conference lighting

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LIGHTING GUIDE

THE VISUAL ENVIRONMENT INLECTURE, TEACHING AND

CONFERENCE ROOMS

LG5 : 1991

The Chartered Institution of Building Services EngineersDelta House, 222 Balham High Road, London SW12 9BS


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The rights of publication or of translation are reserved.

No part of this publication may be reproduced, stored in a retrieval system or

transmitted in any form or by any means without the prior permission of the

Institution.

© 1991

THE CHARTERED INSTITUTION OF

BUILDING SERVICES ENGINEERS

LONDON

ISBN 0 900953 47 0

This document is based upon the best knowledge available at the time of publication. However no responsibility of any kind for any injury, death, loss, damage or delay however caused resulting from the use of these

recommendations con be accepted by the Chartered Institution of Building Services Engineers, the authors or others involved in its publication. In adopting these recommendations for use each adopter by so doing agrees

to accept full responsibility for any personal injury, death, loss, damage or delay arising out of or in connection with their use by or on behalf of such adopter irrespective of the cause or reason therefore and agrees to

defend, indemnify and hold harmless the Chartered Institution of Building Services Engineers, the authors and others involved in their publication from and against any and all liability arising out of or in connection with such

use as aforesaid and irrespective of any negligence on the port of those indemnified.

Typeset and printed in Great Britain by UNWIN BROTHERS LTD.


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Foreword

In 1963 the Illuminating Engineering Society published a remarkable mono-graph entitled Lecture theatres and their lighting which became a standardwork of reference. An updated edition was published in 1973. With thepassage of time, and in a different economic climate, it was felt that a similar work was needed. This Guide covers not only lecture theatres, but teachingrooms, committee rooms, conference and multi-purpose rooms, and rep-resents a wholly new approach to the subject.

CIBSE acknowledges the assistance in illustrating this Guide of ThornLighting Ltd., the University of Cambridge, the University of Nottingham,and the University of Surrey.

Task group

A W S Tarrant ChairmanR I BellF BenthamJ A Lynes A Mitchell

Publications Secretary

K J Butcher

Co-ordinating Editor

V P Rolfe

ContributorsR Anderson

L BedocsK JonesI MacLeanD Poole

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Contents

1 Introduction

2

1.1 The classification of teaching and conference spaces

Lecture theatres and lecture rooms

3

4

5

6

7

8

2.1 Basic lighting and visual needs2.2 Lecture theatres2.3 Lecture rooms2.4 Chalkboards and their lighting2.5 Provision of daylight2.6 What the audience sees2.7 Decoration and furnishings2.8 Switches, dimmers and controls2.9 Audio visual aids considerations2.10 Access and movement2.11 Use for theatrical presentations

Teaching rooms

3.1 Lighting and visual needs3.2 Rooms intended for formal instruction3.3 Rooms intended for interactive learning3.4 Rooms used for practical work

Large conference rooms

4.1 Basic lighting and visual needs4.2 Lighting systems and controls

4.3 Simultaneous interpretation booths

Committee rooms

5.1 Visual and lighting needs5.2 Daylight5.3 Electric lighting5.4 Surface finishes

Multi-purpose rooms

6.1 Lighting needs6.2 General lighting6.3 Suitable light sources6.4 Suspension points and wiring6.5 Controls

Adjoining spaces - corridors, lobbies, ante-rooms etc.7.1 Lighting objectives7.2 Circulation7.3 Waiting areas and lobbies

Emergency lighting

8.1 Escape route signs8.2 Escape route illumination8.3 Hazard areas8.4 Operating conditions8.5 Choice of systems8.6 Classification of systems

8.7 Planning schemes8.8 Planning sequence8.9 Inspection and servicing

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9 Maintenance

9.1 Lighting maintenance9.2 Cleanliness and tidiness

10 The management of lecture and conference spaces

10.1 Visual clutter 10.2 Lecture attendants10.3 Communication between lecturer and projectionist

or projector 10.4 Projection rooms and booths10.5 Equipment rooms10.6 Preparation rooms10.7 Problems of visiting lecturers

Appendix 1 The preparation and use of slides and overheadprojector transparencies

Appendix 2 Dimming systems and equipment

Appendix 3 Theatrical presentations in lecture theatres andconference rooms

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51

References 51

Glossary 52

Index 55


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1 Introduction

When people come together for the purposes of teaching or discussion, it isnecessary for them to be able to see each other properly. Whether it be aformal lecture in some great professional institution, a class in a primaryschool, a conference or perhaps even a commercial presentation in a hotel,it is necessary for all the individuals present to be able to see each other clearly, and to see what is going on. That may sound obvious but we haveall experienced classrooms in which some of the children cannot see what iswritten on the chalkboard, or lecture rooms in which a distinguished speaker has been made to appear grotesque by bad lighting, or multi-purpose roomsin which an elaborately prepared demonstration has been ruined by anunwanted ingress of daylight.

The function of this Guide is to offer advice on the lighting of lecturetheatres, teaching rooms, conference rooms and multi-purpose rooms and onthe visual problems that may arise. It is therefore necessary to discussother matters than simply the lighting equipment and its positioning. Thedecoration and finishes of such rooms, the sightlines, the positioning of

lighting controls and access doors all need to be taken into account. Thelighting is a vital element in such rooms and requirements of lighting shouldbe taken into account from the first stages of the planning.

This point cannot be too strongly emphasised. Lighting is so important tothe functioning of all the premises covered by this guide that it must beconsidered from the very outset of the planning process. By lighting we meanboth natural and artificial lighting; experience shows that whilst muchthought is given to natural lighting, i.e. window design, planning for artificiallighting is often left until far too late in the design process.

However, lighting problems do not only occur in the design of new buildings;equally important questions are those of re-lighting or redecorating existingrooms, and this Guide has been written with this in mind. Questions of safetymust be considered, and so a section on emergency lighting has been included.Consideration has also been given to the lighting of spaces immediatelyadjoining teaching rooms; and sections have been included on the vitalquestions of the management and maintenance of such rooms as far as thevisual problems are involved.

Each chapter has a list of points that the lighting designer should checkbefore finalising any design. The check lists are to be used in this way:-

First, read the questions on the checklist, and compare your answers withthe checklist answers. (Y = Yes, N = No, ? = You need to consider this

item).

Second, if your answers agree with the checklist, then carry on; if theydisagree, then check the chapter for advice; if the answer given is ‘?’ thenyou will need to understand what the effect of your answer will be. Makesure that you understand the reasons behind the answers, and check thechapter for more information.

1.1 The classification of teaching andconference spaces

For the purposes of this Guide, teaching and conference spaces are classifiedin the way indicated below, and this terminology is used throughout.

1.1.1 lecture theatres Rooms used for the delivery of formal lectures with raked floors and/or balconies or galleries and with fixed seating.

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1.1.2 lecture rooms

1.1.3 Teaching rooms

1.1.4 Rooms used for

practical work

1.1.5 large conference

rooms

1.1.6 Committee rooms Rooms used for meetings capable of seating up to roughly 30 persons.

1.1.7 Multi-purpose rooms Rooms used for a wide variety of purposes, such as school halls, assemblyrooms, function rooms, church halls.

1.1.8 Adjoining spaces

CIBSE LIGHTING GUIDE

Rooms used mainly for the delivery of formal lectures, with basically flatfloors and fixed seating. This category includes rooms with a raised step or podium for the lecturer, and rooms with one or two raised steps towards therear of the seating.

Rooms used mainly for class teaching purposes, with flat floors and no fixedfurniture except possibly chalkboards and projection screens. Such roomswill usually have a seating capacity of less than 60.

Rooms used regularly for class teaching purposes, without large permanentpieces of apparatus set up. Such rooms will usually have a seating capacityof less than 60. This category will include many teaching laboratories.

Rooms used mainly for conferences and meetings at which people mayaddress the audience from almost any point in the room. Such rooms willusually have a capacity of more than 60.

Foyers, ante-rooms, lobbies and corridors immediately adjoining those spaceslisted above.

2 Lecture theatres and lecture rooms

The choice between a lecture room (basically flat) and a lecture theatre(raked) will be determined by the audience size. If it is less than 60 there islittle point in providing a raked room. If it is more than 80, raked seating isessential, unless the lecturer is raised on a stage or podium.

2.1 Basic lighting andvisual needs

The lighting in a lecture space must reveal the lecturer to the audience andthe audience to the lecturer and also provide for the other visual tasksinvolved. These include observing demonstrations, reading what is writtenon the chalkboard, and the taking of notes. Note-taking has to continue whenslides, films or video presentations are used.

The lighting in a lecture theatre may conveniently be thought of in termsof that for the audience area and that for the demonstration area, thoughthis distinction should not be pushed too far; in many lecture theatres,especially smaller ones, the audience area lighting may well function asgeneral lighting and provide much of the illumination in the demonstration

area as well.

2.2 Lecture theatres

2.2.1 lighting the audience

area

For the audience area the basic choice is between incandescent and fluor-escent lighting. Incandescent light is readily controllable in intensity anddirection, and is often preferred on aesthetic grounds. However it is inefficientin terms of energy usage, doubly so in the case of lecture theatres, since theheat which it introduces to the building has to be removed (at great expense)by the air conditioning system. Fluorescent lamps of modern types, withgood colour rendering, are very much more energy-efficient and in thosetheatres which are heavily used e.g. in schools and colleges, energy economics

will usually dictate their use. Other types of discharge lamp (e.g. high pressuresodium) are not suitable, since if they inadvertently get switched off it maybe several minutes before they can be relit.


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LECTURE, TEACHING AND CONFERENCE ROOMS

Whatever type of lighting is used, the luminaires must be positioned so asnot to create glare problems either for the audience or the speaker, as shownin Figure 2.1. This means that, unless the ceiling is exceptionally high, theluminaires must be mounted on, or recessed into the ceiling. Figure 2.2

Figure 2.1 Luminaires at positions such as A,B

are close to eye level in the back row seats and

may cause intolerable glare.

Figure 2.2 Ribs in a ceiling used to act as glare shields.

shows that when the ceiling is not a flat horizontal surface it may be possibleto make use of its shape to conceal the luminaires from the direct sight lineof the audience, provided that they do not become bad glare sources for thelecturer. The glare index at any point of the audience area should not exceed16.

When incandescent lighting is used, luminaires of the downlighter typeshould be avoided. Although these are often used in legitimate theatres andconcert halls, they produce a poor modelling of people’s faces, with the resultthat the lecturer cannot see the reactions of the audience. When surfacemounted luminaires are used, they should not be of the type which producea distracting halo on the ceiling around them. Care should also be taken withluminaires mounted close to the walls to avoid the scalloped effect on thewall, which can also be distracting.

When fluorescent lighting is used, ceiling mounted luminaires of the recessedor semi-recessed type may be used. The latter are preferred to prevent theceiling appearing too dark. In order to avoid note-taking shadows, theluminaires should be mounted with their long axis parallel to the rows of seats; it is not usually practicable to correlate the rows of luminaires with therows of seats beneath. The average illuminance on the working plane (usually0.85 m above the floor) should be above 200 lux. Bare fluorescent tubesshould not be used if they are visible either to the audience or lecturer.

If the ceiling is white or of a light colour and is of uncluttered design, indirectlighting may be used for the audience area, but the energy costs will behigher. This method produces illumination which is quite free of glare, butis felt by some to produce a soporific effect. In practice the light sourcesusually have to be concealed in the cornices. Traditional uplighter fittingscause obstruction to some of the sight lines and psychologically provide abarrier between the lecturer and some parts of the audience and are best

avoided.

Lamps used should be of colour rendering group 1B, i.e. their CIE generalcolour rendering index (Ra) should be greater than 80. The common 'white'

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2.2.2 Lighting the

demonstration area

and 'warm white’ fluorescent tubes do not meet this requirement. An efficientsolution is offered by triphosphor fluorescent lamps.

In small lecture theatres and any theatres that have an unbroken horizontalceiling it is a good plan to carry the general lighting forward to serve thewhole area, and to add additional lighting as described below. This techniquedoes not emphasise any division between the demonstration and audienceareas. In very large lecture theatres, e.g. Figure 2.3, and especially thosewhere the ceiling height is reduced at the front it is advisable to use quite

separate lighting systems for the demonstration and audience areas. Sincethe demonstration area lighting needs to be carefully directionally controlled,only incandescent lighting is suitable.

In small lecture theatres, internal reflector spot lamps may be used, or miniature low voltage luminaires designed for display use. In larger theatresluminaires designed for stage lighting may be used. The lamps or luminairesshould preferably be recessed or otherwise concealed from the view of theaudience. They may otherwise become very obtrusive and give the theatre atheatrical look, or even the aspect of an operating theatre.

The position and angling of luminaires in the demonstration area is critical.

The best alignment for ceiling mounted luminaires is about 45° to thevertical, and between 30° and 45° to the side. If the angle is near the verticalit may produce grotesque shadows on the lecturer’s face, and if it is near thehorizontal the lecturer may be dazzled when attempting to address theaudience. Similar considerations apply to luminaires mounted on the sidewalls. Illuminance at table top height in the demonstration area should be

Figure 2.3 Example of a large lecture theatre.

higher, but not more than double those of the audience area. The rec-ommended values are 500 lux for the demonstration area and 300 lux for the audience area.

Lighting provided specifically for the lecturer to read notes when the theatreis darkened for the purpose of slide projection needs careful attention. Theproblems are that either light direct from the source, or light reflected from

the notes and desk, may fall on the screen and spoil the appearance of theprojection; it takes very little stray light of this kind to ruin the effect of agood colour slide. The best solution is to incorporate carefully shielded low

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Figure 2.6 Fan shaped lecture theatre.

Figure 2.7 Modified fan shape with angled

straight rows.

2.3 lecture rooms

2.3.1 Lighting

There can be little social contact between different members of the audience,and this is disadvantageous from two points of view: (a) it discouragesaudience participation and (b) it does not facilitate or encourage discussionand questions after a lecture.

For these reasons, the curved rows in Figure 2.6 are to be preferred using afan shaped plan. This arrangement has the disadvantage that if the room isonly two-thirds filled all the audience may be in the back half. Figure 2.7

shows a good design compromise with at least half the length of the sidewalls parallel so as to limit the length of rows at the back. If a projectionroom or booth is provided it must not jut out into the back rows, as thiscreates an unhappy sense of division in the area. It is most important in anylecture theatre that there is an adequate space in the demonstration area. Inpractical terms, this means that there should be at least 3 m (10 feet) betweenthe front wall and the feet of people sitting in the front row. This notonly allows an adequate area for demonstration purposes and improves thesightlines, but it gives the theatre a spacious quality as in Figure 2.3. If thefront wall is too close to the seats the theatre will look cramped, and have aclaustrophobic atmosphere.

Because of the smaller dimensions, the audience area lighting in lecturerooms will usually serve the demonstration area as well. It is desirable thatthe lecturer and the immediate surroundings be a little brighter than the restof the room, and this can usually be effected by the use of a few incandescentlamps of the reflector spot type directed towards the lecturer. However theymust be carefully positioned so as to avoid severe glare to the lecturer; usuallythis will mean that they have to be mounted either on the side walls, or onthe ceiling adjacent to the side walls, the positions are shown in Figure 2.8.

If a fixed lecture bench is installed (which is not a very happy arrangement)luminaires should not be mounted directly over it for demonstration purposes.In this position they may well cause specular reflections from demonstrationequipment which makes it very difficult to see what is going on. Lighting

from the side is equally effective and spotlights may be mounted in the sameposition as those to light the lecturer.

Figure 2.8 X marks possible positions for spot-

lights in a small lecture room on ceiling or side

walls.

The general lighting should be arranged to produce an illuminance above200 lux at desk level in the audience area. It should be reasonably uniformand if fixed seats are installed right up to the walls the illuminance at desklevel at the wall should not be below 70% of the average illuminance. If there is an aisle next to the wall this does not apply. The lamps used shouldbe of colour rendering group 1B. In order that members of the audience maytake notes whilst slides or overhead projector transparencies are shown, amuch lower level of general illuminance - in the range of 15-30 lux isneeded. Ideally this may be achieved with the use of dimming equipment,but economics in most cases dictate a plain switching arrangement, asdiscussed in Section 2.8. Either a few incandescent pearl lamps in a separatecircuit can be used for slide viewing lighting or a few lamps of the generallighting system can be wired in a separate circuit for this purpose.

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2.3.2 Sightlines and glare Lecture rooms are usually rectangular in plan and experience shows that the best seating plan is that with the lecturing area at one end of the room withrows of seating parallel to the short dimension as shown in Figure 2.9.

Figures 2.10, 2.11, and 2.12 show typical layouts of lecture rooms. In thecase of a lecture room which is basically flat the sight lines may be greatly

Figure 2.10 Sightlines in a lecture room with a flat floor.

Figure 2.9 Good lecture room layout.

Figure 2.11 The sightlines may be improved by raising the lecturer on a step.

Figure 2.12 Sightlines can be further improved by raising the rear seats on one or two steps.

Figure 2.13 Back row glare in a lecture room;

sightlines, and will cause intolerable glare.

luminaires at A and B are very close to the students

improved by raising the latter half of the audience on one or two steps andraising the lecturer on a step. Lecture rooms in general have a much lower

ceiling than lecture theatres, and in the absence of raked seating the sightlines become critical. The lighting equipment should be arranged so that theluminaires do not cause serious glare to the occupants of the rear row of seats, as shown in Figure 2.13, or to lecturer as shown in Figure 2.14. When

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2 . 4 C h a l k b o a r d s a n d

the i r l ight ing

Figure 2.14 Glare to the lecturer caused by inappropriate luminaires.

fluorescent lighting is used the luminaires should be of the recessed or semi-recessed types; if this is not possible they may be provided with the glareshields illustrated in Figure 2.15. It may sometimes be possible to use ceilingribs as glare shields. On no account should bare fluorescent tubes be visibleto the audience.

The glare index at any seat should be less than 16. It should also beremembered that avoiding glare for the audience may create glare for thelecturer; in particular, the lecturer must not be subjected to disability glare.

Figure 2.15 Glare shields placed behind luminaires to overcome the problem of back row glare.

Figure 2.16 shows a chalkboard made difficult to read by veiling glare. Thisis usually caused by the internal light sources or windows. It is thereforeessential that all chalkboards should have a matt surface; the term chalkboardincludes both the traditional blackboard used with chalk, or whiteboards usedwith marker pens,

If a blackboard is used it need not actually be black - a Munsell value notexceeding 4 (reflectance less than 0.12) is satisfactory. Suitable surface coloursare given in DES Building Bulletin No. 9

(2). Note that whiteboards cannot

satisfactorily be used as projection screens.

To keep reflections to a minimum chalkboards should be mounted verticallyon the front wall. They are best lit by ceiling mounted luminaires, similar to that in Figure 2.17, shielded so that the lamps are not visible to the

audience. The best position for a chalkboard luminaire is shown in Figure2.18; a luminaire placed close to the board cannot light the foot of the boardadequately. The illuminance on the chalkboard surface should average 500lux, with a uniformity of 0.25; this can be halved in the case of white boards.

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Figure 2.16 Reflection of a light source in a chalkboard.

Figure 2.17 Ceiling mounted fluorescent luminaire suitable for chalkboard lighting.

Figure 2.18 Choosing position for a chalkboard luminaire.

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2.5 Provision of daylight Almost all lecture presentations require controlled lighting at some stage.For that reason, lecture theatres and rooms are often built with no access todaylight. Equally, people do not like to feel shut in, especially when lecturesare given during daylight hours, and there are many who have a preferencefor working under natural light. In rooms the size of lecture theatres the

provision of natural light in sufficient quantities for working purposes requiresvery large areas of glazing. That is not only expensive from the point of viewof heat loss, but it is difficult to achieve a good blackout, and unless the

windows are north facing there may be severe problems with solar heat gainin summer.

The only way in which an adequate blackout can be achieved in such roomsis by the use of the completely opaque blinds, running in grooves at the sidesto provide a complete light trap. An example of this type of blind is shownin Figure 2.19. Curtains or venetian blinds are not adequate. Blinds should

be of light colour on the inside so as not to present a large black area whendown, and in view of the area of window involved and the need for frequentopening and closing they should be motor operated. Blinds should also be of a light colour on the outside, to prevent excessive solar heat gain.

Figure 2.19 Blind with deep grooves suitable for lecture room use.

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It is often felt that windows in lecture theatres and rooms have to be providedto give the occupants some view of the outside world and to overcome feelingsof claustrophobia, i.e. to provide some visual escape rather than to providelighting. Figure 2.20 shows that very much smaller areas of window can beused, and the problems associated with them much reduced. However, theneed for a perfect blackout remains and again groove enclosed blinds areneeded, though they may be hand-operated.

Figure 2.20 Windows of limited area in a lecture room, provided to offer ‘visual escape’ to the

occupants rather than to admit daylight.

Windows should not be provided in either the front wall or back wall of alecture theatre or lecture room. The former would produce intolerable glareto the audience and the latter would cause serious veiling reflections on thechalkboard.

Skylights should not be provided; they require elaborate blackout arrange-ments and are very difficult to keep clean. In the few lecture theatres wherethey have been installed they are usually kept permanently blacked out.

From the point of view of lighting, it is much better for lecture theatres androoms to be windowless. Since the occupants rarely have to remain in themfor more than an hour without a break, problems of claustrophobia do notarise, although they may well do so in small teaching rooms. Some newer

institutions make extensive use of windowless lecture rooms with entiresuccess. Windowless lecture theatres and rooms require forced ventilationwhich may in turn lead to noise problems, but it should be pointed out thatlarge theatres with extensive glazing have an equal requirement for forcedventilation.

Light traps (e.g. two sets of doors or other effective means for excludingdaylight) should be provided in all lecture theatres and rooms to preventdaylight getting in when the theatre is darkened for the presentation of colour slides. This is particularly so in the case of entrances at the rear of the theatre,which when opened suddenly by a latecomer may allow full daylight to fallon the projection screen. These light traps should also function as soundtraps.

Such doors should not be provided with windows if it is not possible to provide proper light traps. If automatic door closers are installed they should be of a design which allows the door to be closed quickly and silently.

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2.6


What the aud iencesees

The audience should be able to concentrate on the lecturer, screen or chalkboard, and the decoration, furnishings and equipment should not becompeting with the lecturer for attention. The lecturer’s desk, chalkboardand screen must be so placed that they do not obstruct the view of theaudience. If an overhead projector is used, great care must be taken to seethat it does not obstruct either the audience’s view of the lecturer or thelecturer’s view of the audience. Overhead projectors often lead to distractingshadows appearing on the projection screen when slide or film projection is

used. Overhead projectors are best mounted on trolleys so that they can bewheeled out of the way when not required.

2 .7 D ecora t ion andfurn ish ings

Specular reflections of light sources and windows on the chalkboards,sounding boards and glazed portraits should be avoided. Also avoid back-grounds, such as those in Figure 2.21 with disturbing patterns, and back-grounds full of fussy details. The audience’s view of the front of the lectureroom or lecture theatre should be clear and free from visual clutter; in

particular the front wall should be kept clear of pipework, conduits, andventilation trunking. In some cases the luminaires themselves may providevisual clutter, and ventilating diffusers are particularly apt to do so. A wallfull of chalkboards which cannot easily be cleaned results in a dirty-lookinggrey area. See also Section 10.1.

Figure 2.21 Disturbing pattern on the front wall of a lecture theatre.

It is the decoration and furnishings within a lecture theatre or room which,in combination with the lighting determine its appearance and contribute tothat indefinable quality that we usually call atmosphere or character.

There is a great variety of styles available in a number of colours and finishesand a choice from these should be made at an early stage in conjunction withother decorative finishes and furniture. The use of darker colours on the sidewalls of theatres will help concentration. The surfaces of the side walls shouldhave some degree of texture, such as that provided by timber panelling, textilecovered panels, slightly textured plastics or recessed-pointing brickwork.Shuttered concrete is not recommended as it soon gets dirty and is not easy

to clean. In a lecture room without fixed seating it may not be desirable totreat the side walls as a feature, but darker-toned colour can be used behindthe lecturer. Ceilings should be just off-white. Whether white or a tint will

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Figure 2.22 Suitable colours for decoration and furnishings. The colours recommended are specified by their British Standard Colour Numbers (given

below each sample) according to BS 4800 (1984). Owing to the difficulties of colour reproduction, these samples may not accurately match the BS

colours. Designers and specifiers should quote the BS numbers and not attempt to match these samples visually.


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depend on the style of lighting. The colour should always be light but if luminaires are recessed and no light is reflected off the ceiling it will look grey by comparison. Walls should be of a different colour from the ceilingin order to define the boundaries of the interior space and avoid a feeling of claustrophobia.

The co-ordination of the colour and texture of finishes with the lighting is

all-important. The colour rendering properties of the lighting will greatlyaffect the choice of colours and in some cases daylight will have to beconsidered also. When replacement lamps are fitted they should always bethe same as the originals, unless a positive decision is made to re-lamp thewhole theatre with lamps of a more modern type. Dark colours in decorationand furnishings should be avoided and matt or semi-matt surfaces aredesirable as high gloss areas will cause specular reflection and be distracting.Cold blues, dark greys and dull yellows must be avoided, and also colourswhich are very clear and strong in blue and yellow; they are particularlydistorted by some forms of fluorescent lighting.

Colour contrasts of a modest nature are desirable since a bland interior scheme, combined with dim lighting, tends to cause drowsiness amongst the

audience. These contrasts can usually be obtained by careful choice of thecolours of the seating as this presents a large area of colour; mid-toned coloursare best in a definite but not too strong hue. The flooring colour does notcontribute a great deal to the scheme in a lecture theatre. Whether carpet or hard finish a coloured neutral is the most practical choice. Suggested coloursare given in Figure 2.22 with their British Standard references.

2 .8 Sw i tches , d im m ersand contro ls

In any lecture space the lighting controls need to be as simple and comprehen-sible as possible – lecturers are more concerned with their subject matter than light switches. In the main, the only lighting settings needed in a lecturetheatre are:

(a) full normal lighting

(b) audience area lighting reduced to a low level and demonstration arealighting off; for the purpose of line slide projection, but allowing enoughlight for the audience to take notes

(c) all lighting off; for the projection of tone slides, colour slides, and for

the purposes of visual demonstrations.

Abrupt changes in the lighting are disturbing to the audience, and for thatreason dimmers which enable gradual changes to be made are preferable to plain switches, Manually operated dimmers are not satisfactory as it is difficult

to get a smooth transaction from one lighting state to another.

A good system is that in which the only controls are three push buttons,corresponding to the states (a), (b), (c) above. On pushing the appropriate

buttons the dimmers move accordingly. In such installations the time takento go from full-on (a) to full-off (c) should not be too long; about four secondsis sufficient. The very slow dimming speeds used in the professional cinemaand theatre (usually about twenty seconds from full-on to full-off) areinappropriate in lecture theatres; it is frustrating to audience and lecturer alike to have to keep waiting while the lights go down before a slide can beshown. A further advantage of the pre-set push button dimming system isthat several sets of out-station controls may be used and this may save thelecturer a great deal of walking about; an out-station control should also be

provided for the lecture attendant e.g. in the projection room.

If it is not possible to use dimmers on grounds of cost, aless satisfactory, but

acceptable system using plain switches may be used in lecture theatres and

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rooms seating up to 120; dimmers are essential in large theatres. In thisarrangement all of the lighting for the audience area and the demonstrationarea (except the lectern light) is switched by a single switch at the lecturer’s

position which should have a large and clearly marked handle.

A miniature neon or LED indicator, permanently lit, should be provided toenable the lecturer to find it in the dark. In lecture rooms that do not havefixed seating this switch should be on the front wall and a little to one sideof the screen so that the lecturer does not have to walk in front of the screento operate it. The needs of slide projection and note-taking may be met byuse of a few plain pearl lamps in the ceiling (referred to as pilots) under thecontrol of a separate switch. Pilot lights of this kind should provide anilluminance of about 15 lux in the audience area, and should be kept wellaway from the demonstration area and projection area; an example of pilotlights is shown in Figure 2.23.

Figure

shown.

2.23 The small incandescent lamps in this theatre are used alone as ‘pilots’ when slides are

All lecture theatres should be arranged for one person operation as circum-stances inevitably arise where a lecturer has to speak without the services of

an attendant.

Points to particularly avoid in the switching are:

• A plethorasystem.

of switches operating different sections of the general lighting

• Positioning the switches so that they become inaccessible when the projection screen is in use as in Figure 2.24.

• Arranging for some sections of the lighting to be on two-way circuitswith switches at the rear entrance doors. (This arrangement means thatto get all the lights off the unfortunate lecturer has to remember whichswitches to push up and which to push down, and the pattern will be

different every time the room is used.)• Arrangements whereby any

switches outside the room.of the lighting can be controlled from

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2 .9 A ud io -v isua l a idsc o n s i d e r a t i o n s


Figure 2.24 Light switches rendered inaccessible by a projection screen.

It is vital that the various pieces of audio-visual equipment do not obstructthe audience’s view of the lecturer, the projection screen, and the chalkboard,Overhead projectors and television monitors are particularly apt to do this.One solution is to mount the two last mentioned items on wheeled trollies,so that they can easily be moved out of the way (or out of the room) whennot wanted. A common problem is that a single screen will not be suitablefor both slide and overhead projector (OHP) use. To avoid the keystone effectshown in Figure 2.25, the screen needs to be angled in different directions.

Figure 2.25 Example of the keystone effect.

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2 .10 A ccess andm o v e m e n t

Figure 2.26 shows movable screens but these are both costly and bulky, andcan cause unwanted shadows on the chalkboard as shown in Figure 2.27.The simplest solution is to use two separate screens. Many lecturers like touse both systems at the same time, and count upon being able to do so.

Figure 2.26 Movable screens in a large lecture theatre: that on the left is set for an overhead

projector, whilst that on the right is set for slide projection from the projection room.

Figure 2.27 Shadows on the chalkboard caused by a bulky projection screen.

It is advantageous for control cables from the projector to the lecturer’s position to be permanently wired in – this saves having cables trailing acrossthe floor. It is also helpful to have a lockable cupboard at the projector

position, in which it can be kept when not in use.

In both lecture theatres and rooms the question of access is important. Ideallythe normal means of access for members of the audience should be throughdoors at the back, with a separate entrance for the lecturer at the front. Rear

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access for latecomers is essential; it is discourteous and annoying to thelecturer and audience when latecomers attempt to pick their way across thedemonstration area. In larger theatres both front and rear access usually haveto be provided. Provided that latecomers are firmly directed towards the rear doors by a suitably worded illuminated sign when lectures are in progress,front access is quite acceptable; if it leads to a social area it may encouragemembers of the audience to come and converse with the lecturer when the

performance is over.

For the purpose of mounting demonstrations it is important that there should be direct access through which a sizeable trolley may be wheeled to thedemonstration area. However, access doors should not be in the front wallof the lecture theatre or room, where they add to the visual clutter, anddistract attention. The same applies to the doors of preparations rooms,lecturers’ rooms and stores.

All lecture theatres and lecture rooms sooner or later become used for purposes other than that to which they were originally dedicated. Conse-quently all items in the demonstration area should be movable and removable.Lecterns are obtainable which are readily movable, even those embodying

controls for the lighting and projectors. Figure 2.28 shows a removablelectern. Massive permanent benches are to be avoided; they form an effective

barrier between lecturer and audience, and demonstrations may equally well be mounted on a set of tables which can be carried out when not wanted.Experience shows that when demonstrations are mounted, services other than electricity are rarely, if ever, called for and there is little point ininstalling a fixed bench simply to provide terminal points for water, gas, andother outlets. If such services are needed, they are much better installed inwall cupboards where they can be kept both locked and out of sight untilthey are wanted.

Figure 2.28 Lectern embodying controls for lighting and projection which is movable and remov-

a b l e

In some cases, local authority bye-laws require that all exits to a lecturetheatre/room be marked with permanently illuminated exit signs. Light fromsuch signs falling on a projection screen can ruin the effect of colour slidesor demonstrations. They should therefore be aligned so as to be visible tothe audience, but not to throw light on the projection screen.

2.11 Use for theatrical

presentations

Possibly because they resemble legitimate theatres in shape and possibly because they often constitute the largest auditorium in a particular institution,lecture theatres are sometimes chosen as the venue for theatrical present-ations. Such presentations can be greatly helped by the provision of further special facilities, which are set out in Appendix 3. However some of theseare expensive, and consideration will have to be given to the extent to which

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a particular lecture theatre may be used in this way. The general experienceis that the larger the lecture theatre, the more likely it is to be used for theatrical purposes.

Table 2.1 Checklist - Lecture theatres and lecture rooms

1) Compare your answers with the checklist answers. (Y = Yes, N = No, ? = You need to consider

this item)

2) If your answers agree with the checklist, then carry on; if they disagree, then check the section

for advice; if the answer given is '?' then you will need to understand what the effect of your answer

will be. Make sure that you understand the reasons behind the answers, and check the section for

more information.

Can the audience see the lecturer easily? Y

Can the lecturer see the audience easily? Y

Will it be a lecture room or a lecture theatre? ?

Is the audience lighting incandescent or fluor-

escent? ?

Is the audience lighting readily controllable? Y

Are the luminaires positioned not to create glare problems either for the audience or the speaker?

Y

If the ceiling is not a flat horizontal surface, can

its shape be used to conceal the luminaires from

the direct sightline of the audience without

causing glare for the lecturer? Y

Are totally recessed luminaires of the down-

lighter type used? N

Is the modelling of human features good enough

for the lecturer to see clearly the reactions of

the audience? Y

Do any surface-mounted luminaires produce a

distracting halo on the ceiling? N

Do luminaires mounted close to the walls produce a scalloped effect on the wall or any

other patterns which can be distracting? N

Where there is note taking, does the lighting

create multiple shadows of the pen/pencil point

on the paper? N

Are luminaires of the semi-recessed type to

prevent the ceiling appearing too dark? Y

Are fluorescent luminaires mounted with their

long axis parallel to the rows of seats to prevent

note-taking shadows? Y

Is the average illuminance on the working plane

(normally 0.85 m above the floor) above 200 lux

and adjustable? Y

Do the lamps have adequate colour rendering

properties (CIE Class lB)? Y

Is the lighting system designed so that it can be

properly mainta ined? Y

Have arrangements been made to ensure that

maintenance is carried out? Y

In small lecture theatres does the general

lighting extend forward to serve the whole area?

Y

In large lecture theatres is there a separate

lighting system for the demonstration area? Y

Is the demonstration area lighting incandescent

with directional control? Y

Are demonstration area luminaires recessed or

otherwise concealed from the view of the audi-

ence? Y

Is the position and angling of luminaires in the

demonstration area correct (about 45° to the

vertical)? Y

Are luminaires arranged to produce general

illumination over the demonstration area rather

than angled at definite points? Y

The lecturer must be able to read notes when

the theatre is darkened for the purpose of slide projection. Is this provided by the room lighting,

by dedicated lighting, or by carefully shielded

low-power light sources provided in the lectern

itself (preferred)? ?

In this situation, does light (direct from the

source, or reflected from notes or desk) fall

on the screen and spoil the appearance of the

projection? N

In this situation, is the luminance of the notes

low and can it be controlled easily? Y

In a lecture room does the general lighting

produce an illuminance above 200 lux at desk

level in the audience area? Y

In a lecture room, is the lighting in the audiencearea reasonably uniform? Y

In a lecture room, if fixed seats are installed

right up to the walls is the illuminance at desk

level at the wall not less than 70% of the average

illuminance? Y n.b. if there is an aisle next to

the wall this does not apply.

Can a general illuminance of 15-30 lux (on the

desks) be set so that the audience may take notes

whilst slides or overhead projector trans-

parencies are shown? Y

Are chalkboards lighted by suitably designed

ceiling mounted luminaires, carefully shielded

so that they do not cause glare to the audience?

YIs the room windowless? Y

If windows are provided, has adequate blackout

been achieved by the use of completely opaque

blinds, running in grooves at the sides to provide

a complete light trap? Y

Are the blinds of light colour on the inside and

motor or handle operated? Y

Are small windows provided to give the occu-

pants some view of the outside world and to

overcome feelings of claustrophobia? Y

Is the ventilation adequate? Y

Is noise from the ventilation system a problem?

Y

Are light traps provided to prevent the ingress

of daylight when the theatre is darkened for

projection (particularly in the case of entrances

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Table 2.1 Continued

1) Compare your answers with the checklist answers. (Y = Yes, N = No, ? = You need to consider

this item)

2) If your answers agree with the checklist, then carry on; if they disagree, then check the section

for advice; if the answer given is '?' then you will need to understand what the effect of your answer

will be. Make sure that you understand the reasons behind the answers, and check the section for

more information.

at the rear of the theatre which can illuminate

the screen)? Y

Do the light traps also function as sound traps?

Y

Will doors close quickly and silently? Y

[Lecture room only] Could sight l ines be

improved by raising the latter half of the audi-

ence on one or two steps and/or raising the

lecturer on a step? Y

[Lecture room only] Is the lecturing area at one

end of the room with rows of seating parallel to

the short dimension? Y

[Lecture theatre only] Is the rake too steep,

making the audience feel uncomfortable or causing problems with slide projection? N

[Lecture theatre only] Is the seating plan fan-

shaped with curved rows and limited row lengths

at the rear? Y

If a projection room or booth is provided, does

it jut out into the back rows? N

Is there anything which competes with the lec-

turer for attention? N

Do the lecturer’s desk, chalkboard and screen

obstruct the view of each other? N

If an overhead projector is used, does it obstruct

either the audience’s view of the lecturer or the

lecturer’s view of the audience; does it obstruct

the projection path and cause shadows? N

If an overhead projector is used, is it mounted

on a trolley so that they can be wheeled out of

the way when not required? N

Is the audience’s view free of visual clutter? Y

Is the atmosphere too strong nor too bland? N

Have darker colours been used on the side walls

to aid concentration on the focal point? Y

Is the ceiling finish light and off-white? Y

Are the luminaires recessed? ?

Are the ceilings and walls painted in the same

colour all-over? N

Have the colour rendering properties of thelighting and daylight been allowed for in the

choice of surface colours? N

If replacement lamps are fitted, are they the

same as the originals or has a positive decision

been made to re-lamp the whole theatre? Y

Has full advantage been taken of modern lamp

types? Y

Have dark colours in decoration and furnishings

been avo ided? Y

Have matt or semi-matt surfaces been used

throughout? Y

Have colour contrasts of a modest nature been

used? Y

Has adequate consideration been given to the

type of carpet (or other flooring) used and the

patterns of wear that will exist? Y

Are the lighting controls as simple and compre-

hensible as possible? Y

Have the following 3 conditions been provided

and can they be achieved easily? Y

(a) full normal lighting

(b) audience area lighting reduced to a low

level and demonstration area lighting off;

for the purpose of slide projection but

allowing enough light for the audience to

take notes

(c) all lighting off; for the projection of tone

slides, colour slides, and for the purposes

of visual demonstrations

Have abrupt changes between lighting condit-

ions been avoided? Y

Are dimmers with automatic fade controls used,

preferabl y wit h thr ee push buttons, cor re-

sponding to the three control conditions (a), (b)

and (c) above? Y

Are the transition times (fade up and down)

acceptable (about four seconds)? Y

Has a suitable number of out-station controls

been used to provide flexibi lity and ease of

use, and has one been provided for the lecture

attendant e.g. in the projection room? YIf dimmers are not used because of cost, does

the lecture room seat less than 120, and is the

control system flexible and easy to use. Y

If dimmable fluorescent lighting is required, is

it correctly designed, installed and maintained

to ensure satisfactory dimming from full bright-

ness to a level of about 15% of full brightness.

Y

Can the type of lamps selected be dimmed with

the circuit proposed? Y

Does the fluorescent lighting use high fre-

quency control gear (20 - 40 kHz) to minimise

acoustic noise and provide simple, reliable dim-

ming? Y

If fluorescent lighting is switched rather than

dimmed, will it start cleanly without noise or

flickering? Y

If full dimming of the fluorescent lighting is not

provided, then are fluorescent and incandescent

lighting mixed with the latter on dimmer control

for slide projection? Y

Is the dimming equipment and associated wiring

designed to keep radio frequency emission to

the minimum and is other electronic apparatus

carefully screened to prevent interference being

picked up? Y

Is the lecture theatre arranged so that it can be

used for one person operation? Y

Are switches or controls positioned so that they

become inaccessible when the projection screen

is in use? N

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Table 2.1 Continued

3 Teaching rooms

3.1 Lighting and visualneeds

The activities which take place in teaching rooms fall into three categories,which require different styles of lighting, and these are discussed separatelyin this chapter. One category covers the traditional type of teaching wherestudents sitting at prescribed places are addressed by a teacher speaking fromanother prescribed place - a process described by Joad as “.... the transfer of information from the notebook of the teacher to the notes of the student

without passing through the minds of either.” This style of teaching isreferred to here as formal instruction.

The second category includes that style of teaching which takes the form of a group discussion, where teachers and students may sit anywhere, a processsometimes irreverently termed the brainstorming session or circle dance.This style of teaching is referred to here as interactive learning.

The third category is that which covers the teaching of practical work suchas metalwork, craft design and technology.

In the case of rooms intended for formal instruction the lighting needs are

similar to those of lecture rooms, except that the students must be able toread from text books at their desks. The students may have to work at thesame point in the room for several hours at a stretch.

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3.2 Rooms intended for formal instruction

In the case of rooms intended for interactive learning, a sympathetic style of overall lighting is needed, so that faces are revealed without grotesqueshadows in any part of the room. Problems such as glare are less important

because students are free to move their seats, and normally will not occupythe same positions for prolonged periods.

Rooms used for practical work - laboratories, workshops, art rooms, craftrooms and the like, involve visual needs and tasks which are the same asthose found in industry; this is particularly so if the room contains muchfixed equipment e.g. a workshop with lathes and other machine tools.The reader should consult the Code for Interior Lighting

(1) for advice on

laboratories, workshops and sewing rooms. However many rooms used for practical work have to serve a wide variety of purposes and the visual needsof these are discussed in Section 3.4.

Whichever style of teaching is envisaged, it is essential for the lightingdesigners to understand the users’ intentions and their design implications.

In a room planned specifically for ‘chalk and talk’ the role of the windowsis as much to provide visual contact with the outside world as to provideworking daylight with a specific daylight factor. Table 3.1 shows the Depart-ment of Education and Science requirements for windows in the UK.

Table 3.1 Department of Education and Science guidelines(3)

If daylight is to be the principal illuminant the uniformity of the naturallighting is likely to be as important as the average daylight factor. Theuniformity should be acceptable so long as two conditions are fulfilled:

•Figure 3.1 The no-sky line, which is the locus

No substantial part of the working plane shall be beyond the no-sky

of points beyond which it is impossible for anline, shown in Figure 3.1.

occupant to see any part of the sky. • In a room daylit from one side, the sum of ratios (l/w + l/h) shall notexceed 2/(1- p).

where:

l = depth of room, normal to window wall, as shown in Figure 3.2.

w = width of room, parallel to window wall.h = height of window head above floor.ρ = area-weighted average of surface reflectances in half of room

remote from windows.

On no account should the chalkboard be placed on a wall containing awindow and it is advisable that it should not be placed on a wall oppositewindows (see Section 2.4).

Figure 3.2 Limiting room proportions. Windows will need blackout facilities. These can be checked by standing infront of the projection screen. No sky should be directly visible from any

point on the screen. Curtains should be able to meet this criterion, assistedif necessary by ‘Velcro’ fasteners; the material should be suitable for blackouts.

Blinds in vertical rebates would be more effective, but mechanically lessreliable. The blinds themselves need not be dark in colour. If one side of the

blind is dark that side should face away from the window, as an absorbentsurface immediately inside a window exacerbates summertime over-heating

problems.

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3.2.1 Electric lighting

3.2.1.1 Desks

3.2.1.2 Teaching space

The electric lighting has three principal roles; to light the desks, the teacher,and the chalkboard.

For secondary schools, colleges and buildings used extensively after dark the DES Guidelines

(3) recommend a general illuminance of at least 300 lux. This

is best achieved by tubular fluorescent luminaires chosen to limit the glareindex to 16. The contrast rendering factor (CRF), which should be 0.8, should

be maximised by positioning of the luminaires. The classical precept ‘lightover the left shoulder’ meets both these requirements, at least for right-handed students.

Lighting for the teacher’s space should always be switched separately fromthe rest of the room. It may be worth considering a different type of luminairefor this area. The teacher’s face should be sympathetically revealed. A vector/scalar ratio between 1.5 and 1.8 would be suitable. The vector directionshould be such as to facilitate lip-reading. The background luminance should

preferably be slightly lower than the luminance of the teacher’s face. Thismay be difficult in the case of teachers with dark skin tones, but in that casea light background would be particularly inappropriate. Light switches should

be handy to the teacher and not local to each luminaire.

3.2.1.3 Chalkboard Chalkboards need not be black, but should have a Munsell value not exceeding4 (or reflectance not exceeding 0.12): DES Building Bulletin No. 9

(2) illustrates

a range of suitable surface colours. Shiny finishes are unsuitable for chalkboards, as shown in Figure 2.16. The position of a chalkboard luminaire ismore important than its optical design. Figure 2.18 illustrates the principlesinvolved. The luminaire should be as far from the chalkboard as possiblewhilst remaining above the dashed line. A luminaire close to the board cannotilluminate the foot of the board satisfactorily, see also Section 2.4.

Purpose-designed fluorescent luminaires are available for chalkboards. A pair of PAR 38 (internally silvered incandescent reflector flood lamps) positionedto light across the board from opposite sides have the disadvantage of shorter

lamp life. However, they can be used for other display purposes.

3.2.2 Decoration The wall behind the teacher should be as simple and uncluttered as possibleand preferably be of a low chroma colour, so that the teacher may be easilyseen. If there is a very light wall behind the teacher, the result can bedazzling, and so be tiring to the students. This does not mean that all surfacesshould be sombre or dark; on the contrary a desirable freshness of atmospherecan be achieved by using a variety of colours. As a general rule it is comfortableto have the window walls a light colour, though not white. A light off-whitecan be used for the ceiling, rather than dead white, particularly if the roomhas a cornice to divide the ceiling from the walls. If wallpaper is used, itshould either be plain or have only a very restrained pattern.

3.3 Rooms intended for interactive learning

3.3.1 Daylight Good window design can make an important contribution to a room usedfor interactive learning both by providing a variety of views and by naturallighting. In the UK it is a requirement of DES that all teaching spaces inschools should be daylit. The daylight factor distribution is not of major importance; activities which need plenty of daylight can gravitate to a window.Generally an average daylight factor of 5 per cent or more will ensure thatthe room is cheerfully lit during daylight hours. An average below about 2

per cent will require continuous electric lighting unless photoelectric controlsare installed. Where possible, opening windows should be placed in morethan one wall, to soften shadows and to permit cross-ventilation on sunnydays.

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3.3.2 Electric lighting

3.3.3 Decoration

3.4 Rooms used for practical work

The DES heat wave temperatures can be checked using the admittance procedure

(4). See also the BRE Environmental Design Manual

(5). The DES

Guidelines(3)

recommend that the resultant temperature should not exceed27°C during the school year. This can normally be achieved with cross-ventilation and a simple curtain drawn across sunlit windows. If cross-ventilation is impossible the curtains may need a reflective lining facingoutwards; the admittance calculation will show if more radical design modifi-cations are needed in a given instance, to reduce the resultant temperature.

Curtains serve both to provide a degree of blackout sufficient for most portable visual aids, and to provide acoustic absorption which is essential for informal learning without distraction. In general, sunlight is not an overriding

problem for informal teaching. A student who feels dazzled or overheatedhas only to move away from the window or to draw a curtain.

The electric lighting in an informal teaching room should be gentle andunassertive. The DES Guidelines

(3) require a minimum illuminance of 150

lux at any point on the working plane.

Luminaires should be carefully chosen to provide a relaxed atmosphere.Compact fluorescent luminaires may be particularly suitable. Light switching

should be accessible and flexible; block switching is not suitable.

As face-to-face communication is important it is worth checking the vector/scalar ratio, which from all viewing angles should be between 1.5 and 1.8.The lamps chosen should be of colour rendering group 1B. The glare indexwill be relatively unimportant since students experiencing discomfort couldsimply move their seat.

Visual aids such as overhead projectors, slide projectors and video or TVmonitors should be portable, and suitable for use under conditions of imper-fect blackout. Switched socket outlets should be available in pairs, not morethan 3 m apart, at skirting height of 0.3 m around the walls. Overhead

supplies are also desirable, and preferable to floor sockets.

By its nature, interactive learning needs a relaxed, informal, and quietenvironment. All furniture should be movable; wall-to-wall carpeting and

preferably, curtains should be provided.

A fixed blackboard would be unhelpful. Instead each wall might contain awhite steel marker board with magnets to support newsprint or drawings, or a cork pinboard to hold ‘Velcro’ or sandpaper-backed cut-outs. All surfacesshould be capable of accepting temporary adhesives without peeling or leaving a mark.

Reference has been made in Section 3.1 above to the visual needs in roomsused for practical work. In recent years there have been great changes in theway traditional subjects have been taught. Teaching spaces are increasingly

becoming more flexible in use with functions ranging from industrial tooffice environments. The computer is no longer confined to special rooms,

but computer terminals or personal computers may be used almost anywhere.If computers with visual display units are to be frequently used then Lighting Guide LG3: Areas for visual display terminals

(6) should be consulted. It is

particularly important to avoid specular reflections of light sources in VDUscreens.

A very large range of activities are to be found in secondary school craft,design and technology departments and they may change throughout the

course of a year. The illuminance over the working plane (0.85 m above thefloor) should be above 300 lux, and the glare index below 16. If work involving accurate judgement of colour (e.g. art, dyeing etc.) is to be done,

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the lamps should be of colour rendering group 1B. Visual tasks such assewing will require temporary local lighting.

In all cases the teacher occupies no fixed position, but spends time at the benches, machines and tables as needed. The main requirement is that goodsupervision is necessary. In most rooms there will be a teaching wall fromwhere more formal instruction will be carried out with the students sittingor standing by their machines, benches or tables. Detailed instruction, formalor informal will be carried out in another room, classroom, seminar room or small group room, and the design of these spaces should follow the advicein the previous chapter.

Laboratories can take on similar informal arrangements with movable tablesand service pillars so that a variety of layouts can be provided. More formalarrangements exist in tertiary education. In both cases, as with craft, designand technology, there is usually a teaching wall. As with other teachingrooms in schools, it is a DES requirement

(3) that they are largely daylit, but

it is more important that sunlight is excluded because of disability glare andthe danger of rendering bunsen flames invisible. Discharge lamps (other thanfluorescent tubes) should not be used to avoid stroboscopic effects on rotatingmachinery.

Table 3.2 Checklist - Teaching rooms

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Table 3.2 Checklist - Teaching rooms

4 large conference rooms

4.1 Basic lighting andvisual needs

The basic visual needs in a large conference room are that all members of the audience can see the chairman and central officers clearly, and that all persons present should be able to see each other reasonably well in order that a proper dialogue may take place. Many presentations in conferencerooms, e.g. the reading of scientific papers, are tantamount to formal lectures,and the lighting needs are similar to those of lecture theatres. However conference rooms are also often used as cinemas or theatres and the lightingmust be capable of meeting those purposes also.

Specifically the lighting must provide adequate illumination for reading or taking notes at any point, good but not excessive modelling and good colour rendering.

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(b)

(c)

4.2

It must also be flexible and controllable from a single point, must be absolutelysilent and produce no thermal discomfort. Careful co-ordination of thelighting design with the interior decoration and with the heating andventilating system is essential. Absolute blackout facilities will be needed,and if the room is to be used for lecture demonstrations adequate power supplies should be available.

Large conference rooms have a good deal in common with large lecture

theatres, and much of the information in Sections 2, 7, 9, and 10 applies tothem. Conference rooms usually have a clearly defined area where the major

part of the action takes place, corresponding to the demonstration area of alecture theatre, and a clearly defined audience area. But the activities in aconference room differ from those in a lecture theatre in these ways:

(a) The audience may be present for long periods, often on several suc-cessive days.

The proceedings although of a formal nature involve interaction between members of the audience and they must be able to see eachother clearly.

Conference participants must be able to move easily between the

demonstration area and the audience area.

(d ) Simultaneous interpretation facilities may be required.

Item (a) above requires that participants should be able to move in and outof the room whilst proceedings are in progress with the minimum of disturbance, and the seating should be arranged accordingly, with a greater ratio of gangway space to seating space than is the case in lecture theatres.It is important that participants can both get in and out without disturbingthe projector beam if one is in use.

In the UK it has always been the custom that those who contribute to a

discussion should do so from their seats, but in many countries of the worldthis is not so. A person wishing to speak must seek the chairman’s approvaland then get up from his seat and go to a central podium to speak.

The points made in Section 2.2 relating to the layout of the seating applyequally here. Cloakrooms, toilets, refreshment facilities and spaces where

participants may relax should be provided immediately adjacent to largeconference rooms.

Lighting systemsand controls

The lighting requirements of the demonstration area of a large conferenceroom will be similar to those of a lecture theatre, but all lamps should be

controlled by dimmer. Large conference rooms are likely to be used for theatrical performances; consequently provision should be made for easilyrigging additional lighting equipment. The particular requirement is thatappropriate wiring is provided in the shape of numerous circuits terminatingin socket outlets at the points where additional spotlights are likely to bewanted. These circuits may be controlled from a stage lighting control systemoperated from the projection room; in a very large conference room thelighting is likely to be so complex that a system of this kind, under permanentcontrol of an attendant is advisable in any case. If it is known that a largeconference room will be used for theatrical presentations further specialfacilities may be advisable. These are described in Appendix 3.

The lighting of the audience area, and the appearance of the whole arecrucial in a conference room. The audience must not only be able tosee each other clearly, but should not appear grotesque. For that reasondownlighters are not recommended; they produce shadows under the eyes

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4 . 3 Simultaneousinterpretationbooths

which are not acceptable, this is shown in Figure 4.1. If the ceiling is plainwhite, then recessed or cornice lighting may be used, provided that there issufficient direct lighting in the demonstration area to provide a modest degreeof ‘sparkle’. If this is not the case, it is worthwhile introducing a few smallincandescent luminaires for this purpose. The furnishing and decorationshould not be too dark, as light reflected from the floor and furniture willsignificantly improve the modelling of participants’ faces. The points madeabout visual clutter in Section 2 and 10 apply equally to conference rooms.

Figure 4.1 Grotesque modelling produced by downlighters.

Strict specifications are laid down for the lighting of interpretation booths.See IS0 Standard 2603

(7). Care must be taken that light from them does not

spill onto the projection screen.

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Table 4.1 Checklist - Large conference rooms

5 Committee rooms

5.1 Visual and lightingneeds

The basic functions of the lighting, be it daylight or artificial are:

• to enable the committee members to see each other clearly and withoutglare.

• to enable members to read their papers and make notes.

• to enable committee members to see wall mounted displays.

It should be remembered that committees sometimes have to work under some stress, especially when unpleasant or unpopular decisions have to bemade. The luminaires should be unobtrusive, and glare kept to a minimum.

5.2 Daylight Committee rooms should always have some natural lighting; windowlessrooms are unacceptable for committee purposes. The essential problem of natural lighting in a side-lit committee room lies in the fact that occupantson different sides of a table are likely to be exposed to different forms of inconvenience. Those facing a window may suffer glare, and see their colleagues opposite with features in shadow silhouetted against a bright sky.

Those with their backs to a window may cast a shadow on their own papers.One possible approach is to ensure that the chairman faces the window andcan control both the curtains and the electric lighting. This arrangement

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5.3 Electric lighting

5.4 Surface finishes

ensures that the chairman’s face is clearly revealed, that there is no visualdiscomfort, and that the faces of other participants can be seen comfortably.If this can be achieved, it is unlikely that others will have difficulty in seeingone or another.

Pinboards and flipcharts should not be seen next to a window: disability glarewill make them harder to read even when discomfort glare is quite acceptable.They should also not be placed where they may reflect a shiny image of the

window. The prescription above, with the chairman facing the window, takescare of these problems too.

The geometry of lighting should correspond to the geometry of the conferencetable, defining it as the focus of activity within the room. This does notnecessarily mean that the table should be the brightest surface; downlightsare particularly unsuitable as they cast harsh shadows, generate shiny reflec-tions in a polished table-top and tend to leave walls and ceilings in relativedarkness. The illuminance on the table should be about 300 lux, and theglare index at any point of the room should be below 16.

The light distribution should produce a vector/scalar ratio within the limits

recommended in the Code for Interior Lighting

(1)

.Supplementary display lighting will be required for wall-mounted charts etc.This is governed by the same geometrical constraints as chalkboard lighting,see Section 2.4. The display lighting should preferably be dimmer-controlled.Careful design of a committee room will remove the need for easels and

portable projection screens, and for ad-hoc arrangements of slide projectors,overhead projectors and blackout facilities.

The background luminance should ideally be slightly lower than the lumin-ance of the occupants’ faces.

Dark walls are more suitable for formal boardrooms. Very light coloured

walls can give a clinical feel. A few small pictures or ornaments can do muchto improve a committee room, but large and complicated features which maydistract the attention should be avoided. The floor carpet should not be verydark.

Table 5.1 Checklist — Committee rooms

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6 Multi-purpose rooms

6.1 Visual and lightingneeds

The lighting designer should be involved with the architect and interior designer from the start of the planning process. In attempting to design asuitable installation for a multi-purpose room the first requirement is for thedesigner, in consultation with the client, to draw up a list of the purposesenvisaged for the room and an order of priorities of use. The prime lighting

needs in terms of illuminances and the controls needed for each separateactivity can thus be tabulated and if any common pattern exists it will beevident; in that case the lighting can be designed accordingly. However, inmany cases no common pattern will emerge and the designer will have to

produce a compromise design.

There are a few basic points, discussed below, which should be consideredat the start of the design process. These are excluding daylight, stage lighting,and accommodating large chandeliers.

The next requirement is for the lighting designer to determine whatmaximum value of illuminance is required and for how long. This willdetermine the nature of the main light sources. The designer will also haveto consider whether a direct or indirect lighting system is used.

6.1.1 Excluding daylight Daylight should preferably be excluded. Multi-purpose rooms require lightingthat is flexible and controllable to a high degree and daylight is not so. If windows, rooflights or skylights are to be provided they should be fitted withlight tight blackout blinds of the type described for lecture theatres in Section2.5. This is particularly so in the case of skylights.

6.1.2 Stage lighting

6.1.3 Chandeliers

If the room has a definable stage area, then the lighting for it should beregarded as stage lighting and designed accordingly.

If large chandeliers are to be used, they should be thought of as decorative

features rather than the main source of illumination. They can very easilyobstruct both sightlines and the beams of spotlights and their use is notrecommended. If they are used they should be dimmer controlled along withthe rest of the installation.

6.2 General lighting The function of the general lighting in a multi-purpose room is to providean overall uniform illuminance of acceptable colour rendering which is freefrom glare, and which may be dimmed. The design survey mentioned abovewill indicate the illuminance needed at working plane height e.g. 0.85 mabove the floor. If no such survey can be made the designer should aim for

a value of about 150 lux. If it is known that the room will be used regularlyfor examinations then the provision should be for 300 lux. The colour rendering should be of group 1B

(1).

With the variety of activities that may take place, sightlines may be anywhere,and it is important to avoid glare. This point is very well met if the generallighting is indirect. If a direct system has to be used the luminaires should

preferably be recessed. If surface mounted fittings are used they should haveopaque or diffusing side surfaces, and in no circumstances should bare lamps

be visible. Suspended luminaires should not be used to provide generallighting. Care should be taken in avoiding glare not to overdo it; recesseddownlighters in particular give no glare at all but produce both a modellingeffect on faces which is quite the reverse of what is wanted for a social

occasion and a gloomy atmosphere. The illuminance produced by the generallighting should have a uniformity ratio of a least 0.5 at working plane height,and if the ceiling is low this may be difficult to achieve with downlighters.

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6.3 Suitable lightsources

The main lighting may be either incandescent or fluorescent; in a few caseshigh pressure sodium may be used. Incandescent lighting is extremely flexibleand controllable, though is inefficient in terms of energy usage. Although itscolour rendering is not of the best it is often thought of as the appropriatelighting for social functions. Energy efficiency is not of prime importanceunless certain purposes require the use of the room for extended periods, butthe heat which it generates may have to be removed (at some expense) bythe air-conditioning system.

Fluorescent lighting may readily be dimmed but by the nature of the sourceis less flexible. The term fluorescent lighting includes compact sourcefluorescent lamps which can be used in relatively small luminaires. Fluor-escent lamps can be used to advantage in an indirect lighting system,especially where the tubes can be concealed in cornices, coves, or in thestructure of a ribbed ceiling.

High pressure sodium lighting has a very long warm up time and is thus of restricted value in multi-purpose rooms. However, for some functions, e.g.exhibitions, it may be useful, especially if used to provide indirect lighting.If used for direct lighting the mounting height should be at least 3.5 m.

In those rooms which may be used for sports — especially badminton — care should be taken to see that light sources that will not cause flicker or stroboscopic effects are used. Lighting Guide LG4: Sports

(8)should be

consulted on this point.

6.4 Suspension pointsand wiring

It may be necessary to mount temporary spotlights for many functions andappropriate suspension points should be provided; a space frame ceiling isideal for this purpose. If the room has a definable stage area then provisionshould be made for mounting front-of-house spotlights in the shape of wall

brackets or spot bars mounted below the ceiling and in smaller rooms thatmay suffice for all spotlight mounting. Since wall lighting is often neededfor exhibition and display purposes a ceiling track round the entire room1.2 m in from the wall is a wise provision if ceiling height is less than 4 m.

Where provision is made for spotlight mounting for stage purposes, appropriate wiring runs back to the control point/switchboard must be providedwith separate circuits for each outlet point. Outlet points of this kind arenormally out of reach from floor level and should be provided with socketsto BS 546

(9) (15A round pin type).

The wiring should also provide a plentiful number of normal 13A outletsockets at wainscot level all round the room. These are necessary for exhibition

purposes. Flush fitting floor traps should also be provided where projectorsare likely to be used, and these should contain not only power outlets butwiring and sockets of appropriate type for projector remote control systems.

6.5 Controls Multi-purpose rooms will generally be regarded as places of public resort andthus be subject to local bye-laws. These often require that the lighting controls

be placed in a separate room not accessible to the public, which is awkwardif the room is used for, say, a lecture involving slides and demonstrations.All of the lighting controls should be grouped together so that one individualcan have charge of all of them; the controls are best placed in an adjacentroom with a window into the multi-purpose room. If the room is used as acinema the lighting controls can well be placed in the projection room,

provided that a full-depth window is installed and not just projector loopholes.

A microprocessor control system should be used if possible. This allowscomplete flexibility of control, but also enables pre-set lighting arrangementsto be set up at the push of a button so that it can be used by unskilledoperators.

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Table 6.1 Checklist — Multi-purpose rooms

7 Adjoining spaces — corridors, lobbies, ante-rooms etc.

7.1 Lighting objectives The functions of the lighting in spaces adjoining teaching and conferencespaces are:

• To provide for the entrance and exit of the users, bearing in mind thatmany people may need to get in and out in a short time.

• To put users, as they approach, in an appropriate frame of mind for theactivity in which they are about to take part.

• In some cases, especially ante-rooms, to provide a social atmosphere(such spaces are often used as tea and coffee spaces).

• In some cases, to indicate to visitors the route they should take to reachtheir destination, e.g. the lecture theatre in a museum. In other cases,

e.g. a suite of teaching rooms in a college, this may not be appropriate.

The lighting of an adjoining space should therefore be designed in parallel

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Table 7.1 Checklist - Adjoining spaces

8 Emergency lighting

In all of the premises covered by this Guide, large numbers of people willgather together. It is therefore necessary to provide emergency lighting,which is defined as lighting that will enable people to see their way out of a

building in the event of the normal lighting failing. It must be stressed thatit is not the function of emergency lighting to enable normal activities tocontinue within a building if the main power supply should fail; such lightingis referred to as standby lighting and is not normally provided in educationaland conference premises.

In many buildings these may be an actual legal obligation to provideemergency lighting. The Fire Precautions Act (10) and the Health and Safetyat Work etc. Act (11) require adequate means of escape in all places of work

and public resort. Emergency lighting is an essential part of this requirementand should be provided in all areas where there is insufficient natural lightingat all times that persons are on the premises. BS5266 Code of practice for theemergency lighting of premises (12) lays down minimum standards for theindication and illumination of escape routes in the event of failure of normalsupply. The role of this emergency lighting is to reveal a safe passageway,fire alarm call points, fire fighting equipment, escape signs and any permanenthazards along the escape route.

Advice on the design of emergency lighting installation is given in Technical Memoranda TM12: Emergency lighting

(13). When new buildings are planned,

consideration should be given to the needs of emergency lighting in the earlystages of design. If any alteration is planned in the lighting of existing

buildings, care should be taken to see that emergency lighting requirementscontinue to be met. In the case of other buildings it is a

conference lighting

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