External Lighting for Historic Buildings

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External lighting for historic buildings

CONTENTS

1 Introduction 1 10

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2 General considerations

Should the building be lit?Does the entire building need to be lit?Is there a pattern or arrangement which should be featured?

Where can external lights be positioned? Are there any adjoining properties? Is light spilling from the surroundings?

How big and how clean is the building? Are there environmental matters to consider?What is the most suitable light source?How are illumination levels established?Are trials necessary?

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3 Types of lighting

Conventional external lighting schemes Architectural lightingDynamic lighting

4 Types of light sources and levels to use

Lamp DataAvailable lumen intensities and distributions

5 Types of control systems

6 Environment, security and dark skies

Effects on the environment Security Dark skies

7 Installation and maintenance issues

8 Glossary

9 Bibliography

Web-based reference material

10 Useful Addresses

11 Acknowledgments

The information in this publication is based on our current knowledge. Whilst every effort has been made to ensure the accuracy of the advice given, English Heritage does not accept liability for loss or damage arising from the use of this information.This publication is intended as a general guide and should not be used as a substitute for professional advice

The inclusion in this publication of any company, group or individual, or any product or service, should not be regarded as either a recommendation or an endorsement by English Heritage or its agents.

The installation of an external lighting system implies in most cases the fixing of equipment to the fabric of a building. English Heritage seeks to ensure that any works to a historic building do not disturb or destroy historic fabric. In deciding how best to illuminate a building, the principles of minimum intervention and reversibility should be adopted whenever and wherever possible.

FRONT COVER: Image showing a lit building situated along Grey Street, Newcastle

INTRODUCTION

Our historic buildings and monuments are often amazing feats of architecture and engineering. Many have been enhanced and brought to life at night-time with striking and subtle external lighting schemes. Some, however, have produced far more negative results by highlighting flaws and views of the structure never meant to be seen. Just because a building or structure happens to be listed does not mean this is a good enough reason to proceed with external lighting.

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There are a number of matters that should be examined before progressing with a design.The most important of these is the question, ‘Has a real need to install lighting been established?’ The next must be the acceptance that a simply technical approach is useless.

The main objectives of external lighting should be:

● to promote observation and experience of the site against the night sky

● to give the building an added dimension which will enhance its key architectural elements as well as its social and historical significance

● to improve the quality of the nocturnal environment by promoting safety, ie avoidance of trip hazards

● to enhance night-time orientation and use, which could potentially benefit the local economy

Therefore an aesthetic, as well as a technical, approach is essential and will ultimately govern the result. When external lighting is executed with a well-designed and co-ordinated scheme using the correct choice of equipment, the environmental impact, ie light pollution and overspill, can be minimised and the energy efficiency maximised.

1c Subtle external lighting when designed with care and sensitivity can bring added life and scope to some of our most treasured landmarks. It becomes an extension to the architecture, improving the quality of the view and complementing the structure’s shape, colouration and form. It gives an added dynamic by bringing the ‘soul’ back into a place, and can be likened to ‘painting with light’.

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1a Kingston upon Thames Bridge. (Photograph courtesy of Sill Lighting)

1b The Poseidon Fountain,Witley Court,Worcestershire. (EH photo library K971385)

1c Concentration of light on a prime local site.

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GENERAL CONSIDERATIONS

Should the building be lit?

If a real demand for lighting has been established in conjunction with the owners or custodians, then the designer must look to limit the amount of light to that strictly necessary to achieve the aims of the scheme.

Does the entire building need to be lit?

It is rarely necessary to light all the elevations of a building, some parts often being unsuitable or inaccessible for viewing. It is usually better to concentrate on the prime nearby and distant night-time viewpoints. As part of the design process distance, angle and position of the viewer should always be taken into account.

Is there a pattern or arrangement which should be featured?

It is often better to illuminate selected architectural and sculptural features such as pediments, columns, porticos or niches, rather than illuminating the whole building. External lighting to reinforce a building’s patterns can increase the appreciation of architectural details. Crosslighting, uplighting and backlighting should all be considered, although uplighting must be limited and well controlled to avoid light pollution.

Designs can be refined by the use of tight beam control; shutters or baffles can also help reduce night-time light spill. However, the latter solution is rarely acceptable in appearance during the day unless the fittings can be concealed.

This leads to the next question.

2ab Night and day views of Government House in Guernsey. Only the architecturally important sections of the front elevation have been illuminated. (Lighting design by Sutton Vane Associates)

3a Backlighting used at Manchester Crematorium. (Photograph courtesy of Lighting Architecture)

3b Uplighting used to illuminate Central Exchange Buildings, Grainger Town, Newcastle upon Tyne. (Lighting design by Sutton Vane Associates)

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Where can external lights be positioned?

It is essential that all luminaires are inconspicuous, easy to install and maintain, and respectful of the historic fabric. Even though a lighting design may give the desired effect at night, if the floodlights cannot be effectively hidden from view or disguised, the scheme must be rethought.

One solution is to floodlight from a remote position. Luminaires can be positioned on nearby buildings or street furniture.Where there are trees and shrubs it may be possible to disguise lighting poles.

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4 Lighting to emphasise the pattern on a building.

5abc Lights hidden from view in basement or lower pavement areas and how they should be aimed. (Fig 5c courtesy of the Institution of Lighting Engineers)

Are there any adjoining properties? Is light spilling from the surroundings?

Neighbouring properties and the surrounding area must be taken into account. In rural areas, with lower ambient light levels with which to compete, less light will be needed to floodlight a building.This is often overlooked in lighting scheme designs.This will reduce both the initial outlay costs and ongoing energy consumption.

How big and how clean is the building?

As well as the existing ambient lighting, the reflectivity of the building surfaces must be taken into account.This will be affected by the colour of the building materials, and how clean they are.The more reflective a building, the fewer luminaires will be needed and the less powerful they will need to be.

Are there environmental matters to consider?

Lighting can affect some animals (for example bats and owls) that make historic buildings their home. Some animals and their habitats are protected by law.Where proposed external lighting may affect such animals an impact assessment will need to be made, taking into account breeding, hibernation and points of egress and ingress. As well as the increase in light levels, the effects of installation and maintenance must also be taken into account.

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6a Remote light on a pole hidden by foliage.

6bc Remote light disguised by a street lantern. (6b Lighting design by Sutton Vane Associates)

7 Wildlife considerations.

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What is the most suitable light source?

The choice of light source must take into account the colour and reflectivity of the building surfaces, the desired colour rendering, the colour or operating temperature of the lamps, and their effect on the building materials.

Street lighting designers have begun to move away from high-pressure sodium (SON) lamps to metal halide (HIT) lamps, which is to say from warmer, red tones to cooler, blue tones of the colour spectrum. When choosing floodlamps the designer must take into account both the colour and the level of the local street lighting.

To increase impact an interesting effect can usually be achieved by using a lamp of a type different to that being used for the existing lighting, and this can also reduce the necessary number of luminaires and their power rating. If there is any doubt as to which lamp should be chosen, then a small field trial will usually be enough to determine the correct type.

How are illumination levels established?

The following publications provide standards and guidance:

● British Standards 1996 Road Lighting. Code of Practice for Lighting for Urban Centres and Public Amenity Areas (British Standard BS 5489-9:1996). With simple examples of the calculation process

● Chartered Institution of Building Services Engineers (CIBSE) 1992 The Outdoor Environment (Lighting Guide LG6). London:The Chartered Institution of Building Services Engineers. Includes various lighting techniques

● International Commission on Illumination (CIE) 1993 Guide for Floodlighting (Publication 94).Vienna: International Commission on Illumination

● Electrical Contractors Association (ECA) Decorative Exterior Lighting of Churches. London: Electrical Contractors Association. Includes procedures for defining the most suitable type of lamp and location based upon the type of building material and its condition

● Institution of Lighting Engineers (ILE) 1994 Lighting and Crime. Rugby: Institution of Lighting Engineers

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8a Soft lighting of a rural building.

8b Muncaster Castle, Cumbria. (Lighting design by Sutton Vane Associates; photograph by Brian Sherwin)

Are trials necessary?

The technicalities of colour rendering can be difficult to visualise, so it is often very useful to arrange a site demonstration of the options being considered. Photographs taken during the trial can be very useful when applying for planning permission.

With general historic environment and building stock, consultation of the government’s Planning Policy Guidance Notes (PPGs) – Planning Policy Guidance 15 (PPG 1994) in particular – and their replacements, Planning Policy Statements (PPSs), should be made.These documents provide a framework and a useful reference to the overall principles and requirements of the planning system. In addition a proposal to externally light a building may need planning permission under the Town and Country Planning Act 1990, so early involvement of the local planning authority is recommended as many aspects of the design have the potential to be affected.

When the building in question is a church that the parish wishes to light, it is often worthwhile experimenting to try and resolve as many problems as possible before approaching the Diocesan Advisory Committee.The committee will be concerned with all implications of the design, including the financial costs (capital, running and maintenance).

Where any historic property is within the environs of an airport, development restrictions can apply, especially if the building comes within the airport’s public safety zone, in which case additional early consultation will be required.

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9 All Saints Church, Newcastle upon Tyne. A lighting scheme employing metal halide lamps against a background of high-pressure sodium lighting. (Lighting design by Sutton Vane Associates)

10 Wide wash of light onto a building.

11ab Remote lighting locations using street furniture or other buildings.

11c Light mounted on a lamp-post; compare the cluttered effect here with Fig 6b. (Photograph courtesy of Sutton Vane Associates)

12 Dynamic lighting of The Monument, City of London.

13ab Illumination of selected elements of buildings.

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TYPES OF LIGHTING

We can break down most external lighting into three basic types, each of which presents its own problems.

Conventional external lighting schemes

These schemes use large-wattage projectors, to give a wide wash of light.

Conventional external lighting schemes are often awkward because to get a good distribution, light fixtures have to be located away from the building and positioned so that the architectural features look as they would in daylight. This means leaving space in front of the building, which in turn means that the fittings will have to be very carefully sited if they are not to appear obtrusive to people entering and leaving the building.This arrangement can be successful for major buildings but is less suitable in smaller, more intimate locations, where fittings may have to be disguised by being buried, placed in an enclosure or located on neighbouring street furniture or buildings.

Architectural lighting

This option uses small, discreet lighting fixtures, mostly located on the façade, to light details.

Architectural and detail lighting can take many forms, from mini-floodlights to highly efficient light-emitting diode (LED) linear fittings. As fittings are often located on the building itself, installation must be handled carefully to avoid damaging the fabric. Architectural lighting is not intended to make the building appear as it does during the day, but instead to offer a very different and selective view.

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Dynamic lighting

This choice makes use of theatre-style lighting fixtures to produce coloured light, moving patterns or projected images.

Dynamic lighting has limited use, but where the building is very plain and unadorned it can be pleasing for special occasions and celebrations. I should be stressed, however, that a permanent dynamic display can quickly become boring.

It is better to employ dynamic lighting for short periods of time; good example are the pink floodlighting of London’s Wellington Arch for Breast Cancer Awareness Month in 2001 (see Fig 15a) and its subsequent illumination with images of falling poppies for the 80th anniversary of the Royal British Legion. At Christmas time, the Amiens Cathedral in France has a 45-minute light show which colours the façade as it would have been in medieval times, painted and gilded, only this time with light.

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14 Coloured lighting of a building.

15a Wellington Arch, London, for Breast Cancer Awareness Month, 2001. (EH photo library K010791)

15b St Paul’s Cathedral for World Aids Day, 2002. (Lighting design by Sutton Vane Associates)

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TYPES OF LIGHT SOURCES AND LEVELS TO USE

Listed below are the most commonly used light sources for external lighting.

Lamp data

Lamp type Colour appearance Colour Rendering Efficiency Rated life (hours) Index Ra (sun=100) (lumens/watt)

Tubular fluorescent White 50–90 Good 15–70 Medium 6,000–10,000.

Compact fluorescent White 80 Good 25–80 Medium 10,000

Metal halide, warm White 65–80 Good 50–95 High 6,000–20,000 colour (also used in fibre-optic systems)

Metal halide, cool White 65–90 Good 50–105 High 6,000–20,000 colour (also used in fibre-optic systems)

High-pressure mercury White 40–50 Poor 25–55 Medium 12,000–24,000

High-pressure sodium Yellow 25–60 Poor–medium 55–130 High 14,000–24,000

Low-pressure sodium Orange Not applicable 70–180 High 16,000 (monochromatic)

Light-emitting diodes White (also 70 White Good 7–10 Poor 50,000–70,000 (but can (in array form) blue, amber, (although colour varies at present but be limited by driver life

green and red) between manufacturing improving to 20,000–50,000) batches)

CDM (ceramic White 80–90 Good 70–95 High 6,000–9,000 discharge metal halide)

Note: tungsten and tungsten halogen lamps have been excluded here: although these have excellent colour rendering, lamp lives and efficiencies are very poor.

Available lumen intensities and distributions

Type of illumination Peak intensity Light distribution Comments (lumens)

Symmetrical beam 1000–2000 Beam width Popular due to low initial costs, but little (discharge lamps) real optical control

Symmetrical ‘projector’ 200–30,000 Beam width A useful tool if carefully applied beam

Simple asymmetric 800–3,000 Beam width Popular due to light weight beam

Asymmetric beam with 700–800 Beam width Gaining popularity due to good control horizontal cut-off of upward light

Bulkhead lights 150 Light distribution Very wasteful unless used in confined space

TYPES OF CONTROL SYSTEMS

The control of an external lighting system does not necessarily require anything more complicated than a simple time switch or a photoelectric cell. Many schemes only operate for a few hours of darkness (for example until 23.00) to prevent unnecessary energy use. Electricity bills are kept low, and the lighting causes much less interference with flora and fauna. Astronomers also benefit from the reduced light pollution.

Round-pattern time switches (as they are often known) come in a variety of ratings and types. Most provide the user with on–off operation which tracks sunset and sunrise times throughout the year, without the need to sense light levels. An added facility allows the user to select a fixed ‘off ’ time – say between 20.30 and 01.00 – and a fixed ‘on’ time. Switches can be provided with a reserve battery, so that power outages do not affect operation.

Round-pattern switches give greater control than photo-sensing devices, which must rely on the level of natural light to operate, usually coming on at dusk and switching off at dawn. On dark and cloudy days photoelectric switches would be activated unnecessarily.

Time clocks can be retro-fitted as surface-mounted units, or designed to be DIN rail – or panel-mounted to suit the site.They are provided with openings and seals for security to prevent possible tampering with the settings.

If more sophisticated operation is required, there are proprietary control systems available, but these can be expensive. For most straightforward external lighting schemes, complex systems are unnecessary.

ENVIRONMENT, SECURITY AND DARK SKIES

This section looks in more detail at some of the issues mentioned previously. Environment, security and dark skies (light pollution) are all important issues, each of concern to different interest groups.

Effects on the environment

External lighting can be extremely disturbing to a variety of plants and animals. Excessive light can have a dramatic impact on the lives of nocturnal species such as bats, frogs, lizards and birds by confusing their circadian rhythms

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16 Line drawings showing types of illumination

17 Useful light, spill light and light trespass. (Diagram courtesy of the Institution of Lighting Engineers)

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(natural patterns of living and breeding). Light can also affect the feeding habitats of nocturnal hunting birds (such as owls) and endanger other birds by disturbing their sleep patterns (a false sunrise which confuses them into singing).

As well as animals, trees and nocturnal insects are also affected. Normal seasonal variations may be disturbed, affecting their interdependency and associated ecosystems. Any reduction in numbers of insects such as moths reduces the food supply of higher birds and animals.

Security

‘More light equals less crime’ is often cited as a reason for external lighting, but there is little hard evidence to support this statement. Despite the popularity of external lighting, crime rates have soared and published Home Office statistical evidence indicates that the presence or absence of light is of little or no importance.The fear of crime can certainly be alleviated with good external lighting, but poorly positioned or misdirected lights can dazzle passers-by and create deeply shadowed areas which hide criminal and anti-social activity.

Well-positioned luminaires will do more to deter criminals than over-lighting. Passive infra-red sensors can give an element of surprise to deter intruders outside the normal operating times of the lighting system.

Dark skies

Artificial lighting has enabled us to do much more during the hours of darkness, but this freedom comes at a price. ‘Light pollution’ is another term for sky glow, the brightening of the night sky caused by dust and aerosol particles of water in the air, which scatter any artificial light.This light comes from wasteful all-night shop advertising and display illumination, and from poor external lighting schemes.

Light pollution prevents much of the population from being able to enjoy the night sky. Sky glow now pollutes nearly all of Britain’s night skies, interfering with professional as well as amateur sky-gazers.

Simple spillage from a badly designed external lighting scheme can cause a major nuisance to others, for example by trespassing into a window and keeping occupants awake.This is in addition to the wasted electricity and its contribution to emissions of greenhouse gases.

However it is not sky-gazers who are responsible for most of the work that has been carried out to reduce light pollution. It is, in the main, down to conservationists, individual residents and local communities.

INSTALLATION AND MAINTENANCE ISSUES

Care in the installation of external lighting is doubly important when it is actually fixed to the building. Such an installation may require listed-building consent.Without thoughtful consideration, light fittings may not only disfigure the façade but their installation may also leave permanent scars on the fabric.

The location of any luminaire should always take into consideration the material onto which it is going to be fixed.To avoid unnecessary destruction, fixings should be drilled into joints rather than into stone and brick.Where this is not feasible, pattresses should be used.

Maintenance is also important; without it the output and safety of the final installation will be seriously jeopardized. However, it is too often viewed as an unnecessary expenditure and neglected. Neglect will inevitably result in system failure, and is uneconomic in the long run. Lighting maintenance should be scheduled into the building’s repair and upkeep. Regular inspections should be made (generally every 3–6 months) during which fittings are checked and cleaned and any faulty luminaires and lamps replaced. Reactive maintenance should be kept to a minimum where possible.

Maintenance is less likely to be regular if access is difficult and expensive. If special equipment or personnel are needed to reach the light fittings, even replacing lamps or cleaning will be prohibitive. However, ease of maintenance may need to be reconciled with the need to hide or disguise the luminaires.

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GLOSSARY

Column A pillar consisting of a base, a shaft and a capital, used to support or adorn a building.

Colour (of lamps) This usually refers to a range from ‘warm’ (reddish) white to ‘cool’ (bluish) white, linked to the operating temperature of the lamp: the higher the operating temperature, the ‘cooler’ the colour.

Colour Rendering Index (Ra) The quantitative index – Ra, used to score the ability of a light source to render colours of surfaces accurately. For example Ra > 90 = accurate colour matching, Ra < 40 = marked distortion of colour.

Colour spectrum (also known as the visible spectrum) The portion of the electromagnetic spectrum that is visible to (ie detectable by) the human eye.

DIN rail (also known as Top-hat rail) A standardised, 35mm-wide metal rail with a hat-shaped cross section, used commonly for mounting circuit breakers.

Light-emitting diode (LED) A semiconductor device that emits light when a voltage is applied across it.The colour of the light depends on the semiconductor material used.

Lumen The SI unit for luminous flux, a measure of the perceived intensity of light.

Luminaire A light fitting used to create artificial lighting or illumination in architecture.

Operating temperature (See Colour)

Niche A recess in a wall for a statue, vase etc.

Pattress A surface box or plate (in any shape to suit), with fixing holes positioned to line up with architectural features, allowing the fixing of a luminaire without permanent damage to the historic fabric

Pediment A triangular element surmounting a portico, doorway or window

Portico A colonnade (roof supported by columns), or a porch with columns.

Projector A fitting capable of throwing a beam of light over relatively long distances.

Reflectivity The reflectance of a material, ie the ratio of reflected to incident (arriving) light intensity, at its surface. Reflectance can be specular (‘shiny’), diffuse or a combination of the two.

Shutter, baffle An adjustable device attached to a light fitting to eliminate light spillage and prevent glare.This often takes the form of a screen, panel or louvre.

BIBLIOGRAPHY

Atkins, Stephen 1991 The Influence of Street Lighting onCrime and Fear of Crime (Crime Prevention Unit paper No28). London: Home Office Crime Prevention Unit

British Standards 1996 Road Lighting. Code of Practice forLighting for Urban Centres and Public Amenity Areas (BritishStandard BS 5489-9:1996)

Chartered Institution of Building Services Engineers (CIBSE)1992 The Outdoor Environment (Lighting Guide LG6). London:The Chartered Institution of Building Services Engineers

Chartered Institution of Building Services Engineers (CIBSE)2002 Code for Lighting. Oxford:Butterworth-Heinemann

Chartered Institution of Building Services Engineers (CIBSE)2003 Environmental Considerations for External Lighting(Fact File No 7, Revision 1). London: CIBSE

Diocese of Chelmsford 2000 Church Floodlighting:Guidelines to Assist Parishes. Chelmsford: Diocesan Office

Electrical Contractors Association (ECA) Decorative ExteriorLighting of Churches. London: Electrical ContractorsAssociation

Electrical Contractors Association (ECA) Guidance forElectrical Contractors on Procedures Leading to theInstallation of Church Floodlighting (Ref P4169608). London:Electrical Contractors Association

English Heritage 2000 Streets for All. London:English Heritage

English Nature 2004 Bat Mitigation Guidelines:WorkingToday for Nature Tomorrow (Ref IN13.6). Peterborough:English Nature

Figueiredo, Peter de 2001 ‘The Waldram Lecture 2000:The role of lighting in the renaissance of historic urban areas’.Lighting Journal March/April 2001, 12–17

Institution of Lighting Engineers (ILE) 1994 Lighting andCrime. Rugby: Institution of Lighting Engineers

International Commission on Illumination (CIE) 1993 Guidefor Floodlighting (Publication 94).Vienna: InternationalCommission on Illumination

Jay, Peter and Crawforth, Bill 2001 Church Lighting. London:Church House Publishing

PPG 1994 Planning Policy Guidance 15: Planning and theHistoric Environment. London:The Stationery Office

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Paterson, James and Mackness, Malcolm 2000 ‘How to do it No 4: Church floodlighting’. Lighting Journal May/June 2000, 10–11

Ramsay, Malcolm 1991 The Effect of Better Street Lighting on Crime and Fear : A Review (Crime Prevention Unit paper No 29). London: Home Office Crime Prevention Unit

Web-based reference material

Building Conservation www.buildingconservation.com

LightPollution.org www.lightpollution.org.uk

Church Care (Church of England) www.churchcare.co.uk

USEFUL ADDRESSES

Catholic Bishops’ Conference of England and Wales 39 Eccleston Square London SW1V 1BX Tel: 020 7630 8220 www.catholic-ew.org.uk

The Chartered Institution of Building Services Engineers 222 Balham High Road Balham London SW12 9BS Tel: 020 8675 5211 www.cibse.org

The Church of England National Church Institutions Administrative Centre Church House Great Smith Street Westminster London SW1P 3AZ Tel: 020 7898 1000 www.cofe.anglican.org

Electrical Contractors Association ESCA House 34 Palace Road London W2 4HY Tel: 020 7221 7344 www.eca.co.uk

English Heritage 1 Waterhouse Square 138–142 Holborn London EC1N 2ST Tel: 020 7973 3000 www.english-heritage.org.uk

Institution of Lighting Engineers Regent House Regent Place Rugby CV21 2PN Tel: 01788 576492 www.ile.org.uk

Natural England (Incorporating English Nature, the Countryside Agency and the Rural Development Service) Northminster House Peterborough PE1 1UA Tel: 0845 600 3078 www.naturalengland.org.uk

ACKNOWLEDGEMENTS

English Heritage would like to acknowledge the help of the following people in the production of this guide:

Alan Anderson, Lighting Architecture

Robert Bohannon, Sill Lighting UK

David Coatham, Institution of Lighting Engineers

Javis Gurr, English Heritage photo library

Steve Newbold, Electrical Contractors Association

Graham Smith, CES

Mark Sutton Vane, Sutton Vane Associates

Text by Geraldine O’Farrell, English Heritage Building services Engineering and Safety Team (BEST)

Figures 1c, 4, 5a, 5b, 6a, 7, 8a, 10, 11a, 11b, 12, 13a, 13b, 14 and 16 by Judith Dobie, Centre for Archaeology, English Heritage

Edited by John King

Design and Production by Creative Services, English Heritage, 04/07

Printed by Vitesse (1000)

Product code 51330

April 2007

BACK COVER: Hoover Building at night, Perrivale, London 13

For copies of this leaflet, please contact English Heritage Customer Services Department on 0870 333 1181 or email customers@english-heritage.org.uk. Published by English Heritage, April 2007. Product Code 51330. Copies are also available on www.english-heritage.org.uk and www.helm.org.uk. Printed on recycled paper containing 75% post-consumer waste.

HELM HISTORIC ENVIRONMENT LOCAL MANAGEMENT www.helm.org.uk