A study of optical properties of various materials as a tool in the process for designing a luminaire

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IN

DEGREE PROJECT ARCHITECTURE, SECOND CYCLE, 15 CREDITS

,

STOCKHOLM SWEDEN 2021

A study of optical properties of various materials as a tool in the process for designing a luminaire

KAJSA GRAHN

KTH ROYAL INSTITUTE OF TECHNOLOGY

SCHOOL OF ARCHITECTURE AND THE BUILT ENVIRONMENT

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Royal Institute of Technology, School of Architecture and the Built Environment Master’s Program in Architecture Lighting Design 2020/2021

Master thesis Title

A study of optical properties of various materials as a tool in the process for designing a luminaire Author

Kajsa Grahn Tutor

Rodrigo Muro Course responsible Isabel Dominguez Examinator Ute Besenecker Course code AF270X

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Abstract

Overlooking the important role materials, in relation to light, have in interior design and architecture is not so uncommon. However, materials are not only important for understanding light in architecture, but also in product design since all objects within a space contribute to its visual character and spatial appearance. This study investigates differences in optical properties of a selection of materials often found in Scandinavian domestic environments. It also explores and discusses the main question of how, in the process of designing a luminaire, product and lighting designers could make use of the visual quality differences between the selected materials, and when put in a spatial context how their properties can be used as a tool to create different lighting scenarios.

In order to answer the main question, the study applied a practical approach including a small scale and full scale laboratory, in which the investigation was based on testing and experimenting with light and material and where qualitative and quantitative aspects were observed, measured, and consolidated.

Abstract

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Table of content

1. Introduction 4

2. Background 5

2.1 How we perceive objects and color 5

2.2 Optical properties of materials 6

2.3 Materials used traditionally for luminaries 8

2.4 Material selection taking sustainability into consideration 10

3. Methodology 11

3.1. Limitations 11

3.2 Literature review 12

3.3 Small scale visual laboratory - intentions 12

3.3.1 Selection of space 12

3.3.2 Selection of light source 13

3.3.3 Selection of materials 13

3.3.4 Qualitative measurements 16

3.3.4.1 Light levels, CCT and CRI 16

3.3.5 Qualitative measurements 17

3.3.5.1 V/P analysis 17

3.3.5.2 Lightness meter 18

3.3.5.3 Own impressions and observation 18

3.3.5.4 Survey 19

3.4 Full scale testing - intentions 20

3.4.1 Set up of full scale testing 20

3.4.2 Selection of light sources 21

3.4.3 Mock-ups 21

3.4.4 Own impressions and observation 21

4. Results 23

4.1 Small scale visual laboratory 23

4.1.1 Spectrometer 23

4.1.2 Lightnessmeter 29

4.1.3 V/P analysis 30

4.1.4 Own impressions and observation 30

4.1.5 Survey 31

4.2.1 Full scale testing mock-ups 32

4.2.2 Own impressions and observations 35

5. Discussion 37

5.1 Using an experiment-based approach in the process for designing a luminaire 37

5.2 The human perception 38

5.3 Suggested design/concept of a luminaire 39

6. Conclusion 41

7. References 42

8. Appendix 44

6 7 7 8 11 13 14 14 15 15 15 16 16 19 19 20 20 21 21 22 23 23 24 24 24 26 26 31 32 32 33 34 43 44 44 45 46 48 49 51

Table of content

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1. Introduction

Starting from a perceptual point of view, the focus of this master’s thesis is to get a deeper knowledge of how light combined with different materials, visually could affect space and atmosphere. The main investigation question for the paper is to understand how materials with different optical properties interact with light and further how lighting designers could make use of the visual differences of each material, to create different lighting effects based purely on the characteristics of the material itself.

“Light and materials are inseparably connected, indeed they actually determine each other:

neither is visible to the human eye until the two come together. Materials are key to understanding light in architecture because they directly affect the quantity and the quality of the light. Two qualities of materials – their finish and their color – are most important in this regard. Specular materials, such as glossy finishes, reflect light as a mirror does, which can result in reflected images of the light source being visible “on” the surface. Matte surfaces, such as natural stone, wood, and plaster, reflect light diffusely equally in all directions. Of the three aspects of color – hue, value, and intensity – value is the one that determines how much light is absorbed and how much is reflected. A change in

materials can alter the feeling of a room and the level of illumination as well.” (Millet, 1996).

The material of the luminare could either mute or emphasize the light, as described by Millet above.

Further, the shape of the luminaire supports the distribution and direction of the light. The light source and the luminare are in constant relation to each other. The material and shape of the luminaire affects the character of the light, at the same time the quality of the light influences the visual image of the object itself. The qualities of the luminaire contribute to the visual appearance of the space that it is put in, as well as the spatial condition affects the appearance of the luminaire itself. These factors together could contribute to create certain atmospheres or to provoke feelings.

“Nowadays, technology, particularly the LED, allows us to design any kind of lamp, and people are more focused on the light itself, what we call the ‘architecture of light’. What is important is more than just designing the lamp itself.” (Fukasawa, 2020).

Inspired by the industrial designer Fukasawa, the approach to the project is to use light as the origin for the process of designing a luminaire. This included letting the desired light decide what material and shape to apply for the luminaire. By going from a strict, small scale laboratory to a full scale study the outcome of the thesis will result in a set of mock-ups for a luminarie, with the expectation to work as a basis for further development of the design. The intended context of the investigation, and for the set of mock-ups, is a domestic environment. The context reflects the range of selected and studied materials in the paper, focusing on materials often found in Scandinavian homes. The main target of the investigation is ambient lighting, with the function to provide indirect light reflected from material samples. The focused typology of the mock-ups departs from table lamps and wall lamps.

1. Introduction

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2. Background

Before going into the optical properties of different materials, the background part of the study includes research of how visual perception relates to light, color and objects. Further, it explains the main interaction processes between light and material. It also exemplifies what materials traditionally have been used for luminaries, as well as highlights sustainable considerations when selecting material in the process of designing a luminaire.

2.1 How we perceive objects and color

The sensation of how we perceive the environment is caused by the visual process in the viewer’s eyes which informs the perceptual processes in the brain. These processes help us determine and recognize objects, their visual qualities and attributes, and distinguish them from each other. The perceived attributes of objects enables us to understand our surroundings. Even though the visual qualities in our surroundings are shifting constantly, our visual system helps us recognize matters despite variance in appearance. This process is called visual constancy (Cuttle, C. 2003).

Fig 1: In the left image the wall is perceived as white, although the cast light appears orange. Images by Merete Madsen.

The same process enables us to differentiate colors in the visible spectrum. Our color perception is relative and highly subjective, our vision adapts to perceive color and light by our recognition.

Evolutionary, our eyes are designed and adapted to daylight, the white light emitted from the sun which contains a full color spectrum.

Through our visual perception, we are able to perceive colors as they would appear in daylight, regardless of the lightning condition. We still perceive the wall as being white during sunset, although the color cast from the direct light appears orange [Fig 1]. What is also important to consider when discussing colors in a spatial context is that naturally, colors do not appear isolated but in relation to the colors around them (Yot, R. 2020).

2. Background

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2.2 Optical properties of materials

As described above, our visual perception enables recognition of object attributes. However, this process only occurs in the interactions when light encounters matter. The optical properties of a material define how they interact with light. It is dependent on the incident radiation and the type of material, its chemical composition, structure and surface qualities. The interaction processes which are most fundamental are absorption, reflection and transmission [Fig 2]. It is light that enables our perceptual process to determine differences of opaque, transparent and translucent materials (Cuttle, C 2003).

Fig 2: Schematic visualization and examples from visual study of optical properties.

Absorption: Common to almost all materials is that they absorb light. Absorption is the property that enables us to determine surface lightness, and through selective absorption, surface color.

Reflection: Materials reflect light differently depending on their atomic structure. Reflection can be divided either as diffuse or direct. Diffuse reflection is the most encountering type of reflection and is an important property for us to determine volume, depth and dimensions to objects. As absorption, diffuse reflection is a part of the quality that reveals surface color. In direct reflection, the light is reflected in a specular manner. One main quality of specular reflection is to give information about the surrounding environment (Yot, R. 2020).

Transmission: Some materials let light pass through them, this is called light transmittance and is a property of transparent and translucent materials. In transparent materials there is no scattered light, whereas in translucent materials diffusion occurs. Refraction is the effect when light passes from a transparent material into another, causing bended light rays. Almost all transparent materials are partially reflective and partially refracted (Yot, R. 2020).

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Fig 3: Optical properties seldom appear isolated, but rather mutually, but to different levels of degree.

This is described by Clarence Rainwater in his book Light and Color.

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Fig 4: This image shows a selection of material samples in direct daylight, in which the different optical properties of each material are visually obvious. The wood reflects light in a diffusive manner, whereas the direct reflection

occurs on the surface of the brass sheet. The transparent glass lets light pass through, at the same time bending the light rays in which the refracted light is visible.

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2.3 Materials used traditionally for luminaries

Materials used for luminaries have evolved from the use of candles, gas lights and oil lamps to the introduction of electrical lighting in the early 20th century. Over the years, our relation to light has changed and so has the design of luminaries. There are many examples of how we’ve taken advantage of the qualities of different materials, in order to control the light and to change its character.

Metal: Most luminaries include some metal components. The advantage of metal is its strength-to-weight ratio and long lasting shape. Metal could also work as the central element in a lamp, often used as a reflector itself, but also as an ornament. An early example is the chandelier, made of metal and prism used to increase reflection from the candles [Fig 5] (Muro, R. 2020). Wall mounted candle holders were (and are still) often made of the same material, for the same reason.

Fig 5: Schematic figure showing the reflection from a chandelier (by Rodrigo Muro), Taklampa 2126 from Svenskt Tenn and Chiara Table lamp from Flos

Glass: Before synthetic compounds, glass was the main choice for transparent or semi-transparent material of choice for luminaries. Glass has been used for oil lamps, traditionally, as well as for almost any typology of luminaires today. The main quality of glass is its ability to transmit light. Semi-opaque glass can have a glowing effect with indirect light, whereas clear glass causes direct light and when lightened up in a certain way creates decorative lighting effects caused by refraction.

Fig 6: Glass luminaries from left to right: A traditional oil lamp in clear glass, an old industrial lamp with frosted glass frame, Poul Henningsen’s PH lamp in frosted glass, Putki table lamp by Matti Klenell, for Iitala.

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Plastic: In the 50’s, the application of plastic as material for luminaries was introduced at the time and became the new main material, along with metal, glas, and textile. The use of acrylics and plexi became common, due to its transparent and translucent ability to let light through, but also because it’s ability to shape easily, lightweight, tough and cheap. Today, plastic is often used instead of glass due to their common transitive ability (Garnert, Jan. 2016).

Fig 7: Plastic luminaries from left to right: Verner Panton lamp Leila design in 1960, IKEA Fillsta Pendant, HAY PC portable lam and Riff series from Atelje Lyktan.

Wood: Wood is most often found as an opaque material, although sometimes when processed very thin it becomes translucent. Hans-Agne Jakobsson used wood when designing a luminaire for a Christmas display and got attention for its capacity to spread warm, cosy light, mimicking the light from a fireplace (Garnert, Jan. 2016).

Fig 8: Wooden luminaires designed by Hans Agne Jacobsen.

Fabric: Fabric, especially silk, was commonly used for shading in the early 20th century.

Fabric adds light diffusion, and could be found either solid or translucent.

Fig 9: Luminaire screens made of fabric. From left to right: Pendant 2560 designed by Josef Frank, fringe pendant (unknown), Liv lamp designed by Jonas Bohlin and Hood Mini felt from Atelje Lyktan.

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2.4 Material selection taking sustainability into consideration

When comparing materials we could either discuss their lifecycle, if they are renewable, taken from natural resources, how they are manufactured or their ability to be recycled. From the perspective of the product on the other hand, factors include the production process as well as the lifespan of the product, how it is taken care of and its probability to be discarded. In “Materials and Design. The Art and Science of Material Selection in Product Design” (2010) Ashby and Johnson discuss there is no simple answer of what material to select when designing a product when taking environmental aspects into consideration.

“The most obvious ways to conserve material is to make products smaller, make them last longer and recycle them when they finally reach the end of their lives. But the seemingly obvious can sometimes be deceptive. Materials and energy form part of a complex and highly interactive system”

(Ashby, M. Johnson, K. 2010).

Passive products don't require much energy to function. In their case, the production and manufacturing processes are the ones that dominate the consumption of energy and materials. When considering energy-consuming products such as luminaries, the greatest potential for improvement is condering use and disposal rather than manufacture. (Ashby, M. Johnson, K. 2010).

This question is as important for luminaire design, not only when choosing the light source but also when designing the light fitting. Taking material properties such as reflectency as an example, the qualities of the material could benefit in increasing the light level resulting in lower lumen output needed, therefore less energy required.

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3. Methodology

The methodology followed to investigate the objectives of the thesis, to get a better understanding of how optical properties could be used as a tool in the process of designing a luminare was divided in three main steps: Step 1) Literature review where the objective was to get knowledge in the investigation field. Step 2) A small scale visual laboratory, where qualitative and quantitative aspects were observed, measured and evaluated. Step 3) A full scale testing, where quantitative aspects were observed and evaluated.

Fig 10: The main steps of used methods, numbered after the title for each section.

3.1. Limitations

The intended outcome of the thesis is to work as a tool during the process of designing a luminaire, excluding the last part of the process, the realisation, which in a common design process would be a prototype of the luminaire [Fig 11].

Fig 11: The design process steps, showing the steps that are included and excluded in the paper.

3. Methodology

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3.2 Literature review

A literary study was applied, in order to get information on:

i) The human perception in relation to light, color and objects.

ii) Optical properties of different materials.

iii) Materials used for luminaries in the past and today.

iv) Sustainable considerations in product design.

The investigated topics were chosen with the aim to give knowledge of how to select materials in the process of designing a luminaire.

3.3 Small scale visual laboratory - intentions

The take-off for the thesis was a visual laboration, where the intention was to observe how different materials interact with light in a small-scale model of a room. The hypothesis of the laboration was that reflected light from the different materials influences the atmosphere of its surroundings. The purpose of the small scale laboration was to prove the theory in a controlled manner, where additional elements and factors were extracted.

3.3.1 Selection of space

The visual laboration was carried out in a box, where the proportions were selected in relation to the size of material samples used in the test [Fig 12]. The walls and ceiling of the box was covered with white, matte paper, for the sake of reflecting as much reflected light as possible from the object placed in the box. The floor was covered in matte black paper for the sake of absorbing as much direct light as possible, only leaving the reflected light from the material to be seen on the walls and in the ceiling. The lamp was placed with a distance of 10 cm to the material sample, to get as much reflected light from it as possible.

Fig 12: Schematic image of box dimensions and light distribution.

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3.3.2 Selection of light source

The artificial light source used in the test was chosen due its ability to focus the light downwards, towards the object [Fig 13]. The properties of the lamp were chosen since they are commonly used in domestic environments in Scandinavia. The setup of the laboratory was executed in a dark room, without daylight or any other light source other than the one used in the laboratory.

Fig 13: Artificial light source used in the small scale laboratory.

3.3.3 Selection of materials

14 different material samples, commonly found in domestic environments and used for interior design, were observed in the test [Fig 15-16]. Further, the materials had different optical properties.

Since the study was limited by the constraint of resources and time, the material samples were pre-cut and selected after their availability.

Fig 14: Snapshot of some materials used in the small scale study.

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wood

leather

stone

oak

color: medium brown

color: black

color: yellow light brown

color: white

color: grey with black stains

color: light brown

nubuck granite, polished pine leather granite, matte ash

material study - samples

Fig 15: Table of material samples from wood, leather and stone.

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metal

metal + glass

glass

aluminium, brushed mirror, clear glass, clear brass, brushed mirror, colored glass, frosted glass, colored

material study - samples

color: - color: -

color: grey, silvery

color: - color: black

color: yellow, golden

color: yellow

Fig 16: Table of material samples from metal and glass.

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3.3.4 Qualitative measurements 3.3.4.1 Light levels, CCT and CRI

Illuminance, CCT and CRI were measured with a spectrometer. The objective of looking at only those metrics and not others, was that those easily could be compared with qualitative ones. Intentionally, both measuring points were placed in indirect light, to measure reflected light from the material and to avoid direct light from the lamp.

Fig 17-19: Measuring points and photo from laboratory using the spectrometer.

Fig 18-19: Photos from laboratory using the spectrometer in both measuring points.

Fig 17: Schematic image of measurings points.

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3.3.5 Qualitative measurements 3.3.5.1 V/P analysis

As a tool for analysing the light qualities of each material in the model, Anders Liljefors’s V/P lighting theory [Appendix A.1] was applied in a qualitative manner and executed personally (Liljefors A., Ejhed J.).

Fig 20: V/P analysis template. Looking at one certain quality at the time made it easier to distinguish the optical properties of each material. In order to break down the analysis, the space was divided into four light zones,

named A-D.

Fig 20: V/P analysis template. Looking at one certain quality at the time made it easier to distinguish the optical properties of each material. In order to break down the analysis, the space was divided into

four light zones, named A-D.

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3.3.5.2 Lightness meter

A NCS lightness meter was used as a tool to define the lightness value of the surface color of the reflected light on light zone C in the visual laboratory. The lightness was evaluated by comparing colour samples from the greyscale against the surface on the wall to define colours’ lightness value.

Fig 21: Photos from lightness meter measurement session. The greyscale sample that showed the most distinct similarity with the surfaces’ colour was defined to have

roughly the same lightness value.

3.3.5.3 Own impressions and observation

Personal observations were written down in a subjective manner during the laboratory, in order to be able to document and overlook the impressions of each scenario.

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3.3.5.4 Survey

For the sake of diverse input and as a tool to get a compilation and measure of subjective impressions, the survey worksheet Assignment Module 3 (Am03-KTH/AAU) from L4H summer school #2

(October 2020) [Appendix A.2] was applied and answered by 27 persons. Out of 14 tested materials in the visual laboration, six of them were shown in the survey, selected since they all appeared similar to environments that could be found in a domestic environment.

Fig 22: Survey template, showing one out of six images used in it. The subjects were asked to choose 5 words that they associated images of different lighting scenarios with, as well as mark one word that best described the time of the day that they perceive the image to be in. The 21 words used in the survey

were selected due to the subjectiveness of their meaning.

Fig 23: All 6 lighting scenarios shown in the test. The light source and the samples were erased in the images, to minimize the risk that the subjects could have association to those objects

and thereby affect the answers of the survey.

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3.4 Full scale testing - intentions

The intention of the full scale testing was to observe how different materials interact with light, and how they modify the space visually, in a full scale situation. Material samples in different shapes were created, combined with a light source and experimented with in a spontaneous manner. The purpose of the full scale testing was to build a set of mock-ups, as a part of the process for designing a luminaire and with the expectation that the different compositions could be used as the foundation for the design.

3.4.1 Set up of full scale testing

The room used in the test was selected for the reason that the proportions of it and it’s interior colors and materials are considered as, to some extent, common in Scandinavian homes. The intention of keeping the room unfurnished, except for one white table, was to be able to ease the evaluation of how materials affect the space.

Fig 24: Plan and section of the room used for full scale testing. The full scale testing was carried out in an unfurnished room located in Södermalm, Stockholm. The walls and ceiling of the room were painted white and the floor was made of pine wood. In light source position 1, the lamp was placed centered on the table, for the

reason to get as much reflected light from the material as possible. In position 2, it was attached to the wall.

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3.4.2 Selection of light sources

The full scale test included daylight with the aim to observe how natural light in combination with artificial light interplays with the materials. The testing was executed during several days and at different times of the day, in indirect daylight and during dark hours. Besides, all testing was done with one single artificial light source [Fig 25]. The reason for testing only one light source was to be able to analyse how the light was modified, purley on attached material. The reason for choosing the light source was due to its flexibility to be controlled and integrated into a mock-up. The properties of the lamp were chosen since they are commonly used in domestic environments in Scandinavia.

Fig 25: The used light source was an LED module with a coned reflector attached (and paper or thin wood wrapped around it to cover the heat sink).

3.4.3 Mock-ups

110 mock-ups in different materials and shapes were created to be able to compare their visual variety and influence on the room used in the test. The criteria for evaluating the mock-ups was their ability to distribute light and visually change the perceived character of the surrounding space.

3.4.4 Own impressions and observation

Personal observations were written down in a subjective manner during the visual laboratory, in order to be able to document and overlook the impressions of each scenario.

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Fig 26-27: Snapshots of materials used for mock-ups in the full scale test

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4. Results

4.1 Small scale visual laboratory

Results from the small scale visual laboratory showed quantitative measurements using the spectrometer, as well as qualitative measurements using the lightness meter, v/p analysis, own observation and the survey.

4.1.1 Spectrometer

In figures 29-32 follows the measured values of illumination, color temperature and color rendering in the small scale laboratory, for each material sample. During the test, in some cases the light level was too low for the spectrometer to measure. This is why some of the scenarios are missing information.

When evaluating the space without any material sample, the spectrometer was unable to detect any measurement. Therefore, there was no validation of how the color temperature coming solely from the light source affected the space.

Fig 28: Notes explaining comparison of measured results in the small scale laboratory.

4. Results

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Fig 29

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Fig 32

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4.1.2 Lightnessmeter

The lightness meter test showed lightness levels between 0,90-0,95 in all scenarios with material samples [Fig 33]. The lightness level in the box without any material was measured as 0,90.

Fig x: Results from NCS lightness meter test.

Fig 33

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4.1.3 V/P analysis

The V/P analysis showed a variance of results in zones A, B and C. The result showed the greatest difference in perceived level of light, reflection and color of light, whereas the results of perceived level of spatial distribution, glare and color of surfaces were more uniform. However, in zone D the results turned out similar, often showing high levels of perceived glare and a clear hotspot.

Fig 34: Example of analysis result, frosted glass.

4.1.4 Own impressions and observation

In figure 35 below follows notes taken from the small scale visual lab, explaining perceived qualities of each material category.

Fig 35

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4.1.5 Survey

The results of the survey showed that both scenarios 1 and 3, including wood samples, were marked as ‘warm’, ‘cosy’ and ‘relaxed’. The three scenarios that were marked as ‘warm’ were also marked as perceived as being ‘afternoon’ or ‘evening’ [Fig 53, 59, 62 in Appendix]. Scenario 2, 5 and 6 were marked as ‘cold’, however they didn't seem to have any direct correlation to time since they were perceived differently, as both ‘morning’, ‘noon’ and ‘night’ [Fig 56, 65, 68 in Appendix].

Generally, the results showed that the scenarios with lower light levels were perceived as more

‘intimate’ and ‘private’, compared to the brighter ones which were more often marked as ‘public’ and

‘formal’ [Appendix A.3].

Fig 36: Example of survey results, scenario 3 and 5. See Appendix A.3 for all results.

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4.2.1 Full scale testing mock-ups

The total number of mock-up scenarios was counted to 187, however a number of them were extracted due to lack of quality, leaving 145 scenarios selected as valid mock-ups for the test. The result of the full scale study showed a large span of variation in how the different materials affected the room, shown in Fig 38-45. See Fig 71-78 in Appendix for material specification of each mock-up.

Fig 37: Examples of 4 different mock-ups.

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Fig 38

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Fig 39

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Fig 40

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Fig 41

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Fig 42

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Fig 43

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Fig 44

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Fig 45

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4.2.2 Own impressions and observations

In figure 46-48 below follows notes taken from the full scale visual lab, explaining perceived qualities of each material category, as well as general comments.

Fig 46Fig 47Fig 48

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5. Discussion

The discussion part of this paper could aim specifically to look into the results of the study, comparing the differences between the optical properties of the studied materials. Instead, the focus of this discussion is to evaluate the methods used in the investigation and in what way they contribute in the process of designing a luminaire, as well as encouraging the reader to explore the possibilities of each material themselves, by experimentation and observation.

5.1 Using an experiment-based approach in the process for designing a luminaire

One main quality of the design methodology is its unpredictability, going back and forth between phases in the process. Looking at each method used in this investigation, one could conclude that all of them, either literature-based or experiment-based, fulfilled different purposes of answering the main question. At the same time, the steps in the process became somehow dynamic, allowing the motivation, research and synthesis phases to influence each other and change during the process.

Literature review: As in any other field, one part of the investigation process includes a literal research phase. In the design process in particular, this phase often plays an important role for setting the context of the project, such as gaining information about the user or other aspects such as environmental or economical. In this investigation, the research of the physics behind optical properties helped in order to understand why the materials influenced the light as it did during the visual laborations. The read up on human visual perception contributed when analysing the results of the laborations, as well as understanding how different contexts might influence the perception of a luminaire.

Small scale study: Although it is valuable for a lighting designer to understand the physics of different materials, one could argue that the most essential way of learning is by observation, documentation, experiments and discussion. The application of the small scale study was a simple way of comparing the different material’s ability to reflect, transmit or absorb light by looking at how much light was reflected in the box. It should be noted that if changing any parameter of the laboration, such as the used light source, the dimensions, surfaces of the box, material samples sizes, the qualities of the reflected light would have appeared differently. However, the purpose of the test was not to measure any exact values, rather to explore the possibilities of letting different materials influence the indirect light, and further, how the lighting effect influenced the perceived atmosphere of the space. Using the spectrometer and the lightness meter was a useful way of determining how the material affected the room in terms of light levels and color, whereas the V/P analysis and the personal observations contributed to evaluate perceived factors such as distribution, shadows, reflections and glare. The advantages of using a survey to analyse what atmosphere the reflected light from each material caused, was mainly to be able to compare and connect how different qualities of light are associated with certain impressions.

Full scale study: Moving from small scale into full scale came as a natural step in the process.

One of the main qualities of the full scale study was that it showed its great potential in altering a large span, over 100 variations, of mock-ups from only one single light source. A fruitful part of the full scale study was when combining materials. One could say that the different material samples were used as tools in a toolbox for either emphasizing, muting, directing or adding color. For example, when assembling thin glass and thick wood; the glass worked as part of the luminaire that distributed the light and the wood functioned to shield for glare, to lower the light level and to add warmth.

5. Discussion

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For further development, the design of a luminaire does not necessarily need to correlate identically to the laborations, rather to be used as a reference of how different materials interplay with light and what that does to the perception of a space. The laborations were controlled tests, arranged with white walls and no objects within the space. In a real domestic scene, there are supplementary interior colors, objects, materials and surface textures.

The full scale study demonstrated that a very small amount of material could affect a large amount of the room, most apparent in color temperature, color tone and light levels but also in reflection and shadows. Although, this might not always be the case since the amount of reflected light is very much dependent on the properties of the light source, the distance and direction from the material to the light source, and the surrounding space. A valuable insight from the full scale testing however, was the interplay between the mock-ups and daylight, which contributed to a more accurate domestic scene.

However, the intention of the investigation was not trying to imitate a real scenario, but rather to understand how materials affect an environment where additional elements and factors are extracted.

A lighting designer with knowledge of the optical properties of different materials has an advantage to be able to analyse and understand in which way the materials will affect the space during different lighting conditions. One could conclude that the gained knowledge from the investigation are useful when designing a luminaire and emphasize that not only the light source and shape of the luminare affects what light will come out of a luminaire, but also the material in terms of how it reflects, absorbs and transmits light. In addition, one could argue that a sustainable approach towards material and production is to appreciate the visual differences of each material and to be able to make use of them based purely on their optical qualities.

5.2 The human perception

When looking at the images from the laborations, it is obvious how the materials affected the visual character of the surrounding space. At the same time, comments from the survey and personal observation, proved that the factor of visual constancy was apparent. Even though the character of the lighting changed distinctly, the box and the room were still perceived as spaces with white walls.

What really changed in the perception of the viewer was the described mood and feeling of time.

Results, both from the survey and personal observation, proved that the perception of the atmosphere of the analysed spaces varied depending on what light character each material reflected.

Looking specifically at the result from the survey, one could conclude that the perception of color temperature and light levels were the factors that to the largest degree affected the atmosphere. This conclusion could be drawn by looking at the correlation between the answers from the survey and the visual similarities of the named factors, when comparing the six different scenarios [Appendix A.3].

What should be taken into consideration when analysing the results from the survey is that there is a large distinction between looking at images of light settings and experiencing them in real life. An obvious concern is an image's lack of ability to capture the whole room, leaving what can't be detected in the image for the viewer's imagination. This issue was also experienced in the full scale study.

Looking at the images, it is not clear in which settings there was a lack of visual ergonomy and a high level of glare.

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5.3 Suggested design/concept of a luminaire

With an educational background in industrial design, already having the knowledge and experience of how to develop a prototype for a luminaire, the focus of this thesis was rather to focus in depth on the tools for selecting material in the process of designing a luminaire. Overlooking the next steps when designing a luminaire could be helpful in order to identify the method of applying the gained knowledge of the investigation of this paper. Even though the design process was presented as a chronological account in the method part of this paper, the more accurate way it was executed was in a dynamic way going back and forth between the phases of the project [Fig 49].

Fig 49: A suggestion of the next steps in the design process.

Since the intended context of the investigation is a domestic environment in Scandinavia, the material selection for the luminare would reflect this. As for the focus of the study in general, the main target of the function of the luminare would be ambient lighting, with the function to provide indirect light reflected from the material.

Inspired by mock-ups number 66-69 [Fig 41], the suggested shape of the luminare would be a quite simple design, leaving the materials as the center of attention rather than the object itself. The focused typology of the luminare would be a multi-functioning design, that could be applied both as a table lamp, on the wall or in the ceiling.

The design proposal would suggest a product family of luminaires, where a small removable part of the luminaire which is emitting indirect light, could be produced in different materials. Highlighting what was addressed in the background section considering energy-consuming products; that the most crucial part of sustainable improvement lies in examining use and disposal, and in accordance with the UN Sustainability Goal 12, one can conclude that a valid choice would be to design the luminaire in a way that eases the recycling process and assembled so that they are easy to separate. Having a small removable part would give the possibility to adjust the character of the light from the luminaire depending on the interior settings or reuse it when changing the spatial settings over time. In addition, in accordance with the UN Sustainability Goal 9, local materials taken from natural resources would be considered first, as well as collaboration with small-scale industries(United Nations, 2015).One could also suggest that a maintenance statement for the luminaire should be formulated, in order to increase the lifespan of the materials of the product. The development of technology for achieving the best possible lighting solutions to promote health would also be supported, taking visual ergonomics such as glare, flicker, and light levels, to name a few, into consideration.

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Fig 50: Suggested design/concept for a family of luminaires

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6. Conclusion

Looking at the visual laborations executed in this paper, one could conclude that there is a wide variance in how materials with different optical properties interact with light. Light can either emphasize or mute the qualities of different materials, at the same time materials manipulate the character of the light and its distribution. The understanding of how to make use of the differences between those materials is a valuable part in the process of designing a luminaire. Further, looking at it from a visual point of view, there’s an advantage of being aware of how very small details and changes in the environment have an ability to change the character of its surrounding, purely based on the characteristics of the material itself.

Irrespective of under what circumstances we are designing for, light and material are inseparable and in constant relation to each other and to changes in the surrounding. Furthermore, the experience of light is perceptual, we perceive the surrounding world with our senses and connect them to our emotions. During the process of this investigation it was relevant having the complexity of comparing light scenarios and drawing absolute conclusions from them. For example, the lighting effects from a luminare might be perceived very differently depending on which context it is put in. Although light is inconsistent and relative, it doesn't mean that incidents from isolated testings can't be valid or used as reference for other situations.

Considering the process of designing a luminaire specifically, but also in planning lighting in general, one could conclude that even the smallest discoveries might be valuable, to some extent even crucial.

With that said, I would like to promote the potential in devoting time to analyse and discuss what we see. Through the investigation of this paper, one could argue that a useful method for gaining those lighting experiences are by hands-on experiments and observation. Further, those experiences could work as a reference tool in the process of designing a luminaire as well as when planning a light and are valid not only for product designers, but for lighting designers, interior designers or architects.

From a personal point of view, the investigation of this paper proves a great potential in the learning-by-doing approach, in which I would like to encourage experimentation, testing and using mock-ups.

6. Conclusion

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7. References

Bibliography:

Ashby, Mike. and Johnson, Kara. “Materials and Design. The Art and Science of Material Selection in Product Design”, Second Edition, 2010, Butterworth-Heinemann

Attained (23-05-2021) at:

https://www-sciencedirect-com.focus.lib.kth.se/book/9781856174978/materials-and-design Page 67-71

Cuttle, Christopher. “Lighting by Design”, 2003, Architectural Press Page 3-31

Fukasawa, Naoto. “Pao collection by Naoto Fukasawa - Glass pendant and glass table lamp now available”

https://hay.dk/sv/news/news-2020/pao-collection-by-naoto-fukasawa Garnert, Jan. “Ut ur mörkret”, 2016, Historiska Media

Page 120, 147-148, 183

Millet, Marietta. “Light Revealing Architecture”, D/A Magazine issue #3 Attained (14-03-2021) at:

http://thedaylightsite.com/light-and-materials/

Rainwater, Clarence. “Light and Color”, 1971, Golden Press, NY, Western Publishing Company Page 40

Yot, Richard. “Light for Visual Artists”, Second Edition, 2020, Laurence King Publishing Ltd Page 65-66, 73, 81, 91-94, 102

United Nations. “The 17 Goals by United Nations”

https://sdgs.un.org/goals 7. References

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Images:

[Fig 1]:

https://canvas.kth.se/courses/21515/files/folder/03-%20Lectures/Merete%20Madsen?preview=378681 2

[Fig 3]:

Rainwater, Clarence. “Light and Color”, 1971, Golden Press, NY, Western Publishing Company Page 40

[Fig 5]:

https://canvas.kth.se/courses/20817/files/folder/03-%20Lectures?preview=3226572 https://www.svenskttenn.se/sv/sortiment/belysning/taklampor/taklampa-2162/100021/

https://flos.com/products/table/chiara/chiara-t/

[Fig 6]:

https://cottagelife.com/design-diy/how-to-refurbish-and-use-old-oil-lamps/

https://www.nigeltyas.co.uk/media/catalog/product/h/o/holmfirth-pendant-light-with-large-opalescent- white-coolie-shade-1-thumb.jpg

https://orebrohem.se/har-ar-lampan-putki-av-matti-klenell-en-framtida-klassiker/

https://www.louispoulsen.com/en/catalog/private/table/ph-3-2-glass-table?v=91688-5744166179-01&

t=about [Fig 7]:

https://www.artfurniture.co.uk/item/sold/verner-panton-1960s-table-lamp-leila- http://www.ik-press.com/sk/detail-fotografie/fillsta-zavesna-lampa-3/

https://www.crocus.co.uk/product/_/pc-portable-light-olive-green/classid.2000041226/

https://www.ateljelyktan.se/en/products/riff-mini-pendant?color=whiteRal_9016 [Fig 8]:

https://www.twoenlighten.com/vintage-floor-lights/1960s-hans-agne-jakobsson-wood-tripod-floor-la mp-for-ab-ellysett-floor

https://www.incollect.com/listings/furniture/lighting/hans-agne-jakobsson-pair-of-1960s-hans-agne-ja kobsson-wood-table-lamps-for-ab-ellysett-260906

https://www.ztijl.com/mid-century-design/lamps/pendants/swedish-pendant-by-hans-agne-jakobsson-f or-ellysett-1960s/

https://virtualgeometry.tumblr.com/post/644913093990825984/1960s-hans-agne-jakobsson-model-24 3-wood-table

[Fig 9]:

https://auctionet.com/sv/844596-taklampa-modell-2560-josef-frank-firma-svenskt-tenn https://www.heals.com/fringe-pendant-natural.html

https://www.bukowskis.com/sv/lots/1256170-jonas-bohlin-golvlampa-liv-klong https://www.ateljelyktan.se/en/products/hood-mini-pendant?color=blueGreen All other sources are taken or produced by the author.

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8. Appendix

A.1 The Visual/Perceptual Theory:

This tool, developed by Jan Ejhed, is a subjective visual estimate of lighting qualities; Level of Light, Spatial distribution of Light, Reflections, Shadows, Glare, Colour tones of Light and Colour (of objects and surfaces). Source: Ejhed, Jan., 2020, QUALITY OF LIGHT: V/P – Lighting Theory.

[PDF].

https://canvas.kth.se/courses/20819/files/folder/02-%20Lectures/pdf/20201113_Jan%20Ejhed%20V_

P%20Theory%20Diana%20Joels?preview=3543541 (Fetched 13-11-2020).

A.2 Assignment Module 3 (Am03-KTH/AAU) from L4H summer school #2, October 2020.

(Original source:https://journals.sagepub.com/doi/10.1177/1420326X21991198)

Fig 51

8. Appendix

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A.3 Survey “Moods”. Applied between 19-04-21 to 30-04-21 Link to survey:

https://docs.google.com/forms/d/e/1FAIpQLSdHWajTPDqKqBqeq6RNWdgIdZH73Icad51Do8O8KT hxSD-5Dg/viewform

Fig 52

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Fig 53

Fig 54

Fig 55

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Fig 56

Fig 57

Fig 58

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Fig 59

Fig 60

Fig 61

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Fig 62

Fig 63

Fig 64

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Fig 65

Fig 66

Fig 67

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Fig 68

Fig 69

Fig 70

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A.4

Fig 71

luminaire mock-up testing 1: 070521, night, table lamp

1 none

2

glass lens, frosted horisontal

3

glass lens, striped horisontal side A

4

glass lens, striped horisontal side B

5 glass container

6 glass container duble

7 glass sculpture small

8 glass sculpture medium

9 glass sculpture ball

10

glass plate, frosted

11

glass plate, clear

16 wood, dark colored thin, curved

17

mirror, paper curved position 1

18

19

20

paper, black curved 12

PVC, frosted rolled horisonalt

13 PVC, frosted rolled vertical

14 PVC, clear rolled horisontal

15 wood, light colored thin, curved

1-20

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Fig 72

luminaire mock-up testing 1: 070521, night, table lamp

21-40

21 glass lens, frosted +

ceramic plate, brown

26 glass lens, frosted + aluminium sculpture

31 glass container + oak, thick

36

white paper, thin shape 1

ceramic plate, red

27 glass lens, frosted + glass lens, striped + wood, dark colored, thin

37

23 glass lens, frosted + wood, dark colored, thin

28 glass lens, frosted vertical

white paper

38

24 glass lens, frosted + glass scultpure + wood, dark colored

29 brass flat

34 blass ball +

glass lens, frosted

39

PVC flat, clear +

glass lens, frosted

25 glass lens, frosted + glass scultpure, small

30 aluminium flat

35

leather sleeve, brown

40 wood, dark colored, thin

+

glass lens, frosted

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Fig 73

luminaire mock-up testing 1: 070521, daylight, table lamp

41-60

41 none

42

glass lens, frosted

43 glass lens, striped horisontal side A

44 glass container duble

45 glass container position 1

46 PVC, frosted rolled

47 PVC, frosted rolled vertical position 1

48 PVC, clear curved

49 PVC, clear rolled horisontal

50 PVC, clear rolled vertical position 2

51

glass plate, clear

56 glass sculpture medium

57 glass sculpture small side A

58 glass sculpture small side B

59 glass sculpture ball side A

60 glass sculpture ball side B 52

glass plate, frosted

53 glass container position 2

54 glass container + pine, thick

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Fig 74

luminaire mock-up testing 1: 070521, daylight, table lamp

61-70

61 wood, light colored thin, flat horisontal

66 glass container +

granite, grey

62 wood, light colored thin, flat angled

granite, brown

63 aluminium sculpture

leather, black

64 glass container + ash, thick

mirror, frosted

mirror paper, flat

70

mirror, black

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Fig 75

luminaire mock-up testing 2: 120521, night, wall lamp

71-90

71

mirror, paper small flat

76

wood, dark colored thin distance 3

72

wood, pine, thick small

82 wood, ash, thick small

87 well paper circle large

83

mirror, paper medium flat

88

mirror, paper large curved

89

white paper, thin

large flat

90

black paper, large flat 84

glass lens, frosted veritcal

85 glass lens, striped veritcal 81

wood, oak, thick small

86 glass container clear small

77

wood, light colored, thin small

73

mirror, paper small curved

78 wood, medium brown small

74

79 aluminium medium flat

75

80 brass medium flat

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Fig 76

luminaire mock-up testing 3: 140521, night, large table lamp

91-110

91 PVC, clear rolled vertical

101 PVC, clear rolled vertical +

mirror, paper position 1 curved

mirror, paper distance 1 flat

mirror, paper distance 2 flat

mirror, paper position 8 curved 96

PVC, clear rolled vertical +

white paper, thin shape 6 large

white paper, thin shape 2 small

white paper, thin hape 3 large

white paper, thin shape 5 medium

white paper, thin shape 10 medium

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Fig 77

luminaire mock-up testing 3: 140521, night, large table lamp

111-130

aluminium flat

brass flat

aluminium cone

wood, dark colored thin flat

wood, dark colored thin curved

wood, med.

colored thin curved vetical

wood, med.

colored thin curved angled 1

wood, med.

wood, light colored thin curved veritcal

wood, dark colored thin curved veritcal

wood, dark colored thin flat horisontal

wood, large flat vertical 1

wood, large flat vertical 2 122

wood, large flat horisontal distance 1

oak, thick

glass container

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Fig 78

luminaire mock-up testing 3: 140521, night, large table lamp

131-145

glass lens, frosted side A position 1

ceramic, grey, small

ceramic, grey, medium

wood, thick medium brown, medium

aluminium curved 132

glass lens, frosted side A position 2

ceramic, white, small

glass lens, frosted side B

paper, black horisontal curved

ceramic, brown, small

paper, black vertical curved

ceramic, red, small

well paper horisontal flat

well paper vertical flat

leather sleeve, brown

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