Architectural Lighting Design E-Book

Admir Jukanovic

• Herausgeber: Crowood
• Kategorie: Geisteswissenschaft
• Sprache: Englisch

Veröffentlichungsjahr: 2018

Beschreibung

Where do you start if you want to light an interior space? What is the best colour temperature for your design scheme? What do you need to consider when choosing LED lamps and luminaires? Architectural Lighting Design answers these questions and more in a comprehensive introduction to the design, application and techniques of lighting interior spaces. Using real examples of successful lighting schemes, experienced designer Admir Jukanovic explains the fundamentals of lamps and luminaires, and how to meet the requirements of a design brief. Topics include treatments and techniques for lighting designs; tips for understanding the deliverables and fulfilling brief; the five project phases, from concept to commission and the common pitfalls to avoid when using artificial lighting in architecture.

Leseprobe

ArchitecturalLighting Design

A PRACTICAL GUIDE

ArchitecturalLighting Design

A PRACTICAL GUIDE

Admir Jukanović

THE CROWOOD PRESS

First published in 2018 by

The Crowood Press Ltd

Ramsbury, Marlborough

Wiltshire SN8 2HR

www.crowood.com

This e-book first published in 2018

© Admir Jukanovic 2018

All rights reserved. This e-book is copyright material and must not be copied, reproduced, transferred, distributed, leased, licensed or publicly performed or used in any way except as specifically permitted in writing by the publishers, as allowed under the terms and conditions under which it was purchased or as strictly permitted by applicable copyright law. Any unauthorised distribution or use of this text may be a direct infringement of the author’s and publisher’s rights, and those responsible may be liable in law accordingly.

British Library Cataloguing-in-Publication Data

A catalogue record for this book is available from the British Library.

ISBN 978 1 78500 458 2

Contents

Introduction

Chapter 1 The Basics – Lamps

Chapter 2 Luminaires

Chapter 3 Treatments and Techniques

Chapter 4 Understanding the Project – What Questions to Ask

Chapter 5 The Services and Deliverables

Chapter 6 Common Pitfalls

Appendix – A Checklist of Potential Pitfalls

Index

Introduction

Beauty is revealed by light and the delicate play between light, shade and colour. When correctly applied, good artificial architectural lighting has a natural quality that instinctively feels right and helps us to feel good. The need for lighting design rather than lighting that fulfils the regulatory and statutory requirements began half a century ago.

ARCHITECTURAL LIGHTING DESIGN BEGAN to get noticed in the 1950s in the United States and later spilled over to the UK and some other European countries. Lighting design is a fairly new job description. There aren’t many courses to enroll in if one wants to become a lighting designer. Not being able to influence what is taught in the few courses available leads many lighting design consultancies to educate their own future lighting designers. In fact, some consultancies prefer to foster their own talent to assure a good-quality basic training paired with a design philosophy that matches the company’s philosophy. Many lighting designers have either a design or architecture background and received their basic education and finishing at a consultancy. I myself am a product of this process and all I know has either been learned on the job or self-taught. Now, I have started to share my knowledge and experience with the newcomers arriving at our consultancy.

This book is aimed at all new starters and the interested alike, and will hopefully become a foundation for architects and future lighting designers. Therefore, this book covers the technical aspects of lighting design as much as design-related features. The structure of the book allows a person not familiar with lighting to get a step-by-step introduction to lighting design. It starts with the basics of lamps and luminaires and the lighting tools available. These three first chapters form the technical groundwork of the book. The fourth chapter is the core of the book and explores the key aspects of lighting design, while the fifth chapter demonstrates what deliverables are expected and how to present them. All explanations are backed up by images and diagrams throughout, though most of the architectural images used in this book have been saved for the final chapter. Rather than finishing with case studies of successfully executed jobs, this book closes with pitfalls, as a successful lighting design scheme depends as much on well-executed details and the avoidance of pitfalls as it does on its overarching concept.

This book will not teach you how to be creative and come up with a great lighting concept, but it does offer the tools and advice to create the structure of knowledge and the safety net you undoubtedly will need to do so.

Chapter 1

THE BASICS – LAMPS

BEFORE GETTING INTO THE BASIS OF artificial lighting, the so-called light source, let’s take a brief look at its terminology. What most people don’t know is that what normal people call a bulb is actually a lamp. Mind you, most of the lamps used today do not come in bulbous shapes anymore but are available in various shapes from the tube to the sphere to the cone. Each light source, whether fluorescent, gas-discharge, LED or incandescent, should ideally be called a lamp.

Fig. 1.01 Different types of lamps.

THE LUMINAIRE

To make things more confusing, people not involved in the lighting industry call a light fixture a lamp. When the oil light fixture got replaced by the safer and brighter gas light fixture and then by the safer and brighter electric incandescent light fixture people understandably decided to call it ‘the lamp’ only. In the lighting industry, however, it is still called the light fixture, light fitting or, more elegantly, the luminaire.

Fig. 1.02 A luminaire by the Artemide.

ALL ABOUT EFFICIENCY

Since the invention of the practical electric incandescent lamp by Swan/Edison in 1878/1879, many improvements have taken place. Lamps have either become more efficient or smaller or have a greater life expectancy. However, the improvement of one aspect of the light source doesn’t mean all the attributes have improved. Whilst some lamps improved in life expectancy and efficiency they lost the capacity to be dimmed. Being able to differentiate between the various parameters of each lamp is crucial when working and designing with light.

One of the most important parameters defining the quality of a lamp is its efficiency. Due to the introduction of the electric meter reader, rising electricity prices and increased ecological awareness the efficiency of lamps has become ever more important. The following explanations should help you to understand what defines the efficiency of a light source.

Wattage

We all know that a watt is a power unit and that more wattage means more power for a light source. So, if one wants a brighter light source, knowing the wattage helps to quantify the light output. The light output increases with an increasing wattage. Therefore, a higher wattage seems to be better and should give more light. This, however, applies only when comparing apples to apples. For example, a 35w metal halide lamp produces more light than a 100w incandescent lamp. Knowing the wattage does not allow us to compare the light quantity of various light sources. We need to take a look at another aspect of the light source as well.

Luminous intensity: (areal intensity)

The intensity of a light is best defined by its luminous intensity. Luminous intensity of emitted light is measured in candela. This reveals the concentration of emitted light per second by a light source shining in one direction and at a solid angle. It takes into consideration only the wave spectrum our eyes are capable of processing.

Fig. 1.03 Luminous intensity – areal intensity.

Lumens: (overall intensity)

The second parameter is the lumens output. If one wants to know how much light a lamp emits, one has to know how much lumen it produces. Lumen is a measure for all the visible light emitted by a light source. These figures are very useful as they give us an indication of how much light a lamp emits in total or what overall output one can expect from a lamp. It is still not enough to evaluate the efficiency of a light source, however, as it doesn’t include the energy or the wattage used in achieving this output.

Fig. 1.04 Luminous intensity – overall intensity.

Luminous efficacy

Here the luminous efficacy comes in as it defines the lumens per watt a light source emits. This is probably the best way to compare apples to oranges as it reduces every light source to a basic efficacy ratio. Now we can compare the efficacy of any light source. We can compare the light output of an incandescent lamp of 16lm/w with a state-of-the-art LED light source producing 100lm/w.

Fig. 1.05 Luminous efficacy.

ALL ABOUT QUALITY

Despite its many appealing features, one cannot say that an LED light is in all aspects superior to an incandescent light source. The light produced by incandescent lamps is, in most cases, perceived as ‘more natural’ and these lamps reproduce colours with more depth and intensity than other light sources. As a matter of fact, the incandescent lamp acts together with daylight as our benchmark when it comes to natural light colour reproduction. There are a few LED modules that can mimic and exceed incandescent lamps in CRI.

Colour Rendition Index (CRI)

Until the introduction of replacements for the incandescent lamp we didn’t have to pay attention to colour rendition. The incandescent light source produced a light perceived as warm and natural. The colours lit by the incandescent lamp appeared true when compared with a natural light. Shortly after the first incandescent replacements were introduced, people started to realize that the quality of the light did not match Edison’s/Swan’s original or natural light. The colours lit by the replacements appeared duller and flatter. The best way to visualize and understand this is to compare the light that different lamps produce by analysing their emitted light spectrum. While incandescent light, when split by a prism, produces a continuous spectrum of light colours, fluorescent light is able to produce only an interrupted, incomplete light colour spectrum. Its colour rendition is compromised accordingly as it lacks elements of the light spectrum that allow it to reveal colour accurately.

Fig. 1.06a Natural light or an artificial light with a CRI 100 refracted by a prism.

Fig. 1.06b Light diffraction with a 35mm (1.4in) slide to evaluate the colour rendition of a light source.

The colour rendition of a fluorescent lamp or high-pressure sodium light sources is low when compared to the ideal natural light. The Colour Rendition Index (CRI) has been introduced so we can measure the capacity of a light source to display colours faithfully when compared to a natural or ideal light source. The ideal or best CRI is 100 and is reproduced by natural light, incandescent lamps or halogen lamps. All trustworthy manufacturers are able to present the CRI of their product. If this is not the case, one should refrain from specifying the light source. There are, however, various methods to check a light source’s colour renditions. The numeric CRI value can’t be verified like this, but this kind of checking nevertheless allows for a subjective comparison and evaluation.

One could buy an expensive light meter that can provide an accurate colour rendition graph, but the easiest and most cost-effective way to test colour rendition is to consider a lamp with a spectroscope, which one holds against the light’s source.

Light passes through the foil, creating all visible spectral light colours. If it shows all spectral colours, the colour rendition is good while a lower colour rendition will produce gaps in some of the areas. This approach shows the colour wave length the light is lacking but not the effect it has on colours. This can be checked with a colour checker also called a colour rendition chart.

A colour checker allows one to see how colours will look under the light sources they are exposed to. It is a black card board with twenty-four coloured squares mounted onto it. The colour checker contains a representation of colours from real objects, such as skin or foliage to primary, secondary, miscellaneous and greyscale colours.

Fig. 1.07 Colour rendition chart.

If all colours are shown correctly when compared with an ideal light source, the rendition can be considered as good. Originally introduced to verify correct lighting in photography and movie-making it is also increasingly used today by critical lighting professionals as benchmark chart.

Colour temperature

Fig. 1.08 Colour temperature scale.

When entering a DIY shop to try and buy a white paint one realizes quickly that there is no single white on display but a variety of whites. One realizes quickly that the shopping might take a bit longer than anticipated as the decision about which white to paint our walls with is, of course, important to us. The same applies to white light sources. There is no single white light source in a shop display but a variety of white light colours and it is important that the white light one chooses feels right. The colour temperature of white light is measured in kelvins and ranges from the warm 1700K of a candle to the cold bluish 20000K of the arctic sky. Our sun is a great example of the variance of white light. The sun emits in the morning and evening a warm white light, creating visually warm surfaces. The light gets increasingly cold, reaching its peak when the sun is at its highest point in the sky.

Artificial light sources seek to mimic daylight and are available in all colour temperatures. They start from a very warm 2400K and usually end with the cold 6500K. The colour temperature 4000K is perceived as neutral white, neither assignable to the warm spectrum of white light nor to the cold spectrum.

Colour temperature preferences

The preferences towards colour temperature vary from country to country. In northern countries, warm light is generally the preferred choice. A warm light seems more inviting in a region dominated by cold nights and days throughout the years. In southern countries however, the opposite is the case. In a warm climate, a cold light invites you to cool down and refresh and is therefore the generally preferred choice.

Of course, this is not to say that there are not variations across West and East as well as cultural exceptions.

Fig. 1.09 Warm, inviting light, Kakslauttanen Arctic Resort.

Colour temperature and objects

To cast an object or a product in the right light, not only is a good colour rendition important but also the right colour temperature. The appearance of an object changes with the colour temperature it is exposed to. Some colour temperatures are more suitable for some objects than other. This knowledge must be taken in consideration when choosing a lamp. Products like meat profit from more reddish warm light whereas fruits look best in bright neutral daylight. Bread products look best in a warm orange light whereas fish will look fresh and appealing under bright cool light.

The coverage of the exposition area is important. When we buy meat and fish we like to see the entire product. These items usually can’t be touched by us before purchase; therefore, we rely almost completely on our visual senses. We are particularly sensitive when purchasing them and do not appreciate when some parts of the products are left in darkness. Bread, on the other hand, comes daily into our bakeries and we touch it through the packaging to test whether it is soft inside and crispy outside. Here, lighting is allowed to be more dramatic. Partial light is more forgiving, and so should be used in display areas where possible, such as in bakeries where full lighting is not essential.

Fig. 1.10 Colour temperature in relation to products.

Light distribution

When illuminating objects, the distribution chosen is important. Lamps distribute light differently. Fluorescent lamps and LED tubes, for example, generate a diffuse soft light with a big emission surface while incandescent, halogen and metal halide light sources, and their LED counterparts, emit light from a small point, creating strong shadows. In both cases, the distribution is almost 360 degrees but the effect caused is different.

In the early days of artificial lighting, these light sources were either used bare or behind a shade. However, soon, the first light sources would be used with an external reflector, allowing one to guide the light at the angle and in the direction needed. Lamp manufacturers have quickly learned to integrate reflectors and offer various point-light sources with integral reflectors forcing the light into a specific angle. The so-called beam angle is important as it spreads light very precisely, allowing one to illuminate some areas very strongly while leaving others in darkness.

Fig. 1.11 Light distribution of various lamps.

Many luminaires come with reflectors; others, however, allow the usage of lamps with integrated reflectors. This permits one to change the distribution of the light after the luminaire has been installed by simply changing the lamp rather than the entire light fitting.

Dimmability

As the day changes, light intensity changes, and so does our need for artificial light. At home, we would like to use one and the same luminaire to either fill our living room with light or to create a subtle and soft light. In a theatre play, dimming and tuning lights is essential as this allows us to gradually withdraw attention from one side of the stage, moving it slowly to the other. Besides changing the mood, dimming light can serve the cause of saving energy by supplying only the light needed rather than the full amount of light available. This has in most cases the positive side effect of extending the life expectancy of the light source considerably. Not all light sources are dimmable. Some lamp groups allow full dimmability while others cannot be dimmed at all. Lighting designers tend to use dimmable lamp types in interior projects as they allow the change of light scenes and precise light-level adjustment. Dimmability unfortunately has its price. Therefore, choosing when to go for dimmable lamps and when to use only non-dimmable light sources depends often on a project’s budget as much as it depends on the project’s requirements.

Fig. 1.12 Dimmability chart.

Life expectancy

The life expectancy of a light source might not be an issue when replacing a desk light equipped with a low voltage halogen lamp. The price of the replacement lamp is affordable. The desk lamp might be used on average only one hour daily. This means that with an average life expectancy of 2,000 hours it needs replacing every five and a half years. It is usually a very simple process as there are no special tools required and it can be done while sitting on the office chair at home.

The viewpoint changes dramatically when changing lamps in a ten-storey-high atrium or in a huge office building where more than 1,000 lamps are used ten hours daily at three-metre height. The life expectancy of a lamp suddenly becomes one of the prime factors. Life expectancy varies between 2,000 hours and 50,000 hours, and a lighting system is only as good as its weakest link. Besides the lamp, one has to take the ballasts and their operating hours into consideration.

Fig. 1.13 Life expectancy.

The lamp property star

When specifying luminaires and their lamps for a project, one will automatically ask for certain properties of a light source. When choosing a lamp and the light it produces, one usually divides its properties into aesthetic properties and numeric properties.

First, the subjective or aesthetic light quality a lamp delivers is chosen. Colour rendition, colour temperature and the light distribution create what one could call an aesthetic triangle as they define the aesthetic properties of the lamp. On the other hand, elements that are not directly related to the aesthetic perception of the light, like its dimmability, life expectancy and efficiency form the second basic triangle. Together, these triangles form a lamp property star that might help you to ask the right questions when looking for the right lamp for a project.

Fig. 1.14 Lamp property star.

TRADITIONAL LAMP TYPES

We are at an exciting stage in lighting design as we are experiencing a lighting revolution. The LED is able to replace most of the lamps we manufacture today. It is only a matter of time before it will replace all known light sources. What hinders it currently are two key factors: the price and the fact that there are many luminaires out there that still work with the old lamps. The LED manufacturers offer alternatives for these lamps and are able to cover most of the lamp replacements needed for the market. However, it is still worth taking a look at the existing ‘old’ light sources. Why? Well, firstly, we are still in a transition period and it will take some time before all lamps are replaced by LEDs. Secondly, as LED manufacturers are aiming to replace existing lamps, one should understand whether they are really replacing an apple with an apple. A lighting designer should be able to evaluate an LED replacement. To do so, one needs to understand the three main lamp groups, their functions and their attributes.

Incandescent lamps

It all started with the bulb-shaped incandescent lamp so let’s start with it as well. The incandescent lamp is to many people a well-known old companion, first mass produced in its current shape by Thomas Edison in the 1880s. The principle behind it is simple and is based on temperature radiation. A thin, curled, vacuum-sealed carbon filament heats up and starts to emit light when a current is applied. The higher the current, the higher the light emission.

Fig. 1.15 Lamp properties – GLS incandescent lamp.

Soon, inventors all over the world started to look for improvements. Tungsten metal, also known as wolfram, proved to be a superior filament and replaced the carbon filament. The vacuum originally preventing the filament from oxidation got filled with halogen which again improved the performance of the lamps. Mass production and the cheap pricing of incandescent lamps made them spread quickly. They come in all shapes and sizes and became the prime domestic light source throughout the twentieth century. Unfortunately, this method of generating light is inefficient and produces mostly heat. The fragile and thin filament usually stops working after 1,000–2,000 hours and less than 5 per cent of the energy input is transformed into light. Therefore, many countries are now banning common incandescent lamps, also called GLS lamps, from the market. However, we might continue to see tungsten halogen lamps due to their higher efficiency in the years ahead.

Fig. 1.16 Lamp properties – halogen lamp.

Metal halide lamps

While the incandescent lamp emits lights through heat radiation, the metal halide lamp generates light by creating an electric arc. To do so, it requires two electrodes and a mixture of metal halides contained under high pressure. The bright light is generated when the arc vaporizes the halides within the so-called arc tube. The second tube around the arc tube prevents heat loss and is often used to control the emission of UV (ultraviolet) light. High-intensity gas discharge lamps need time to reach their desired light intensity and once turned off require time to cool down and to be able to reignite. Metal halide cannot be dimmed. To run metal halide lamps, one requires an external ballast to provide the needed ignition and to control the current. On the other hand, metal halide lamps do have a good colour rendition and are highly efficient, with a life expectancy of up to 15,000 hours. Therefore, they were widely used in the retail sector and in many public buildings as well as in street lighting and for stadium illumination.

Fig. 1.17 Lamp properties – metal halide lamp.

Fluorescent lamps

Fluorescent lamps are low-pressure gas discharge lamps. They are in effect a glass tube filled predominately with argon and a small quantity of mercury. At each end, they contain coated tungsten filament cathodes that emit electrons when put under current. A high-voltage pulse moves the electrons through the tube creating an argon arc. The arc vaporizes the mercury within the tube, producing UV light. All fluorescent lamps are coated with phosphor that emits visible light once energized by the UV light. The composition of the phosphor defines what colour temperature the light is going to have. Unlike an incandescent lamp and the high-intensity gas discharge lamp, the fluorescent lamp does not get hot. Beside the standard tube-shaped fluorescent lamp, there is the compact fluorescent lamp that is found more frequently in households than its relatives. Unlike the tube-shaped fluorescent lamps that are run with a remote electronic control gear, the compact fluorescent lamps have an integrated control gear that allows them to be used off the shelf and screwed into standard fixtures. Just like the metal halide lamp, the compact fluorescent lamp it is a true workhorse: efficient and with a high life expectancy. Therefore, it can still be found nearly everywhere from office buildings to galleries and in our homes. The CRI is lower than in incandescent and metal halide lamps but it has an impressive efficiency that lies at around 20 per cent. It lasts around 20,000 hours, significantly longer than an incandescent lamp.

Fig. 1.18 Lamp properties – fluorescent lamp.

It also emits less heat; therefore, its surface is touchable. Unfortunately, fluorescent lamps contain highly toxic mercury and require specific waste management as they need to be separated from your general waste.

LAMP CONNECTION METHOD

Lamp types do come in different sizes and shapes. Throughout the decades, different connection methods have developed and become standards. Screw connections are probably the one most known to all of us. E27 and E14 screw sockets hold standard Edison incandescent lamps and haven’t changed since Edison launched the mass production of his ‘light bulb’. They are used in most of our home luminaires and will remain the standard socket despite the decision to phase incandescent lamps out.

Fig. 1.19 Socket requirement for common lamp types.

Newer light sources have had to develop a different fixing method as they differ from incandescent lamps radically in size and shape. Most halogen, fluorescent and metal halide lamps require bi-pin sockets. The bi-pin sockets have to accept only two metal pins. Depending on the lamp shape they are either simply pushed into the connector or are turned into their sockets.

The two pins on each side of the tubular fluorescent lamp, for example, are turned into the sockets. For some time, this was the sole shape and therefore fixing method for a fluorescent light source, until new U- or O-shaped fluorescents demanded a new way of fixing and therefore a new connector type. The development of the compact fluorescent lamp, on the other hand, seeks to adapt the size and shape of the lamp in order to fit into existing widespread E27 and E14 sockets.

This is all driven by a market for longer-lasting and more efficient alternatives to incandescent lamps. The same development can be observed in the new LED market. Either new LED connection methods emerge or the manufacturers enter the huge existing market by creating LED lights that fit into existing sockets.

LIGHT EMITTING DIODE – LED

There is a new kid on the block seeking to replace all existing luminaires and outperform them. LEDs are revolutionizing our industry and are clearly able to supersede existing lamp performance. Due to their compact dimensions, they create new possibilities in luminaire design and allow for greater creativity when designing with light. Before comparing the old versus the new, one should understand the basic principles of the Light Emitting Diode and its origins.

Fig. 1.20 Semi-conductive positive and negative layer separated by a junction.

Function

Unlike the ‘old’ light sources, an LED is based on solid state technology. This means that no delicate filaments and gas are used. It makes the LED extremely robust against vibration and impacts. LEDs are based on diode technology. A diode consists of two semi-conductive materials. P is the positive region and N is negative region, and these are joined by a junction. When a current is applied, electricity can pass in one direction but not the other. Light is emitted when electrons pass the N region towards the P region where they fill the missing electron gaps. While doing so, the electrons fall into a lower energy state, lose energy and emit photons.

History

It took almost 100 years from the discovery of diodes emitting light to our modern LEDs, which are capable of generating white light. As with many inventions, it was an international joint venture where one discovery built on others. It all started in 1907 in the UK where H.J. Round reported light emission when experimenting with the first semiconductor diodes. In 1962, more than half a century later, Nick Holonyak, ‘the father of the light emitting diode’, developed the first LED that generated visible light. These first LEDs emitted light in red only and were initially too expensive to be found in our daily lives. In the 1970s, mass production enabled the spread of seven-digit displays in watches and calculators. It wasn’t until 1995 when Shuji Nakamura and his team developed the bright blue LED, which enabled them to create white light soon after. Shuji received the Nobel Prize for Physics for his discovery. Just as with the fluorescent lamp, the key to generating the right light lies in the second medium called phosphor. Everyone who is familiar with the addition of primary colour of light knows that red and blue light turn into yellow light. Mixing yellow with blue light creates white light. In an LED lamp, the blue light gets transformed into white light when passing through the yellow phosphor layer. The phosphor coating transforms part of the light into yellow light, allowing blue light to pass through unchanged at the same time. The blue and yellow light mix into white light. The thicker the phosphor layer, the more of the blue light gets transformed into yellow light. The light emitted by the LED then appears more yellow and warmer.