S T, P R E S E N T A N D F U T U R E

These 2 photographs are of the same office but inside and outside the perimeter zone. The areas are functionally similar but are fundamentally different in their access to daylight and therefore require different but complimentary lighting approaches.

2. Lighting for the Perimeter Zone

closer to the centre of the

sections here tend to be solid,

types for the daylight and deep

building may experience the en-

so precluding rows of recessed

plan zones. Either area could

vironment as gloomy and poorly

downlight troughs.

use Combination lighting or

Moving into the building away

lit, due to the contrast of their

from the windows, we come

space with the perimeter.

across the “transition zone” or “perimeter zone” between natu-

In this situation there is a strong

rally lit and wholly artificially lit

argument for different lighting

interiors. This often neglected

systems to be used in perimeter

area is critically important in

and deeper plan areas, to ease

determining the appearance,

the transition from daylight to

feel and balance of the entire

artificial light. However, the

space. For a start, the contribu-

standard solution has been to

tion of daylight can, depending

apply a uniform, regular array

on the window design, remain

across both these areas, ignor-

significant even considerable

ing that they are completely

distances into the space. For

different (except at night). Alter-

example, while high levels of

natively there is a strong ten-

daylight within the perimeter

dency to put circular recessed

areas tend to create bright,

downlights along the window

upbeat environments, those

wall, for no rational reason

workers who are positioned

other than the fact that ceiling

Balanced lighting, both of which Where possible, Zumtobel Staff

could also be Active Light sys-

advocates designing specific

tems.

and different lighting layouts and

Full height windows allow high levels of daylight but the extreme risk of glare makes blinds essential. The choice of blinds in this situation follows good practice – they are light in colour and preserve a view. The artificial lighting illuminates all surfaces providing a good balance of brightnesses.

Natural Light, Active Light & Balanced Light

These two scenes show how, by using the LA TRAVE direct/indirect lighting system, the lighting ambience can be changed dynamically across the day to suit different conditions.

The best Active Light systems

carefully designed lighting

allow:

scenarios, based on the kind of

Daylight changes constantly in

• Changing intensity of light

research outlined on pages

quantity, directional characteris-

• Changing direction of light

12–16, can both enhance and

tics and colour. The Active Light

• Changing colour of light

echo exterior illumination – and

concept, pioneered by Zumtobel

• Changing patterns of daylight

enhance people’s motivation

3. Active Light

Staff, is an attempt to introduce

through blind control

an element of change into artificial lighting in order to mimic

At the same time, by taking

the patterns of daylight. Surveys

into account our “circadian

show that people prefer the

rhythms”, which are determined

dynamic, constantly changing

by our biological clock and

character of natural lighting and

synchronised by daylight, it is

the objective of artificial lighting

possible to influence human

ought to come as close as pos-

physiology and psychology, and

sible to this ideal.

thus increase motivation and performance. From an ergonomic point of view, it is desirable that the working environment changes over the course of the day, in order to enhance the attention of staff. A series of

and willingness to perform.

W O R K P L A C E L I G H T I N G – P A S T, P R E S E N T A N D F U T U R E

A balanced light installation which also uses most of the principles of Active Light.

4. Balanced Light

Dimming the two light sources

35

A combination of recessed dual component luminaires and perimeter downlights. A new standard at Canary Wharf.

5. Combination Lighting

(or components within a single The most important aspect of

fitting) gives access to quantity

Combination Lighting is a rather

the Balanced Light concept

variations, while the separate,

simpler lighting set-up which

is that it offers variable Flux

selective control of the direct

involves two or more types of

Fraction Ratios (FFR), which is

and indirect lighting compo-

luminaire to achieve any lighting

to say the potential to vary the

nents can be used to alter

effect – for example a simple

upward and downward lighting

fundamentally the directional

downlight, combined with a peri-

components. This can be achie-

character of the light. Equipping

meter wallwasher. In its simplest

ved using a single luminaire,

the luminaires with mixed colour

form, Combination Lighting

such as the Zumtobel Staff La

temperature light sources also

could be just bulk switched

Trave fitting, equipped with sep-

allows fundamental colour tem-

on/off, or separately switched,

arately controllable lamps for

perature changes, making it

or dimmed – and the FFR

direct or indirect lighting. This

possible to balance the colour

needn’t necessarily change.

allows almost infinite variation in

characteristics of the lighting

the character of the lighting.

from warm and homely through

Alternatively, Balanced Lighting

to cool and businesslike.

might be achieved by a combination of two luminaire types, such as a downlight and a freestanding uplight.

LUXMATE EMOTION Workspace combines intuitive control and extremely professional use of DALI technology without actuators and dimmers; a specific ACTIVE LIGHT script based on scientific and ergonomic knowhow can be prepared for office lighting.

Natural Light, Active Light & Balanced Light

This novel “partial” blind system is automatically activated at night and at certain times of the day. The suspended LIGHTFIELD luminaires create very even lighting to the ceiling, walls and closed blinds.

6. Controls The BCO Fit-out Guide states

Here the blinds are lowered sufficiently to filter out glare at high angles but allow sunlight to penetrate at low levels, preserving the wonderful patterns and shadows of daylight.

can be easily “fooled”, since

Even Zumtobel Staff Basic day-

Any artificial lighting deserves

they measure a combination of

light systems use sensors which

the use of lighting controls, the

natural and artificial light.

are aimed out of a window

most sophisticated of which

in order to register accurate

offer control of individual lumi-

that lighting controls are a fundamental part of lighting design.

While changing light levels are

changes in natural lighting,

naires, or even the individual

The simplest controls provide

desirable, the illogical fluctuation

rather than measuring a mis-

lamps within those luminaires.

energy savings and flexibility

of illuminance resulting from

leading combination of daylight

The controls software should

but more sophisticated systems

poorly designed sensors is one

and artificial light.

permit a variety of scenes to be

can be used to integrate day-

of the main reasons why day-

light in a more genuine way.

light control systems are often

The Basic daylight module then

at any time. For Active Light

Measuring incoming daylight

sabotaged by users. By con-

allows three separate groups of

situations, specific Active Light

and adjusting artificial lighting

trast, Luxmate Professional*

luminaires to respond differently

software, which is easy-to-use

levels accordingly seems like a

daylight systems use a roof-

to daylight. So, for example,

yet highly sophisticated, is

simple method of integrating

mounted sensor which measur-

a row of perimeter luminaires

essential.

artificial and natural light. Yet

es the quantity of light, its

illuminating the wall sections

user acceptance of this simple

direction and overall sky bright-

between the windows, or the

technique can be very low

ness, in order to register accu-

window mullions, could be

unless lighting controls are

rate changes in the amount and

programmed to dim up as day-

carefully designed. Most sys-

quantity of daylight and adjust

light increases. This will reduce

tems employ ceiling-mounted

the lighting and blinds automati-

the contrast between wall and/

sensors, which measure inci-

cally.

or mullions and the windows

dent light in the room – but they

pre-programmed and called up

themselves.

* www.luxmate.co.uk

W O R K P L A C E L I G H T I N G – P A S T, P R E S E N T A N D F U T U R E

These two photos show how scene-setting controls can create a totally different ambience and lighting balance within a space.

7. Scene Setting

which infers there should be several luminaire types, each

The value of scene setting as

performing a different function.

a lighting control technique

In this way users can generate

has largely been lost in recent

their own “stage sets” to create

years. Over-complicated con-

different lighting moods within

trols, which force the end user

the space, for different activities.

to default to factory pre-sets,

Realistically, such scene settings

coupled with poor understand-

can only be orchestrated when

ing by controls professionals

the space planning and function

of lighting issues, means that

of the room is known, and the

balanced and easy-to-use

interplay of blind control for

scene-set systems are few and

daylight is integrated into the

far between.

various scenes.

Scene setting is often misunderstood as being the ability to preset several different lighting levels of one luminaire type in a given room. Its real value involves the ability to choose different lit effects in a room,

Scene setting can even be applied to circulatory areas.

37

Photo: RT Rafn Sigur∂sson

Further Considerations in Workplace Lighting

W O R K P L A C E L I G H T I N G – P A S T, P R E S E N T A N D F U T U R E

“More and more, so it seems to me, light is the beautifier of the

1. Lamp Brightness

The chart below demonstrates

from Zumtobel Staff include the

the current range of T16, T26

Aero fitting, with the Eldacon

and compact fluorescent lamps

Panel which uses a technique of

It is an unfortunate fact that as

with their recommended bright-

“distributed” lamp image, and the

modern lamp sources get small-

ness threshold zones. If these

Mellowlight range, where the lamp

er and more efficient, their sur-

lamps are used in open fixtures,

is diffused by a Gridmesh optic.

face brightness increases – this

one should always consider

Several other Zumtobel Staff pro-

can be a problem with open

some form of lamp obscuration.

ducts have refractor accessories

light fixtures in an office, where

In general the brightness of

that can be added to mitigate the

a small, but very bright light

High Efficiency (HE) T16 flu-

problem of using HE T16 lamps.

source can create visual distrac-

orescent lamps at 15,000–

tion in the field of view. Even in

17,000 cd/m 2 are within tolera-

For this reason we would unequi-

luminaires with vertical louvres,

ble limits for direct viewing – but

vocally recommend specifying an

which reduce the sideways visi-

High Output (HO) lamps at

HE lamp, rather than its HO equi-

bility of the lamp, the view

between 25,000–32,000 cd/m2

valent, in any luminaire offering a

directly upwards into the fitting

exceed these limits, while TC-L,

direct view of an unshielded lamp

can be visually uncomfortable

TC-D and TC-T lamps are even

from any position in the work-

and can often be peripherally

brighter, at 30,000 cd/m2 up

place. In 600 mm modular lumi-

glimpsed as a distracting area

to a massive 70,000 cd/m ,

naires this is always an option. In

of brightness – what has been

depending on wattage.

addition, there are energy saving

building.” – Frank Lloyd Wright

2

dubbed “eyebrow glare”. This

benefits – as their name suggests,

issue of lamp brightness is

Of course, many of the latest

HE lamps trade lower light output

much more significant in interior

luminaire concepts have human

for higher energy efficiency (in

spaces, where people are

visual comfort as the highest

fact, energy efficiency is about

working over a full working day,

priority – and therefore have

15 % greater for these lamps).

than in a circulation space or a

some form of integral lamp

However this is not always possi-

sales area.

obscuration device. Examples

ble – see page 41.

Luminance of Fluorescent Lamps

MPO technology incorporated into the LIGHTFIELDS range overcomes the lamp glare of even the latest light sources, with little effect on the LOR.

39

Further Considerations in Workplace Lighting

Optimum light output for T26 and T16 lamps is achieved at 25 °C and 35 °C respectively.

2. Lamp Operating Temperatures

of air handling luminaires – see 3. Air Handling Most contem-

Bypass air handling in the MELLOW LIGHT IV, with either TC-L or T16 lamp options, avoids any cooling of the lamp.

3. Air Handling with T16 and TC-L Lamps

porary office fittings are not only

mum air volumes for generic luminaire types are readily available.

Another important consideration

small in scale, commensurate

The issue of air return lumi-

in choosing lamps is the issue

with the T16 lamp itself, but

naires, still a popular option with

Please contact the Zumtobel

of operating temperature. In

their operating efficiencies are of

M&E consultants, is another

Staff Technical Office for

former times fluorescent lamps

significantly higher order than

important consideration.

advice

lost efficiency when used within

T26 or most TC-L lamp options.

enclosed luminaires – and lamp

Modern T16 lamps are designed

efficiency was improved by

for maximum efficiency at high

forced ventilation of the fitting,

temperature, so to draw chilled

for example by the return air

air across the lamps is likely to

from the air conditioning sys-

reduce operating efficiency by

tem. However T16 lamps are

as much as 25 %. Supply air can

designed to operate at higher

also be a problem when dischar-

temperatures and are therefore

ged in close proximity to a T16

most efficient within enclosed

luminaire. The diagram above

luminaires (see graph above).

shows a solution to the return

Most importantly, they cannot

air path that bypasses the lamp

be used in the return air stream

compartment altogether. Maxi-

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W O R K P L A C E L I G H T I N G – P A S T, P R E S E N T A N D F U T U R E

4. Ceilings and their Influence on Lamp Choice

If a designer is faced with such a ceiling grid, our advice is to change to 750 mm luminaire size which can either fit into a

In an ideal world, lighting which

750 mm square ceiling grid, or

incurs an ongoing revenue cost

into a 1500 mm square tartan

in a building, should dictate the

grid ceiling.

choice of ceiling. However for good reasons to do with lettable

The 750 mm square luminaire

space, there is a growing trend

uses 600 mm T16 lamps in a

for 500 mm as the base building

luminaire variant that has extend-

module, which gives 1500 mm

ed flanges as shown in the pic-

multiples for partition choice.

ture above.

A 500 mm square luminaire

A fully updated matrix of these

size is not a good choice with

various options is available from

respect to lamp choice, because

our Technical Department.

it narrows the options to TC-L and TC-D lamps which have the

Contact us on:

relative high brightness and are

[email protected]

less efficient than current best practice T16 lamps.

41

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Further Considerations in Workplace Lighting

2700 K

5. Colour in the Workplace The issues of colour and colour

6500 K

situation is now more compli-

(FFR), such as Zumtobel Staff’s

facilities, to help maintain sus-

cated as a result of three main

LA TRAVE fitting, are gaining

tained alertness.

shifts in technology and re-

greater acceptability. Here it is

search data:

possible to use a different

temperature in the modern

• Secondary Lamp Systems

(usually “cooler”) colour tem-

The latest version of the

workplace are increasingly

Firstly, premium offices will

perature lamp for the upward

acclaimed, and much-copied,

important to consider, as the

more often than not have a

component, and a “warmer”

MELLOW LIGHT system –

technologies for achieving

dimming facility, at least within

colour temperature for down-

MELLOW LIGHT IV – has the

such effects proliferate almost

the daylight zone. In the quest

ward focal glow (see page 35).

potential to incorporate sepa-

daily. Below we assess the

to match more closely the arti-

Thirdly, as explained on page

rate colour lamps, which can

most common techniques and

ficial lighting with daylight

15 there is much evidence

be used to create distinct

their associated problems and

within those zones, there is

from the so-called “third eye”

areas of colour, in addition to

opportunities.

now a wider acceptance of

research to support the use of

white light (above and below).

“cooler” colour temperatures.

extra high colour temperature

These might be used to add

Secondly suspended fixtures

lamps with a high blue con-

coloured highlights within an

with variable flux fraction ratio

tent, in 24-hour workplace

otherwise bland space.

• Lamp Colour Temperature The issue of lamp colour temperature is a perennial issue in office lighting design. In bygone days the usual choice

MELLOW LIGHT IV Balanced Surface-mounted luminaire

was a lamp with an “intermediate” colour temperature of around 4,000 K. However, the

Recessed luminaire

W O R K P L A C E L I G H T I N G – P A S T, P R E S E N T A N D F U T U R E

Balanced colour luminaires used in a refectory.

• Coloured Tints for Mood and

• Working with Self-Illuminat-

43

Colour changing: morning, noon and night

6. Discomfort Glare (UGR)

used where the “side view”,

Identity

ing Surfaces

While intense areas of satu-

ACTIVE LIGHT WALL systems

rated colour, which can be

or internally illuminated screens

Within the UK, the concept of

recommended glare limit for

visually distracting, are not

hiding RGB colour changers,

glare limits has been around

offices of UGR 19. If alternate

advisable for office spaces,

are the latest methods for

since 1961. However during the

luminaires are set endwise and

Zumtobel Staff does offer an

adding colour to vertical sur-

era of “low brightness” VDT

crosswise, very often the UGR

option for coloured additive

faces, such as walls. By using

louvre products, with very low

will be compliant.

tints inside some luminaires,

RGB colour mixing, a huge

UGRs, the subject was very

such as MELLOW LIGHT

palette of colours can be cre-

rarely addressed. Now with the

Please contact the Zumtobel

and PERLUCE. These can be

ated and distributed over even

growing prevalence of so-called

Staff Technical Office for more

used to add visual interest,

large surface areas. These can

“dual component” fixtures,

information.

to create distinctive moods

range from subtle pastels to

glare calculations are again

within the space – or to desig-

intense, saturated hues. The

necessary.

nate specific zones or work

use of intense coloured effects

functions, to aid team cohe-

could be most effective in pro-

The latest Dialux design soft-

sion and/or orientation in large

viding focus and impact in

ware offers a Glare calculation

buildings.

meeting spaces, break-out

module which is very useful.

zones or common parts. Or

One aspect of this programme

alternatively colour could be

is a new ability to calculate

used to mimic windows in day-

UGRs from an array of counter-

light-starved, deep-plan spaces.

rotated luminaires. This can be

which is the brightest aspect of the luminaire, exceeds the

Further Considerations in Workplace Lighting

CO2 EMISSIONS – a comparison 1 quantity 54 W T16 fluorescent lamp – 62.6 kg/annum* One large office building (1m sq. ft) – 1,000,000 kg/annum* One 747 return flight London to Singapore – 1,000,000 kg per return flight**

* “Calculated on the projected fuel mix for the grid 1998–2000. Actual figures may vary from the projections, but DEFRA (Department of the Environment, Food and Rural Affairs) plan to use a constant value until 2010.” ** See the UK’s 2002 National Atmospheric Emissions Inventory (NAEI) www.naei.org.uk for long haul flights

W O R K P L A C E L I G H T I N G – P A S T, P R E S E N T A N D F U T U R E

7. Energy

45

Watts per Square Metre per

relaxation of 20 % if the lumi-

The Kyoto Protocol, which be-

100 lux (W/m2/100 lux)

naires are “controlled”.

came legally binding in Feb. 2005, aims to curb and reduce the

The measurement of energy

We believe that this slightly

use is a crucial issue in today’s

more refined measure would be

Kgs of CO 2 per Square Metre

emission of greenhouse gases,

post-Kyoto world. However, the

a better yardstick to use, as it

Per Year (Kg/CO 2/m2/Year)

particularly CO2, in an attempt to

various methods and formulae

starts to take into consideration

BREEAM has its own measure,

control global warming. In

for measuring energy use in

the efficacy of the luminaire it-

Kg/CO 2/m2/Year, which predicts

Europe (inc.the UK) the govern-

relation to lighting are both

self. Using this measure:

true energy use in terms of the

ments are taking the expedient

production of carbon dioxide

option by imposing energy restric-

confusing and in some cases, incompatible. In this section we

• A figure of 2.5 W/m 2/100 lux

(CO2). There is no direct refe-

tions on buildings and a Climate

chart the variety of techniques

would be good practice for

rence to limits on lighting, but

Change Levy on businesses,

of assessing energy/power

uniform lighting.

credit points are awarded accord-

whilst avoiding the more difficult

ing to a scale of overall CO 2

issues of e.g. banning fuel hungry cars, or taxing aviation fuel.

loading in relation to lighting,

• A figure of 2.0 W/m2/100 lux

and unravel their advantages

for uniform lighting would be

production. A mid-range score

and disadvantages.

indicative of “high output” T16

would be 60 kg/CO2/m2/Year. It

lamps used in very efficient

is interesting to note that to

However important energy

Watts per Square Metre (W/m 2)

luminaires, with a high direct

achieve 500 lux at typical spac-

issues are, consideration for the

Historically, energy use has

component. These would

ing, a 54 W lamp would gener-

employees in the buildings

been erroneously measured via

actually result in poor visual

ate 10.9 kg/CO 2/m /Year – in

should take precedence. Fortu-

installed power loading, calcu-

conditions without some sup-

the UK a 54 W lamp burning for

nately visual quality need not be

lated in watts/m2. Unfortunately

plementary lighting.

2,500 hours produces around

compromised for the sake of

62.6 kg of CO 2 (some electricity

energy efficiency.

this crude method does not

• A figure below 2.0 W/m /100 lux 2

account for the efficiency of the

would be possible only with

luminaire or the length of time

localised and task lighting –

they are switched on. And pre-

this combination can easily

scribed targets vary enormously

achieve