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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 – – – – –
nomics
of this guide to office lighting. In combination they correspond to Zumtobel Staff’s central lighting – – – –
installation maintenance operation energy environment
Eco
able light levels – lie at the core
**
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
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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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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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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.
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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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 CO 2 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
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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
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
benefits – as their name suggests,
dubbed “eyebrow glare”. This 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 CO2 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/CO2/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