FINAL CONCLUSIONS

The result of the investigation about the three research questions are here finally concluded.

The questions in the theoretical framework are associated thematically to the appropriate research question.

5.5.1 Research question nr. 1

TF Part 1. Research question number 1. Why and in what way should daylight and artificial light be designed for the indoor environment to realise goals of visual comfort and light-related health:

Light is fundamental to life and needs to be carefully designed [Hanifin & Brainard 2007; Wirz-Justice & Fournier 2010] since connected in a solid way to basic human health.

“Light profoundly impacts human consciousness through the stimulation of the visual system and powerfully regulates the human circadian system, which in turn, has a regulatory impact on virtually all tissues in the body” [Brainard & Hanifin 2005].

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Daylight should be used as ambient light [Hollwich 1979] in the indoor environment and be completed with a daylight mimicking artificial light [Hollwich 1979; Hannibal et al. 2007] that supports humans PPV. The use of the UCLDP will increase the possibilities to fulfil goals set out for visual comfort in EN12464-1:2011 and light-related health in EC Treaty 137 and WHO Target 9 and 13-17.

TF Part 2. Can significant differences in the interaction of man, light, colour and space in the outdoor and indoor environment be identified: Significant differences between the interaction of MLCS seen in the outdoor and the indoor environment are the wavelengths and the rhythm of daylight [Hollwich 1979; Brainard & Hanifin 2005].

TF Part 3. Which are the functions of melanopsin and ipRGC and how can a relation to lighting design and light-related basic health be formulated: The chemical structure of melanopsin in ipRGC opens up for some wavelengths to reach the melanopsin and contribute to action potentials to the brain. Artificial light sources need to be developed to emit (safe) wavelengths that have the possibility to enter the eye and give action potentials close to the one seen in the outdoor environment. Melanopsin and ipRGC receive signals from daylight for onset and offset of the diurnal rhythm. Artificial light need to be designed in a way that do not risk interfere with the signals for onset and offset of the diurnal rhythm seen in daylight and to be adapted to the light at the site where the user lives [Brainard & Hanifin 2005].

TF Part 4. Can patterns be seen in responses to PS and in preferences to light when subjects stay in daylight or artificial light in the room and light settings in the studies:

Study 1: Only preferences were collected.

Study 2: Minor differences can be seen in mean for measured hormonal levels in the

bloodstream when staying in the three room and light settings. Mean for cortisol follows the same pattern in changes in daylight and in artificial light. Changes in mean for adrenaline and noradrenaline differ slightly compared to the pattern of changes seen in daylight. More research is needed to find out if this is a systematic difference that can be related to the

wavelengths emitted from artificial light.

Study 2: Subjects being alert on the highest level is only seen at 25 of 180 occasions of self- evaluation. The highest number of subjects evaluated as alert on level four and seen as natural, was seen in daylight. The highest number of alertness on level 4 evaluated as unnatural was seen in Room 3 at 16.00. The result of the study does not show if this is a systematic difference that can be related to the wavelengths emitted from daylight or artificial light.

Study 3: Only preferences were collected.

Study 4: Only preferences were gathered.

Study 5: Only preferences were collected.

142 Preferences

Study 1: When the lighting designers preferences for visual comfort (close to, far from and very far from) seen in the room and light settings in the study, was compared to the measured preferences for visual comfort (VCT) for the subjects, the result shows that the most visual comfortable room according to the lighting designers preferences was preferred at the most by the subjects. The lighting designer’s preference for a low level of ambient light shown in Room 2 made it possible for the highest number of measured subjects to have their own preferred level of light at the work table but not in the ambient light, compared to in the two other rooms. All subjects in the study preferred a higher level of light at the table compared to the level of ambient light. When associated to the ordinary lighting application it can be concluded that the study shows that it was an advantage to use a low level of ambient light.

When daylight is used as ambient light (to a certain lowest level of security) it gives the user an opportunity to have the individually preferred level of light at the working table. Low level of daylight is here suggested appreciated as visually comfortable.

Study 2: Only responses were collected.

Study 3: When the 87 subjects from 23 countries in study 3 evaluated the light emitted from Halogen, CFL and LED and compared to the light from only LED it was found that Halogen, CFL and LED was found more similar to the light the subjects were used to at home. The light from Halogen, CFL and LED was preferred compared to the light emitted from only LED.

Study 4: The study exhibited a span among the 318 subjects that participated in the study from 80-3940 Lux for the preference for a visually comfortable level of light at the table and 30-1750 for the ambient light in the group of subjects. The subjects varied 50 times in preferences for level of light between each other’s and almost 60 times in preferences for level of a complementary ambient light. The subjects did almost unique combinations of level of light at the worktable and for the ambient light. Only two pairs of subjects had the same preferences, 314 subjects did unique combinations of levels of light.

Study 5: The two subjects in the study varied widely in preferences for level of light at the work table and for the ambient light during 9.00-17.00. The subjects varied from the lowest value 1030 to the highest value 3420 Lux for the level of light at the work table and from 140 to 1010 Lux in the ambient light (TF 2.4).

5.5.2 Research question 2.

TF Part 5. Research question 2. In what way can laws, recommendations and methods for lighting design be developed to support the individual user in a better way PPV: Light is of high importance for human basic health? Laws, recommendations, and methods for lighting design need to be developed to give a user specific support PPV. Laws should not be detailed but the ambition with the law need to be explained related to lighting design. Recommendations need to be focused on flexibility of the lighting application that has the possibility to give the individual subjects a good visual support. Methods for lighting design need to be verified having a positive impact on the public health by health authorities.

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The lighting design process can be described from the perspective of ; 1) the interaction of MLCS; 2) the LDP (in general) step 1-4; 3) and the UCLDP 1-4, that is user specific.

TF Part 5. Will light-related goals according to visual comfort and health stipulated in EC Treaty 137, Pörn´s health theory in WHO target 9 and 13-17 adopted by the Member States of European Region and visual comfort in the European standard for indoor workplaces be fulfilled by the use of EN 12464-1: 2011: No it is not possible to fulfill goals about visual comfort by the use of the recommendation in the standard. Visual comfort is a matter of adaption to the individual user’s visual needs and to the colours and surfaces in the room and this is not done here. It is in the same way not possible to support human’s needs for the wavelengths and rhythm of daylight by the use of a predesigned static level of light and an artificial light source.

TF Part 6. Will the use of the CCLDP and the UCLDP fulfill goals about visual comfort and light-related health in EN 12464-1:2011, EC Treaty 137 and WHO target 9 and 13-17 adopted by the member States of European Region: Goals for visual comfort and light related health by the use of CCLDP or UCLDP. CCLDP done without contact with the user, the colours, surfaces in the space or daylight do not meet the goals of visual comfort in EN 12464-1:2011 or light-related goals of health in EC Treaty 137 or WHO Target 9, 13-17. The UCLDP on the contrary performed in contact with the user and the colours and surfaces in the room and related to daylight at the site were the user lives have the possibility to give an individual experience of visual comfort and light-related health.

TF Part 7. In what way does the end user, designer, or client perspective to LQ differ in PPV support for the user: The experience of lighting quality goes through the user’s senses. The designer or the client does not know the needs for light of the individual user. Lighting quality is a PPV support from light designed close to the individual users needs.

TF Part 7. Three perspectives on lighting quality

The two principal approaches to LQ that can be seen, according to Boyce [Boyce 2003], (evaluated as fulfilling the client´s and the designer´s expectations) are here suggested as being general and not in contact with the individual user´s light-related needs. This can be compared to a third approach to LQ seen in literature and here associated to the lighting design process by the author of the Thesis. LQ is seen as perceived when the individual subject´s needs and

preferences for light PPV is fulfilled and daylight and the artificial light is designed related to the colours and surfaces in the room and connected to daylight in the outdoor environment.

Examples of differences between these three aspects on lighting quality according to a PPV support of the user are:

The designer’s perspective on LQ is general and the designer has no possibilities to feel if the individual user is experiencing homeostatic balance or visual comfort. The designer does not have information about the group of users individually changed needs during the day.

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The client perspective if not the individual end-user is as general as the designers and the client does not have information about when the user experiences homeostatic balance or visual comfort.

The end-user is specific and knows when the chosen light enhances homeostasis and visual comfort or not. The end-user is guided in the use of light by the experience of relief and comfort PPV in the striving towards equilibrium. The reason for the experience of comfort and relief is shown by research of photo biologists, sleep researchers, physiological optics and researchers in lighting and user centred design [Brainard & Hanifin 2005; Roenneberg et al. 2007; Ronchi 2009; Säter 2011; Redström 2006; Davydow et al. 2007].

TF Part 8. How can the process of lighting design be described that support the user´s

individual light-related PPV needs and is related to the colours and surfaces in a specific space and sets the user in contact with the daylight at the site where the user lives?

Interaction of MLCS

Man: Design the daylight in the room close to the users needs PPV. Design a

complementary artificial light that is related to the colours and surfaces in the room and follows daylight to a lowest level of security. Use non glary task lightings and a light source

that mimics daylight.

Light: Analyse daylight and the artificial light in the room.

Colour: Analyse the colours and surfaces in the room.

Space: Analyse the space.

LDP 1-4.