Lighting Handbook Lighting for the Workplace

8/14/2019 Lighting Handbook Lighting for the Workplace

1/140

Lighting for theWorkplace


2/140


3/140

The Changing Corporate Perspective 67

Foreword by Paul Morrell, 45

President of the British Council for Offices

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

I N T R O D U C T I O N 67

Product Selector 100133

Advisory Services 134135

References & Useful Websites 135

W O R K P L A C E L I G H T I N G L I G H T I N G D E S I G N 98135

Lighting Research versus the Codes 1011 The Lessons of Lighting Research 1215

Current Guidance and its Limitations 1623

Key Issues in Workplace Lighting 2429

Natural Light, Active Light & Balanced Light 3037

Further Considerations in Workplace Lighting 3847

Lighting Techniques Comparing the Options 4851

WORKPLACE LIGHTING PAST, PRESENT AND FUTURE 851

Open Plan Offices 5667

Cellular Offices 6871

Dealer Rooms 7275

Control Rooms 7679

Call Centres 8083

Communication Areas/Meeting Rooms 8487

Break-Out Zones 8891

Storage 9293

Common Parts 9497

W O R K P L A C E L I G H T I N G A P P L I C A T I ON A R E A S 5297

C O N T E N T S 3


4/140

Paul MorrellPresident of the British Council for Offices (BCO)

London aims to continue being

Europes leading financial centre and

will need more, higher quality office

space in the future (photo: Pipers

model of the future City of London,

shown at MIPIM 2005)


5/140

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 Europes 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

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 todays 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 t o long-term

success.

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

F O R E W O R D 5

Paul Morrell BSc FRICS

Hon FRIBA President

of British Council for

Offices


6/140

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

Hum

anResourcesManagem

ent

Corp

orate Management

Facilitiesmanage

ment

HistoricalPerspective

Productivity factors

influenced by lighting:

Speed

Persistence

Accuracy

Attraction

Retention

Motivation

Satisfaction

Happiness

Potential Untapped Lighting

Dividend

ContemporaryBest Practice

WORKFORCE

the wages grow exponentially

WORKFORCELiving at Work

WORKPLACE

a cost centre to be controlled

WORKSTATION

Lower qualified

Less Aspirational

Resistant to Change

wellness

war for talent

gymnasia

esprit de corps

brand in the workplace

very aspirational

management culture

attraction, retention, motivation

lifestyle in the workplace

added value

break out zones

open change agenda

common parts

differentiation

flexiworking

best practice lighting

Traditional division between Human Resources and Facilities Management

FM driven

Desk/task area focus

Functional


7/140

The Untapped LightingDividend

Single Path Physiological

Dual Path Physiological & Psychological

Generic practicelighting

(Louvred Downlights)

VisualCapabilities

TaskPerformance

ConventionalProductivity

Result

Best practicelighting

(Direct/Indirect)

VisualCapabilities

TaskPerformance

"Lighting and taskconditions

that improve visibilitylead to better task

performance"

EnhancedProductivity

Dividend

VisualCapabilities

TaskPerformance

Lighting and taskconditions that improve

visibility lead to better taskperformance

Personal Control

Motivation

TaskPerformance

People with dimmingcontrol showed more

sustained motivation, andimproved performance on

a measure of attention

PersonalControl

Health &Wellbeing

People with dimming con-trol reported higher ratingsof lighting quality, overall

environmental satisfaction,and self-rated productivity

AppraisalPreference

Mood

Health &Wellbeing

People who are more sat-isfied with their lighting, ratethe space as more attrac-tive, are happier, and moresatisfied with their environ-

ment and their work

Best practicelighting

(Direct/Indirect andcontrols)

Physiological Path

Psychological Path**This is the first time that this com-

plete path has been demonstrated

Productivity factors

influenced by lighting:

Speed

Persistence

Accuracy

Attraction

Retention

Motivation

Satisfaction

Happiness

The Untapped

Lighting Dividend


8/140

Economics** Arch itectu

re

Indi

vidua

lWell-Being

The

Untapped

Lighting

Dividend

visibility

activity

social & communication

mood, comfort health & safety

aesthetic judgement

installation

maintenance

operation

energy

environment

form

composition

style

codes &

standards

workplaces gymnasia, break-

out zones, thoughtfully designed

common parts.

The advantages gained by such

hygiene factors are only just

beginning to be fully appreciated

easier change management,

sense of belonging, mirroring

the employees own personal

aspirations being just some.

So, far from being a cost to be

controlled, the workplace is

increasingly being viewed as an

asset to be managed. But all

the investment in hygiene fac-

tors and company culture can

be stifled if we follow the con-

ventional, flawed lighting design

path. As business management

changes so must lighting begin

to reap the untapped dividends

associated with the psychologi-

cal, rather than purely visual,

aspects of lighting.

The leading financial houses in

the City of London and other

financial capitals have long

realised the importance of light-

ing share dealer rooms, which

produce the most spectacular

profits, are always equipped

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

rect lighting systems. Most have

sophisticated controls. Banks

and share traders know that

such systems create the most

stimulating and visually comfort-

able working environments.

However at Zumtobel Staff we

dont believe that the best light-

ing should be confined only to

high profile bond traders and

the like ordinary administrative

staff and other grades should

not have to compromise with

inferior, direct downlighter sys-

tems, which surveys show are

universally disliked. For the sake

of job satisfaction, visual com-

fort and general well-being, they

also deserve the best lighting

and that means direct/indirect

systems. These central princi-

ples, derived from the findings

of lighting science direct/indi-

rect lighting and dynamic, vari-

able light levels lie at the core

of this guide to office lighting. In

combination they correspond to

Zumtobel Staffs central lighting

design philosophy, which can be

summed up in the phrase light-

ing for people.

Light is the key to well-being.

Le Corbusier

Constructing and operating a

building can cost a lot of money

but not nearly as much as the

cost of the people who occupy

he building. In the same equa-

ion the cost of the lighting is

nsignificant. Comparatively

small investment in better design

and better lighting can have a

huge, positive knock-on effect

or many years to come. Con-

versely bad design can push up

ong-term costs while hitting

he bottom line.

n a world where the pace of

change in work patterns, com-

pany practices and technology

s accelerating, we believe that

lighting design should be based

on the latest scientific research

into lighting and visual comfort

most of which is ignored in

current advisory codes. As we

demonstrate on pages 1215,

this research points towards a

number of significant conclu-

sions that are embodied in our

whole approach to workplace

lighting.

These pages illustrate how good

lighting can pay dividends. The

historical management perspec-

tive of the workplace a cost to

be controlled has lead to the

adoption of a standardised, and

flawed, lighting approach for

offices. But there are signs of

change. Exceptional businesses

are beginning to incorporate a

range of hygiene factors in their

Jennifer A. Veitch, Ph.D.

National Research Council of Canada

www.irc.nrc-cnrc.gc.ca/ie/light

ntegrated Model

of Lighting Quality*

Lighting is for more than

visibility

Comfort is more than glare

control

** see Chart page 7


9/140

T H E C H A N G I N G C O R P O R A T E P E R S P E C T I V E 7

Photo:Allan

Kell/IntelligentBuildings

2004

Economics

Potential

Untapped

Lighting

Dividend

Lighting Cost M&E Fitout Shell & Core Rent 15 Years People Costs 15 Years

Extra for BestPractice

Construction Costs Business Operating Costs


10/140

Im not saying you can

walk on light: it doesnt

have structure, but it is

part of the structure of

the thinking of the archi-

tecture.

Richard Meier


11/140

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 9

Past, Present and Future

Workplace Lighting

Architect:Foster&P

artners


12/140

Lighting Researchversus the Codes


13/140


Light has a great influence on

human sensitivity. It reaches

the depths of ones heart and

awakens something asleep

there.

Motoko Ishii

Office lighting design is in-

creasingly bound by a whole

raft of recommendations and

standards emanating from the

UK and the EC. A minority of

these standards and recommen-

dations are useful others, as

we shall see, are either out-of-

date, due to the fast-moving

nature of office technology, or

run contrary to the findings of

the most recent lighting research

in both Europe and the USA.

Take the official codification of

dark light louvred downlights

in the 1980s, triggered by

increased VDT use in the work-

place. As a result of that single

recommendation, office lighting

undoubtedly went downhil, as

we were plunged into a new

Dark Age. The main problem

was the Codes concentration

on luminaire selection in isola-

tion, rather than considering the

entire office environment in a

holistic way.

Unfortunately our misguided

codes have now come to pass

as good practice, because too

few skilled lighting designers

get the opportunity to design

genuinely creative workplace

lighting as opposed to the

reception area, the boardroom

or the presentation suite, where

they are most often employed.

Developers dont see good,

innovative office lighting as im-

portant, preferring instead to

allow non-lighting specialists to

design and install humdrum,

and even harmful, lighting,

according to a crude distillation

of the Codes an approach we

sum up as working inside the

box. As the introduction to the

DIAL research (see page 13)

pessimistically reports, good

lighting designs are rare.

At Zumtobel Staff we question

this approach. We would argue

that research indicates that

lighting is a much more signifi-

cant factor in workplace health

and efficiency than is generally

recognised and should be left

to the real lighting professionals.

The best, healthiest and most

effective lighting schemes result

from qualified, experienced

designers thinking outside the

box basing their designs not

on outdated codes and recom-

mendations, but on the latest

findings of lighting science.

On pages 1215 we summarise

the conclusions of the most

important pieces of recent

research in the area of work-

place lighting. Then on pages

1623 we analyse current office

lighting standards and recom-

mendations, to see how they

measure up to these research

findings.

In 1992 Royal Life Holdings opened

their highly innovative new Head-

quarters in Peterborough in the UK,

designed by Arup Associates. There

was already recognition, re-inforced

by the success of this building, thatdirect/indirect lighting provided a

preferable airy, attractive workplace.

Especially when considering the alter-

native gloom, so well illustrated here,

of the lower height spaces alongside,

fitted with the standard solution at

the time Category 2 downlighters.


14/140

1. Getting the

Light Right

The Light Right Consortium

is an independent authoritative

research body in the USA,

managed by the Pacific North-

west National Laboratory and

supported by the Illuminating

Engineering Society of North

America, the International Asso-

ciation of Lighting Designers,

the International Facility Man-

agers Association, the US

Department of Energy and the

US Environmental Protection

Agency, amongst others.

In probably the most compre-

hensive study of its type con-

ducted in Albany, New York,

researchers found that:

Good lighting improves pro-

ductivity*

2931 % of people under

downlight only systems rated

them as uncomfortable

91 % of people were comfort-

able with a system of direct/

indirect, wall washing and

dimming control

Dimming control over work-

station lighting increased

motivation and allowed users

to sustain their persistence

and vigilance over time, and

be more accurate

People who are more satis-

fied with their lighting rate the

space as more attractive, are

happier, and are more com-

fortable and satisfied with their

environment and work.

This is the first time that

this complete path has been

demonstrated

To quote Ron Lewis, chairperson

of the Light Right Consortium,

Lighting does matter. We have

sampled major US corporations

and found a strong connection

between lighting, productivity

and its overall value to busines-

ses.

* 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.

The Lessonsof Lighting Research

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


15/140

2. Accent

on Interest

DIAL, the German Institute of

Applied Lighting, is an extremely

reputable and influential re-

search body, which also produ-

ces DIALUX, one of the leading

lighting industry software pro-

grammes. In 1999 it carried out

research into user preferences

for a number of office lighting

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

pictures and also onto desks,

using spotlights or other point

sources, were preferred over

all other scenarios. This finding

fits well with one of the central

principles of Zumtobel Staffs

approach that the best results

are obtained by a combination

of different types of luminaire,

which might include accent

lighting (see Products and

Resources).

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

scenarios above.



16/140

The Lessonsof Lighting Research

4. Cool Light

for the Third Eye

The final body of research with

important implications for office

lighting has recently emerged

from a number of research cen-

tres, including Brown University

in the USA. The main findings

are that, firstly, light does not

simply affect the human body

through our sense of vision. It

appears that we also possess a

so-called third eye, a unique

non-visual photo-receptor cell in

the retina directly linked to the

pineal gland, which in turn regu-

lates our bodily cycles.

What is particularly interesting is

that this cell is especially res-

ponsive to certain types of light,

3. Dynamic Lighting

for Stimulation

Susanne Fleischer is a promi-

nent German researcher who

until recently worked at the

Institute for Hygiene and Occu-

pational Physiology in Zurich.

She is the former head of the

Lighting Harmony research

project, which has found that

peoples mood, motivation, per-

formance and feelings of satis-

faction vary throughout the day,

depending on interior and ex-

terior light levels and their own

internal circadian rhythms. In

particular she found that people

preferred direct lighting when

the sky was overcast and indi-

rect lighting when the sky was

clear and sunny. She also found

that cool colour temperature

lighting was more stimulating

than warm colour tempera-

tures.

The implication is that a static

lighting scene throughout the

day, is not the best way to moti-

vate and enhance performance.

More desirable is a lighting sys-

tem that can vary not just the

level, but also the ratio of

uplight to downlight, as well as

varying the colour temperature.

These functions are possible

with Zumtobel Staff lighting

systems and are covered in

our pages on Active Light and

Balanced Light starting on

pages 34 and 35.

Fleischer concludes: It is

possible to draw up variable

lighting situations which pro-

vide an appropriate response

to the requirements for type of

activity, activation and well-

being. And again It is therefore

possible to create lighting scena-

rios for office applications which

are ergonomically appropriate

and, moreover, which have a

positive effect on peoples sub-

jective well-being.

The Fleischer research found that our preference for quantity and type of light

varies according to task.

Fleischer found a clear relationship between lighting conditions outside and

inside. People prefer warm direct lighting when the sky is overcast, and in-

direct cool lighting when sunny.


17/140

visual pathway

(images)

photobiological

pathway

blue light (especially)suppresses melatonin

at the blue end of the spectrum

(410460 nm). Exposure to

blue, or cool blue-tinted light,

seems to encourage the pineal

gland to suppress the produc-

tion of melatonin (which makes

us sleep) and therefore impro-

ves alertness. And the light

doesnt have to be very bright

recent discoveries at the Light-

ing Research Centre in New

York suggests that 18 lux of

blue light is more effective at

lowering melatonin levels than

450 lux of white light.

Where the Research

Takes Us

The implications of this body

of research for office lighting

design are clear: Offices should ideally have

direct/indirect lighting systems

and wall washing

Lighting should always be

achieved with a mix of luminaires

Should have forms of control

that allow for varying light

levels and distribution patterns

according to time of day and

outside conditions

A degree of local control isdesirable

Cool colour temperature

lamps are best for maintaining

alertness and performance.

Research shows that the third eye receptor is far more responsive to light at

the blue end of the spectrum as shown.

Levels of attentiveness vary over a 24 hour cycle.



18/140

Current Guidanceand its Limitations

Unfortunately, as we will see,

most of the current codes

are either in conflict with one

another or dont measure

up to the findings of current

research, being founded more

on outdated prejudices and

half-understood ideas.

1. The BCO

Fit-Out Guide

The British Council for Offices

is a hugely influential body that

represents the main players in

office development. Its Fit-Out

Guide*, which is regularly up-

dated in the light of new evi-

dence and changing market

conditions, is written by people

who are both pragmatic and

market-led. Due to the growing

influence of the BCO, its guides

are rapidly pushing other

Codes, such as those generat-

ed by CIBSE, to the margins.

One of the important distinc-

tions the BCO makes in the

latest Fit-Out Guide (October

2003) is between Category A

(CAT A) and Category B (CAT B)

fit-outs for speculative office

buildings a distinction we

refer to throughout this publica-

tion. The box at right summaris-

es this distinction. Lighting is

included in the CAT A fit-out

provision, as part of basic

mechanical and electrical servi-

ces, despite the fact that it is

impossible to know the final

users needs and furniture confi-

guration at that stage. It is,

however, again mentioned

under CAT B as part of Mecha-

nical and electrical services

tailoring and upgrades.

* The BCO also publish a Best Practice

Guide, the 2005 edition to which

Zumtobel Staffhas contributed.

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 impor-

tantly, 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-di-

visible, if necessary. As soon

as a client has been found,

he will take on the open-planspecification or will com-

mission a different fit-out.

Pentland International plcs new North London headquarters this 2003 British Council for Offices Best of the Best Award winner features considerable lighting

ingenuity.Architect: GHM Rock Townsend, Building Services: Fulcrum


19/140

no added value in appointing

specialist lighting designers for

the lighting fit-out of the areas

where most ordinary staff work

for most of the day. When they

do appoint them, they do so

only for the specialist areas of

the shell-and-core, such as the

entrance area and the atrium.

For the rest the BCO Guide is

the only UK advisory document

that refers to VDT screen testing

and the recommendations of

EN29241-7 (see page 26). It

also proposes varied lighting

levels between 500 and 300 lux

with provision for task lighting

for the visually impaired and

energy use targets for lighting in

CAT A fit-outs of 12 W/m2.

There is an emphasis on flexible

lighting schemes, to cope with

future change, with addressable

lighting controls and modular

lighting systems. In its summary

of the different types of lighting

system available, it does give

suspended, or freestanding,

direct/indirect systems the high-

est recommendation.

Daylight use and control is

briefly mentioned and there is

an awareness of the issue of

glare. The Guide states use of

blinds should be considered

early on in the design process.

Zumtobel Staff would take this

further in fact, on page 32 we

make a strong case for blinds

being included as part of the

CAT A fit-out.

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 anew lighting scheme, blinds,

partitions, IT systems, tele-

phones, wall finishes etc.

Often, but not always, the

CAT A scheme, including the

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.

In fact, as yet, lighting is not a

major priority for the BCO

there is no specific mention of

lighting on the Contents page of

the current Fit-Out Guide it is

instead lumped in with Building

Services, so advice is difficult

to find. When you do find the

small section on lighting, the

message is mixed, but it com-

mences with the following

important observation:

Design guidance is no longer

prescriptive and allows consider-

able freedom for a suitably quali-

fied and experienced designer

to produce certified, compliant

schemes of the quality required.

Unfortunately, as we have alrea-

dy discussed, developers see

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



20/140


2. Building Regulations

(Part L)

for Commercial Buildings

The Building Regulations (Part L)

for Commercial Buildings, 2001,

as applied to lighting, are the

British governments latest rather

blunt instrument for cutting

energy use in buildings, to com-

ply with the Kyoto agreement on

climate change. In summary, for

commercial buildings (with some

minor exceptions) Part L speci-

fies a maximum energy use of

40 luminaire lumens per watt

averaged across the entire buil-

ding (and according to recent

government statements, this

may be increased by 25 % in

the near future).

The first thing to say is that the

advent of Part L has made

many professionals concentrate

exclusively on designing for

energy savings at the expense

of other criteria. Lighting design

driven solely by energy use is

not necessarily good design.

For example a scheme using

only direct downlighters may

well comply with Part L, but it

will not create visually comfor-

table working conditions for

people who work there. Good

lighting design is lighting desig-

ned for people, who in the long

term are much more important

than energy savings but there

is no reason why good, visually

comfortable lighting designs

cant easily comply with Part L.

3. BRE

Environmental Assessment

Method (BREEAM)

For over a decade, the BREs

Environmental Assessment

Method (BREEAM) has been

used to assess the environ-

mental performance of both

new and existing buildings. It is

regarded by the UKs construc-

tion and property sectors as

the measure of best practice

in environmental design and

management. The building

types covered by BREEAM are

offices, homes, industrial units

and retail units and the pro-

grammes main criteria concern

energy use and health and well-

being, amongst other things.

Credits are awarded against the

criteria and an overall score

rates the building as Pass,

Good, Very Good and

Excellent. On the BREEAM

for offices checklist, the salient

criteria related to workplace

lighting and visual conditions are

included in the section Health

and Well-being. Some of these

are already standard practice,

but some are not so well known:

At least 80 % of the net lett-

able floor area should be ade-

quately daylit.

There should be an occupant-

controlled system of glare

control (e.g. internal or exter-

nal blinds).

High frequency ballasts should

be installed in office luminaires.

Part L encourages the use of direct-indirect luminaires.

Video Arts. Building Services: Downie Consulting

The BRE Ideal office is their own signature office and makes full use of indi-

rect-direct lighting, even being incorporated under the downstand areas. The

wave-form ceiling provides a very even fall-off of ceiling luminance.


21/140

Maintained lighting levels

should be between 350400 lux

and the louvre design should

comply with the LG3 Adden-

dum 2001.

Control systems for lighting in

open-plan office spaces,

where there is circulation

space and daylighting, should

be zoned into groups, with

any one lighting group cover-

ing no more than four work-

places.

All workstations should have

a view outside (open air or

atrium) with a maximum dis-

tance of seven metres (approxi-

mately two office desk spaces)

to the nearest window.

Under the Energy section, there

is no specific reference to the

traditional measure of power

usage (W/m2) nor to Part Ls term,

Luminaire Lumens per Circuit

Watt. Rather, BREEAM predicts

energy use and measures these

in CO2 emissions (see page 45).

BREEAMs programme is an

important and worthy initiative

in the push to improve our

commercial building stock.

However, if BREEAM is indeed

promoting Best Practice, it

should incorporate the following

design measures in its checklist:

The installation of blinds as

part of the Cat A fit out,

because they are expensive

additions at the Cat B stage.

The provision of high frequency

dimming ballasts as a mini-

mum in perimeter zones.

Localised task area lighting

instead of uniform lighting.

Mandatory daylight dimming

controls where the Daylight

Factor exceeds 2 %.

Lighting systems that have

gained high user preference in

recent research surveys.

Amendment of the emphasis

on louvre fittings, which

seems to mitigate against

other lighting solutions, such

as direct/indirect systems,

which the BRE has installed in

its own signature building! In

any case LG3 expressly exclu-

des compliance by luminaire

selection only.


This European installation would undoubtedly score very good or better

under the BREEAM rating system.

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 %).

Photo:RT

Rafn

Sigursson


22/140


4. SLL (CIBSE)

Code for Lighting

The CIBSE SLL Code for Light-

ing is one of the best, most

comprehensive textbooks avail-

able on the lighting of interiors.

It includes not only detailed

schedules of illuminance for

different types of space, it offers

a welter of good lighting design

advice, a survey of various

visual effects and an extensive

glossary of terms.

5. SLL (CIBSE) Lighting

Guide 3 (LG3)

The Visual Environment for

Display Screen Use

LG3 is probably the most used

document over the last decade

in terms of lighting specification

for offices. The document com-

prises an erudite dissertation on

the issues, problems and solu-

tions of lighting spaces for

VDTs. The document has, how-

ever, been generally misapplied

in that users ignored the objec-

tives of lighting the room but

rather defaulted to compliance

by luminaire selection only.

To counter this problem the SLL

issued an Addendum in 2001

that dropped the Category

rating system for luminaires and

instead introduced a Certificate

of Conformity, which addressed

all the relevant issues, and requi-

red the room, not the lighting

equipment, to Comply with LG3.

While retaining some of the use-

ful design tenets of the earlier

LG3, including the need to put

light onto walls and ceilings, the

Addendum adopted very odd

criteria for ceiling lighting and

missed an opportunity to up-

date its advice on VDT screens:

A. The latest LG3 puts too

much emphasis on lighting the

walls by prescribing a task/wall/

ceiling illuminance ratio of

100/50/30. However, wall illumi-

nance really only has significance

This Highly Commended installation was designed by Pinniger & Partners in

1993, predating the LG3 Addendum by 8 years. This is simply a Category 3 lumi-

naire modified by a dropped defractor to put light on walls and ceilings.

The latest generation of MELLOW LIGHT (IV) showing excellent wall and ceil-

ing luminance.

BuildingServices:JonesKing


23/140

As long ago as 1997 BS

EN 29241-7 (Ergonomic Requi-

rements for Office Work with

Visual Display Terminals) recom-

mended screen testing, to dis-

cover the actual glare limits of

individual types of screen, but

LG3, written four years later,

does not recommend this course

of action instead it has arbi-

trarily chosen a fixed upper

luminance limit on fittings of

1500 cd/m2. This figure was not

chosen on the basis of any

genuine research and is already

massively out-of-date, as the

real figures for different VDT

screens in the Table on page 25

show. Some modern screens

can now tolerate luminances

above 5000 cd/m2 without cau-

sing visual discomfort.

for the visual appearance of

cellular offices (where much of

the wall area is likely to be gl-

azed in any case). In the vast

majority of offices, which are

open-plan, the walls are gene-

rally too far away to make much

of a contribution to the visual

scene.

We would argue that in terms of

the visual appearance of most

office spaces, getting light onto

the ceiling is far more important

as the large area of the ceiling

dominates the peripheral vision.

However, ceiling brightness is a

luminance issue, not a question

of illuminance (is LG3 compliance

really going to be tested by

engineers standing on desks,

holding their illuminance meters

up to the ceiling?). And the best

way to ensure a bright ceiling is

by using direct/indirect lighting

systems. Situations where a

direct/indirect approach is not

possible, due to low ceiling

heights, are discussed on page

5051.

B. More importantly, LG3 is

still fixated on lighting for VDT

screens rather than people,

whereas recent advances in flat

screen VDT technology threaten

to make this issue a dead duck

within two years. Most modern

positive (black on white) flat

screen VDT terminals are not

susceptible to luminaire reflec-

tions but in any case they can

be easily tested to determine

their actual susceptibility.


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

lighting solution.

Arup Associates own offices illustrate the benefit of direct-indirect lighting

despite the low ceiling height.


24/140


6. SLL (CIBSE) Lighting

Guide 7

(LG7) Office Lighting Guide

The draft copy of this document

is fairly extensive, but few people

will find the document of great

interest. In fact it is unclear why

it has been produced at all,

except as a fund-raising mea-

sure. LG7 has all the hallmarks

of being written by a committee

over an extensive period of time

for example, all the criteria

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 com-

mentary is very basic and ele-

mentary. Most worryingly, it

makes a recommendation, that

the illuminance ratio of the

ceiling to the working plane

should be 20 % another 10 %

lower than even LG3 and the

BCO Guide which would

de-prioritise the lighting of the

ceiling even further.

7. BS EN 12464-1

BS EN 12464-1 has recently

been published as a British

Standard in an endeavour to

harmonise lighting standards in

Europe an effort that has

taken many years. EN 12464

does not give detailed design

advice and in this regard the

SLL Code for Lighting (see

page 22) seems set to remain

the bible of applied interior

lighting.

One major development embo-

died in BS EN 12464-1 is that

the concept of maintained illu-

minance and the UGR glare

index system have been intro-

duced to Europe for the first

time, although the UK has been

familiar with these for years.

EN 12464-1 also contains an

extremely low (1000 Cd/m2) VDT

luminance limit which is clearly

nonsensical today, but probably

reflects the time the document

took to prepare and produce.

height =

0.75 m

taskarea

userfloor-area

1.00 m

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

recommended levels.

Pillars and air-conditioning are two more considerations when designing task

area lighting.


25/140

8. The Disability

Discrimination Act

While it is not possible to dis-

cuss all the measures pertaining

to lighting and the interior en-

vironment embodied in this Act,

we firmly believe that lighting

that has been well designed,

according to the approach spelt

out in this brochure, should

meet all the necessary require-

ments. However, it should be

stressed that designers should

take cognisance of the Act,

and the needs of the visually

impaired, when proposing a re-

duction in workplace light levels,

for energy-saving or other pur-

poses.

BS EN 12464-1 strongly encou-

rages designers to adopt task

area lighting (known in the UK

as localised lighting) which is the

positioning of luminaires over, or

close to, the main working area.

This is defined as the desk area,

plus the notional chair zone, as

depicted in the diagram oppo-

site. It proposes lighting to

500 lux within the task zone,

reducing to 300 lux elsewhere.

Localised lighting systems have

long been considered in the UK.

Reduced power density and

energy usage make them attrac-

tive but they do require the

designers to know the space-

planning at early concept stage.

This is not likely in the specula-

tive developer led UK market.

9. Conclusion

Many of the current lighting

codes and recommendations,

most notably LG3, LG7 and

Part L, are way behind con-temporary lighting research

and on the whole, do not offer

effective guidance to produc-

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 Staffprefers to base its approach to

lighting design on the principle

of lighting for people and their

visual comfort. We believe that

the findings of the most advan-

ced lighting research offer a

more solid starting point for

lighting excellence, than out-of-

date codes and confused and

contradictory recommendations.In the following Section, we out-

line our distinctive approach to

some of the central issues.


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


26/140

Key Issuesin Workplace Lighting


27/140

We find beauty not in the thing

itself but in the patterns of

shadows, the light and the

darkness, that one thing

against another creates.

Junichiro Tanizaki, In Praise

of Shadows

When thinking about office light-

ing design, there are a number

of key issues that need to be

considered. In this section we

look at these issues in the light

of the most recent research out-

lined above and put forward

our considered design recom-

mendations and solutions. By

designing outside the box,

rather than within the confines

of the orthodox, but misguided,

recommendations embodied in

the codes, we will demonstrate

that more pleasant, visually

comfortable and stimulating

office spaces can be created as

a result, while at the same time

achieving a Certificate of Con-

formity.

1. Taking the Screen

Test Results

The luminance limitations given

in LG3 are not emphatically

derived and bear no resem-

blance to actual fact.

Above is a table of actual mea-

sured data for many types of

screen. The screens were origi-

nally tested following Lloyd,

Mizukami, Boyce,A preliminary

model of lighting display interac-

tion 1995 and more recently BS

EN 29241-7. Ergonomic requi-

rements for office work with

visual display terminals.


Lmax (cd/m2)

positiveMake and Model Date of

manufactureClassType

9500 CRT LG Flatron 915 FT Plus Dec-02 I

4900 FPD Nokia 500Xa 15" FPD Jun-99 I

4400 FPD Compaq TFT 5005 15" FPD Oct-00 I

3800 FPD LG Flatron LCD 575 MS 15" FPD Nov-00 I

3700 FPD NEC Multisync LCD1760NX Apr-03 I

3700 CRT Samsung Syncmaster 700 IFT 17" CRT Nov-99 I

3500 FPD NEC Multisync 1810X Nov-01 I

3500 FPD Nokia Pro 800+ 18" FPD Oct-99 I

3200 FPD Dell Ultrashop 1504FP Nov-02 I

3100 CRT Ilyama LS902UT Visionmaster 1451 Feb-02 I3000 FPD NEC 208UX+ Nov-03 I

2700 FPD Ilyama TXA 3813MT 15" FPD Not Known I

2500 FPD NEC 1980X Jan-04 I

2200 CRT Compaq 7500 PE1163T Feb-02 I

2000 FPD LG 560LS Jun-01 I

2000 LAPTOP Toshiba Tecra 8000 LAPTOP Jun-98 I

1900 FPD Samsung Syncmaster 700 TFT 17" FPD Not Known I

1800 FPD LG Studioworks 500 LC 15" FPD Feb-99 I

1700 FPD LG 1510S Aug-02 I

1700 FPD Samsung 15" FPD Not Known I

LG3:2001 B2.1 1500 cd/m2 limit

1400 FPD LG Studioworks 880 LC 18" FPD Dec-99 I

1400 CRT Dell D828L 14" CRT Dec-97 II

1300 CRT Samsung Syncmaster 753s Oct-01 I

1200 CRT Samsung Syncmaster 550s 15" CRT Not Known I

LG3:2001 B2.1 1000 cd/m2 limit

900 CRT AOC 4NLR 14" CRT Jan-95 I

BlurredImage

Luminaire types withenhanced brightness

SharpImage

Typical Cat 2modular downlight

Reducing tolerance toreflections

Darker luminaires =Gloomy, oppressive

downbeat environment

Increasing tolerance toreflections

Brighter luminaires =Light, airy, upbeat

environment

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

Standards and Regulations

are out of step with Current

Research

Bob Venning, Director of Arup

Lighting, LEN April 2004


28/140

Key Issuesin Workplace Lighting

1. Taking the

Screen Test Conclusion

As we have already demonstrat-

ed, the correct procedure for

determining the glare limits of

VDT screens is not to set an

arbitrary figure but actually to

test them, as recommended in

BS EN 29241-7 Ergonomic

Requirements for Office Work

with Visual Display Terminals,

1997. Some of the latest results

for modern screens are shown

in the table on page 25. In fact

in the UK only Zumtobel Staff

currently undertakes screen

brightness tests, according

to the recommendations of

BS EN 29241-7. We believe this

is the correct course of action,

rather than designing the entire

office lighting scheme around

mere supposition. So we offer a

service to all our clients to have

a sample VDT screen tested at

our state-of-the-art facility.

More recently ISO BS EN 13406:

2002 entitled Ergonomic requi-

rements for visual display units

based on flat panels has been

introduced. BS EN 13406:2002

is based on the same basic prin-

ciples as BS EN 29241 but with

additional measurements and cal-

culations required. These are

included in the Zumtobel Staff

testing of such screens.

Contact our Technical Depart-

ment for more details.

www.zumtobelstaff.co.uk/

screentesting

Ceiling Brightness Impression

or CBI for short, which takes

into account the visual bright-

ness of the fittings themselves

as contributors to the overall

brightness of the ceiling.

Erroneously, this is something

that CIBSE and SLL have pre-

cluded in LG3.

So lets examine a users real

visual impression of two office

spaces. In this visual test, there

are two vistas of the same office

equipped, firstly, with recessed

louvre light fittings and, secondly,

with recessed dual component

fittings, both seen from normal

viewing angles. It is quite clear

that the ceiling in the second

installation appears considerably

brighter, even though the illumi-

2. Putting Light

on the Ceiling

On previous pages we discussed

the importance of putting light

on the ceiling, in terms of the

overall visual brightness of the

space. This is best done with

direct/indirect luminaires, offering

variable ratios of lighting distri-

bution, which can be digitally

controlled for different condi-

tions and times of day.

However, as we have already

discussed, this is not always

possible, due to low ceiling

heights or the requirement to

maintain an existing grid of

recessed luminaires. Here we

recommend an alternative

design approach which we call

Since time immemorial luminaires with a sidelight component (opal diffusers in

this case) have contributed to the appearance of ceiling brightness.

Layout of Zumtobel Staffs screen test laboratory.


29/140

nance of the ceiling surfaces is

the same.

The only conclusion is that the

brightness of the luminaires

themselves makes a real contri-

bution to the ceilings overall

brightness, because the eye

combines the different bright-

ness contrasts within the field

of view. This is the principle of

the term Ceiling Brightness

Impression (CBI). The use of

self-luminous, dual component

fittings can be seen to have a

positive effect on how the en-

vironment appears and, at the

same time, dark, non-self-lumi-

nous luminaires can have a

negative effect on CBI.

To demonstrate further the

importance of CBI, Zumtobel

Staff has developed special

software based on the repu-

table, well-established CIE Glare

Algorithm, to enable accurate

calculations to be made of the

exact additional brightness

gained from the use of self-lumi-

nous, dual component fittings.

The results come in the form of

a table of CBI values for lumi-

naires viewed both crosswise

and endwise, which can then be

added to the existing percen-

tage of task illuminance on the

ceiling, to derive the total ceiling

brightness (see website for

more details).

In conclusion, dual component

luminaires, such as MELLOW

LIGHT or SYNTO, make a

strong contribution to the CBI

of a space, whereas non-self-

luminous luminaires (such as

standard dark light louvres)

have a negative effect on CBI.

In both cases the CBI effect

must be taken into account,

because brightness contrasts

strongly influence the cognitive

experience of a space and a

users appreciation of its visual

quality.

There is no logic to CIBSE and

SLLs refusal to allow luminaire

brightness to be considered as

an important, contributory factor

in the apparent brightness of

the ceiling. If the overall objec-

tive of any lighting design is (in

the words of the BCO Fit-out

Guide) the creation of a com-

fortable, stimulating visual en-

vironment by careful control of

surface brightness and contrast

ratios, how can CBI not be

taken into account?

For further information about

CBI or information on our CBI

calculation software, go to our

website:

www.zumtobelstaff.co.uk/CBI


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


30/140

Key Issuesin WorkplaceLighting


31/140

3. Walls in the

Cellular Office

The lighting of walls becomes a

major issue in cellular offices,

which tend to be the premium

office spaces arranged around

the perimeter of the building.

Most often two of the four walls

will comprise windows and

glazed interior partitions. The

window wall will require effec-

tive, light-coloured blinds for

solar control by day and to aid

the lit effect after dark, when

they serve to reflect light back

into the room, rather than the

window appearing as an unlit

dark hole.

We would generally recommend

multi-component luminaires for

such spaces to increase the

degree of ceiling brightness

these could be direct/indirect

systems or dual component fit-

tings (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

washers.

4. Guaranteeing

Conformity

The concept of the Declaration

of Conformity, to be signed by

designers at the end of a light-

ing project, to guarantee its

compliance with codes on ergo-

nomics, health and energy use,

was proposed in the latest LG3

document probably in too

hurried a fashion, without suffi-

cient consultation. As a result

take-up has been patchy, partly

because it is not a legal obliga-

tion and designers are worried

about it affecting their professio-

nal indemnity. The main drivers

of the Declaration of Conformity

are Zumtobel Staff and the

BCO, whose Fit-Out Guide calls

for the artificial lighting to be

provided with a Certificate of

Conformity to LG3 and Part L.

We feel that the Declaration

of Conformity is a useful vehicle

for allowing and encouraging

good designers the freedom to

work outside the box, to pro-

duce creative, visually interest-

ing lighting schemes. In such

cases, only trained, experienced

members of the CIBSE Society

of Light & Lighting (SLL), the

International Association of

Lighting Designers (IALD) and

the European Lighting Design-

ers Association (ELDA) should

be given the responsibility for

issuing a Declaration of Confor-

mity to LG3 or Part L.

Without windows, providing

good illuminance on some

walls makes all the difference.


LG3 2001: Certificate of Conformity

Society of Light

and Lighting

International Association

of Lighting Designers

European Lighting

Designers Association


32/140

Natural Light, Active Light& Balanced Light


33/140

Surfaces define the shape of

our world; light allows us to

see them.

George M Whiteside, On the

Surface of Things

1. Working

with Daylight

While artificial lighting has be-

come increasingly sophisticated

in recent years, it cant compare

with our greatest light source

daylight. Daylight and sunlight is

free, unlimited, non-polluting

and full of variety and research

shows that access to daylit

views is seen as highly desirable

by office users.

So on visual comfort and energy-

saving grounds, any modern

workplace must recognise the

presence and desirability of day-

light and should be designed

to make best use of it, in a fully

integrated manner.

However, natural daylight pro-

vides both a threat and an

opportunity. Direct sunlight can

create uncomfortable visual

conditions excessive illumi-

nance, discomfort and disability

glare, screen reflections, and

sometimes constant, rapid

change as well as thermal dis-

comfort. Brightness contrasts

within a space can be consider-

able for people moving in and

out of a direct sunlit area.

Diffuse daylight from an over-

cast, but possibly still quite

bright, sky solves many of the

problems associated with direc-

tional sunlight. The light quality

is generally diffuse with slow

rates of change and reduced

contrasts.

Despite the contribution daylight

can make, modern artificial

lighting is nearly always planned

with the worst case scenario

in mind i.e. that it is completely

dark outside. Many buildings

employ conventional switching

techniques which often mean

that all the light fixtures remain

switched on, irrespective of the

daylight state. More sophisti-

cated buildings often employ

various forms of photocell-based

lighting control system, which

are, on the whole, usually speci-

fied to achieve one purpose

alone energy savings. This

usually means that as daylight

increases, artificial lighting is

dimmed; and when daylight

reaches a sufficient level, it is

eventually switched off.

While the energy savings accrued

by such a system are signifi-

cant, little account is taken

during this process, oflighting

quality. This is because lighting

control system sellers are, in the

main, electrically biased, rather

than qualified in lighting. They

tend to consider energy as the

number one, easily quantifiable

target, while issues such as

glare, contrast and the psychol-

ogy of the lit space, do not im-

pinge on their thinking. Zumtobel

Staff believes that simply dim-

ming down or switching off

artificial lighting, as daylight

increases, is an over-simplified

approach in fact, in many

situations it may be desirable

to increase the light output of

artificial lighting as daylight

increases.



34/140


We also believe that the provi-

sion of blinds should be part of

the fundamental lighting design

package for any building. While

blinds are conventionally seen

as part of the architectural de-

sign, their relevance to lighting

should not be under-estimated.

During the day properly desig-

ned, light coloured blinds can

be used to maximise the advan-

tages of daylight, while avoiding

the downside of glare and

at the same time, they can pre-

serve important exterior views

from inside the building. Particu-

larly in small cellular offices,

they also have a vital role to

play at night, by acting as light

reflectors on one, or occasio-

nally, two window walls, which

has a huge influence on the

lit effect within the space.

Without blinds, the windows

become black holes after

dark, allowing a great deal of

wasted light to exit the building.

Manually controlled blinds are

the norm but experience shows

that user positioning invariably

leads to a chaotic and messy

appearance. Electrically operat-

ed, automatically controlled

blinds are normally outside the

scope of ordinary control sys-

tems that typically use internal,

room photocells which cannot

cope with sophisticated require-

ments. The provision of blinds,

preferably properly automated

and controlled, is a fundamental

factor in the visual comfort of an

interior. Yet they are seldom

provided in the basic Cat A fit-

out for office developments (see

page 1617). Instead, they tend

to be provided as part of a Cat

B, tenant fit-out after the light-

ing design and installation has

long been completed. A sub-

standard, uncoordinated result

is almost inevitable.

The highly sophisticated blinds used here turn conventional wisdom on its

head. When fully open they allow an unrestricted exterior view but with possi-

ble 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 illu-

minance isincreased because the blinds are designed as sun scoops.


35/140

2. Lighting for the

Perimeter Zone

Moving into the building away

from the windows, we come

across the transition zone or

perimeter zone between natu-

rally lit and wholly artificially lit

interiors. This often neglected

area is critically important in

determining the appearance,

feel and balance of the entire

space. For a start, the contribu-

tion of daylight can, depending

on the window design, remain

significant even considerable

distances into the space. For

example, while high levels of

daylight within the perimeter

areas tend to create bright,

upbeat environments, those

workers who are positioned

closer to the centre of the

building may experience the en-

vironment as gloomy and poorly

lit, due to the contrast of their

space with the perimeter.

In this situation there is a strong

argument for different lighting

systems to be used in perimeter

and deeper plan areas, to ease

the transition from daylight to

artificial light. However, the

standard solution has been to

apply a uniform, regular array

across both these areas, ignor-

ing that they are completely

different (except at night). Alter-

natively there is a strong ten-

dency to put circular recessed

downlights along the window

wall, for no rational reason

other than the fact that ceiling

sections here tend to be solid,

so precluding rows of recessed

downlight troughs.

Where possible, Zumtobel Staff

advocates designing specific

and different lighting layouts and

types for the daylight and deep

plan zones. Either area could

use Combination lighting or

Balanced lighting, both of which

could also be Active Light sys-

tems.

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.

Full height windows

allow high levels of day-

light 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 bright-

nesses.


Slaughter&

May,

London


36/140


37/140

4. Balanced Light

The most important aspect of

the Balanced Light concept

is that it offers variable Flux

Fraction Ratios (FFR), which is

to say the potential to vary the

upward and downward lighting

components. This can be achie-

ved using a single luminaire,

such as the Zumtobel Staff La

Trave fitting, equipped with sep-

arately controllable lamps for

direct or indirect lighting. This

allows almost infinite variation in

the character of the lighting.

Alternatively, Balanced Lighting

might be achieved by a combi-

nation of two luminaire types,

such as a downlight and a free-

standing uplight.

Dimming the two light sources

(or components within a single

fitting) gives access to quantity

variations, while the separate,

selective control of the direct

and indirect lighting compo-

nents can be used to alter

fundamentally the directional

character of the light. Equipping

the luminaires with mixed colour

temperature light sources also

allows fundamental colour tem-

perature changes, making it

possible to balance the colour

characteristics of the lighting

from warm and homely through

to cool and businesslike.

5. Combination Lighting

Combination Lighting is a rather

simpler lighting set-up which

involves two or more types of

luminaire to achieve any lighting

effect for example a simple

downlight, combined with a peri-

meter wallwasher. In its simplest

form, Combination Lighting

could be just bulk switched

on/off, or separately switched,

or dimmed and the FFR

neednt necessarily change.

LUXMATE EMOTION Workspace

combines intuitive control and

extremely professional use of

DALI technology without actua-

tors and dimmers; a specific

ACTIVE LIGHT script based on

scientific and ergonomic know-

how can be prepared for office

lighting.

A balanced light installation which also uses most of the principles of

Active Light.

A combination of recessed dual component luminaires and perimeter down-

lights. A new standard at Canary Wharf.



38/140


6. Controls

The BCO Fit-out Guide states

that lighting controls are a fun-

damental part of lighting design.

The simplest controls provide

energy savings and flexibility

but more sophisticated systems

can be used to integrate day-

light in a more genuine way.

Measuring incoming daylight

and adjusting artificial lighting

levels accordingly seems like a

simple method of integrating

artificial and natural light. Yet

user acceptance of this simple

technique can be very low

unless lighting controls are

carefully designed. Most sys-

tems employ ceiling-mounted

sensors, which measure inci-

dent light in the room but they

can be easily fooled, since

they measure a combination of

natural and artificial light.

While changing light levels are

desirable, the illogical fluctuation

of illuminance resulting from

poorly designed sensors is one

of the main reasons why day-

light control systems are often

sabotaged by users. By con-

trast, Luxmate Professional*

daylight systems use a roof-

mounted sensor which measur-

es the quantity of light, its

direction and overall sky bright-

ness, in order to register accu-

rate changes in the amount and

quantity of daylight and adjust

the lighting and blinds automati-

cally.

Even Zumtobel Staff Basic day-

light systems use sensors which

are aimed out of a window

in order to register accurate

changes in natural lighting,

rather than measuring a mis-

leading combination of daylight

and artificial light.

The Basic daylight module then

allows three separate groups of

luminaires to respond differently

to daylight. So, for example,

a row of perimeter luminaires

illuminating the wall sections

between the windows, or the

window mullions, could be

programmed to dim up as day-

light increases. This will reduce

the contrast between wall and/

or mullions and the windows

themselves.

Any artificial lighting deserves

the use of lighting controls, the

most sophisticated of which

offer control of individual lumi-

naires, or even the individual

lamps within those luminaires.

The controls software should

permit a variety of scenes to be

pre-programmed and called up

at any time. For Active Light

situations, specific Active Light

software, which is easy-to-use

yet highly sophisticated, is

essential.

* www.luxmate.co.uk

This novel partial blind system is automatically activated at night and at cer-

tain times of the day. The suspended LIGHTFIELD luminaires create very even

lighting to the ceiling, walls and closed blinds.

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.


39/140

7. Scene Setting

The value of scene setting as

a lighting control technique

has largely been lost in recent

years. Over-complicated con-

trols, which force the end user

to default to factory pre-sets,

coupled with poor understand-

ing by controls professionals

of lighting issues, means that

balanced and easy-to-use

scene-set systems are few and

far between.

Scene setting is often misunder-

stood 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,

which infers there should be

several luminaire types, each

performing a different function.

In this way users can generate

their own stage sets to create

different lighting moods within

the space, for different activities.

Realistically, such scene settings

can only be orchestrated when

the space planning and function

of the room is known, and the

interplay of blind control for

daylight is integrated into the

various scenes.

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


Scene setting can even

be applied to circulatory

areas.


40/140

Further Considerationsin Workplace Lighting

Photo:RT

RafnS

igursson


41/140

More and more, so it seems to

me, light is the beautifier of the

building.

Frank Lloyd Wright

1. Lamp

Brightness

It is an unfortunate fact that as

modern lamp sources get small-

er and more efficient, their sur-

face brightness increases this

can be a problem with open

light fixtures in an office, where

a small, but very bright light

source can create visual distrac-

tion in the field of view. Even in

luminaires with vertical louvres,

which reduce the sideways visi-

bility of the lamp, the view

directly upwards into the fitting

can be visually uncomfortable

and can often be peripherally

glimpsed as a distracting area

of brightness what has been

dubbed eyebrow glare. This

issue of lamp brightness is

much more significant in interior

spaces, where people are

working over a full working day,

than in a circulation space or a

sales area.

The chart below demonstrates

the current range of T16, T26

and compact fluorescent lamps

with their recommended bright-

ness threshold zones. If these

lamps are used in open fixtures,

one should always consider

some form of lamp obscuration.

In general the brightness of

High Efficiency (HE) T16 flu-

orescent lamps at 15,000

17,000 cd/m2 are within tolera-

ble limits for direct viewing but

High Output (HO) lamps at

between 25,00032,000 cd/m2

exceed these limits, while TC-L,

TC-D and TC-T lamps are even

brighter, at 30,000 cd/m2 up

to a massive 70,000 cd/m2,

depending on wattage.

Of course, many of the latest

luminaire concepts have human

visual comfort as the highest

priority and therefore have

some form of integral lamp

obscuration device. Examples


from Zumtobel Staff include the

Aero fitting, with the Eldacon

Panel which uses a technique of

distributed lamp image, and the

Mellowlight range, where the lamp

is diffused by a Gridmesh optic.

Several other Zumtobel Staff pro-

ducts have refractor accessories

that can be added to mitigate the

problem of using HE T16 lamps.

For this reason we would unequi-

vocally recommend specifying an

HE lamp, rather than its HO equi-

valent, in any luminaire offering a

direct view of an unshielded lamp

from any position in the work-

place. In 600 mm modular lumi-

naires this is always an option. In

addition, there are energy saving

benefits as their name suggests,

HE lamps trade lower light output

for higher energy efficiency (in

fact, energy efficiency is about

15 % greater for these lamps).

However this is not always possi-

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.


42/140


2. Lamp Operating

Temperatures

Another important consideration

in choosing lamps is the issue

of operating temperature. In

former times fluorescent lamps

lost efficiency when used within

enclosed luminaires and lamp

efficiency was improved by

forced ventilation of the fitting,

for example by the return air

from the air conditioning sys-

tem. However T16 lamps are

designed to operate at higher

temperatures and are therefore

most efficient within enclosed

luminaires (see graph above).

Most importantly, they cannot

be used in the return air stream

of air handling luminaires see

3. Air Handling Most contem-

porary office fittings are not only

small in scale, commensurate

with the T16 lamp itself, but

their operating efficiencies are of

significantly higher order than

T26 or most TC-L lamp options.

3. Air Handling with

T16 and TC-L Lamps

The issue of air return lumi-

naires, still a popular option with

M&E consultants, is another

important consideration.

Modern T16 lamps are designed

for maximum efficiency at high

temperature, so to draw chilled

air across the lamps is likely to

reduce operating efficiency by

as much as 25 %. Supply air can

also be a problem when dischar-

ged in close proximity to a T16

luminaire. The diagram above

shows a solution to the return

air path that bypasses the lamp

compartment altogether. Maxi-

mum air volumes for generic

luminaire types are readily avail-

able.

Please contact the Zumtobel

Staff Technical Office for

advice

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

respectively.

Bypass air handling in the MELLOW LIGHT IV, with either TC-L or T16 lamp

options, avoids any cooling of the lamp.


43/140

4. Ceilings and their

Influence

on Lamp Choice

In an ideal world, lighting which

incurs an ongoing revenue cost

in a building, should dictate the

choice of ceiling. However for

good reasons to do with lettable

space, there is a growing trend

for 500 mm as the base building

module, which gives 1500 mm

multiples for partition choice.

A 500 mm square luminaire

size is not a good choice with

respect to lamp choice, because

it narrows the options to TC-L

and TC-D lamps which have the

relative high brightness and are

less efficient than current best

practice T16 lamps.

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

750 mm square ceiling grid, or

into a 1500 mm square tartan

grid ceiling.

The 750 mm square luminaire

uses 600 mm T16 lamps in a

luminaire variant that has extend-

ed flanges as shown in the pic-

ture above.

A fully updated matrix of these

various options is available from

our Technical Department.

Contact us on:

[email protected]



44/140

Further Considerations

in Workplace Lighting

5. Colour in the

Workplace

The issues of colour and colour

temperature in the modern

workplace are increasingly

important to consider, as the

technologies for achieving

such effects proliferate almost

daily. Below we assess the

most common techniques and

their associated problems and

opportunities.

Lamp Colour Temperature

The issue of lamp colour tem-

perature is a perennial issue

in office lighting design. In

bygone days the usual choice

was a lamp with an interme-

diate colour temperature of

around 4,000 K. However, the

situation is now more compli-

cated as a result of three main

shifts in technology and re-

search data:

Firstly, premium offices will

more often than not have a

dimming facility, at least within

the daylight zone. In the quest

to match more closely the arti-

ficial lighting with daylight

within those zones, there is

now a wider acceptance of

cooler colour temperatures.

Secondly suspended fixtures

with variable flux fraction ratio

(FFR), such as Zumtobel Staffs

LA TRAVE fitting, are gaining

greater acceptability. Here it is

possible to use a different

(usually cooler) colour tem-

perature lamp for the upward

component, and a warmer

colour temperature for down-

ward focal glow (see page 35).

Thirdly, as explained on page

15 there is much evidence

from the so-called third eye

research to support the use of

extra high colour temperature

lamps with a high blue con-

tent, in 24-hour workplace

facilities, to help maintain sus-

tained alertness.

Secondary Lamp Systems

The latest version of the

acclaimed, and much-copied,

MELLOW LIGHT system

MELLOW LIGHT IV has the

potential to incorporate sepa-

rate colour lamps, which can

be used to create distinct

areas of colour, in addition to

white light (above and below).

These might be used to add

coloured highlights within an

otherwise bland space.

2700 K 6500 K

MELLOW LIGHT IV Balanced

Recessed luminaire

Surface-mounted luminaire


45/140

Coloured Tints for Mood and

Identity

While intense areas of satu-

rated colour, which can be

visually distracting, are not

advisable for office spaces,

Zumtobel Staff does offer an

option for coloured additive

tints inside some luminaires,

such as MELLOW LIGHT

and PERLUCE. These can be

used to add visual interest,

to create distinctive moods

within the space or to desig-

nate specific zones or work

functions, to aid team cohe-

sion and/or orientation in large

buildings.

Working with Self-Illuminat-

ing Surfaces

ACTIVE LIGHT WALL systems

or internally illuminated screens

hiding RGB colour changers,

are the latest methods for

adding colour to vertical sur-

faces, such as walls. By using

RGB colour mixing, a huge

palette of colours can be cre-

ated and distributed over even

large surface areas. These can

range from subtle pastels to

intense, saturated hues. The

use of intense coloured effects

could be most effective in pro-

viding focus and impact in

meeting spaces, break-out

zones or common parts. Or

alternatively colour could be

used to mimic windows in day-

light-starved, deep-plan spaces.

6. Discomfort Glare

(UGR)

Within the UK, the concept of

glare limits has been around

since 1961. However during the

era of low brightness VDT

louvre products, with very low

UGRs, the subject was very

rarely addressed. Now with the

growing prevalence of so-called

dual component fixtures,

glare calculations are again

necessary.

The latest Dialux design soft-

ware offers a Glare calculation

module which is very useful.

One aspect of this programme

is a new ability to calculate

UGRs from an array of counter-

rotated luminaires. This can be

used where the side view,

which is the brightest aspect

of the luminaire, exceeds the

recommended glare limit for

offices of UGR 19. If alternate

luminaires are set endwise and

crosswise, very often the UGR

will be compliant.

Please contact the Zumtobel

Staff Technical Office for more

information.


Balanced colour luminaires used in a refectory. Colour changing: morning, noon and night


46/140


* Calculated on the projected fuel mix for the grid 19982000. 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 UKs 2002 National Atmospheric Emissions Inventory (NAEI) www.naei.org.uk for long haul flights

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**

CO2 EMISSIONS a comparison


47/140

7. Energy

The measurement of energy

use is a crucial issue in todays

post-Kyoto world. However, the

various methods and formulae

for measuring energy use in

relation to lighting are both

confusing and in some cases,

incompatible. In this section we

chart the variety of techniques

of assessing energy/power

loading in rel

Documents

Lighting Handbook Lighting for the Workplace