HUMAN-CENTRIC SUSTAINABLE RETAIL LIGHTING DESIGN APPROACH: AN EXPERIMENTAL STUDY

Transcription

1 HUMAN-CENTRIC SUSTAINABLE RETAIL LIGHTING DESIGN APPROACH: AN EXPERIMENTAL STUDY Final report for Jean Heap Research Bursary 2015 Society of Light and Lighting Dr. Feride Şener Yılmaz, Istanbul Technical University Faculty of Architecture Research Assistant

2 Human-Centric Sustainable Retail Lighting Design Approach: An Experimental Study Table of Contents: 1 INTRODUCTION Recommendations for Retail Lighting Design Criteria Visual Comfort Criteria in Retail Lighting Design Energy Efficiency Criteria in Retail Lighting Design Sustainability and Cost Efficiency in Retail Lighting Design STEPS OF THE HUMAN-CENTRIC SUSTAINABLE RETAIL LIGHTING DESIGN APPROACH Step 1. Literature research Step 2. Preparation of human- centric sustainable retail lighting design criteria matrices Step 3. Development of lighting design alternative sets Step 4. Performance Determination of Lighting Design Alternatives Step 5. Experimental tests: Survey-based data collection and analysis Pre-screening results Survey-based data collection and analysis for retail lighting design alternatives Discussion of results CONCLUSION REFERENCES

3 1 INTRODUCTION Retail environments are of the building typologies where the relationship between human factors and lighting conditions are linked closely. Lighting design has direct relations on space perception, visual stimulus, spatial cognition and user behaviour. Quantitative and qualitative perspectives in retail lighting design helps to attract the customers, plays a role on the time spent in the retail environments, experience the built environment and displayed merchandise and customers decision to buy. A proper retail lighting design concept also helps to create a suitable corporate identity and communication. Sustainability is increasingly important in retail lighting design due to the dwindling energy resources, rising energy costs and the negative impact of energy consumption on nature. Retail sector consumes a significant amount of lighting energy due to long opening hours so lighting design phase should also represent a major route to reducing lighting energy consumption and CO 2 emissions. Achieving sustainable retail lighting design is possible with providing the required visual comfort conditions, ensuring users' psychological and physiological satisfaction, energy efficiency, sustainability and optimum cost considerations. Use of advanced lighting control technologies and daylighting in retail environments gives to a building a unique characteristics providing a dynamic ambiance that has positive effects for the mood of staff and customers. In consideration of the above given information on retail lighting, this study aims to explore different parameters affecting human centric sustainable retail lighting design on an experimental basis and obtain a holistic retail lighting design approach. In this chapter, the general principles of human centric lighting are introduced, retail lighting design principles and recommendations are given and the sustainability, energy efficiency and cost affectivity in retail lighting design are discussed. 1.1 Recommendations for Retail Lighting Design Criteria This part of the report, recommendations for retail lighting design criteria are presented. In this regard, the quantitative and qualitative aspects of retail lighting principles and recommendations addressed in International Commission on Illumination (CIE), Illuminating Energy Society (IES), Society of Light and Lighting (SLL) of Chartered Institution of Building Services Engineers (CIBSE) publications as well as standard and other relevant resources are investigated. The European Standard EN Light and Lighting -Lighting of Work Places - Part 1: Indoor Work Places defines lighting requirements that should be followed in order to obtain proper lighting solutions and gives guidance on visual comfort conditions for different space types. This standard specifies requirements for lighting solutions in retail spaces and their associated areas in terms of quantity and quality of illumination as well as giving recommendations for better lighting practice [EN 12464, 2011]. 3

4 According to the Society of Light and Lighting Handbook, lighting has four major roles in retail premises: to attract attention, to send a message to shoppers about the atmosphere of the shop, to guide shoppers around the shop to display the merchandise to advantage [Society of Light and Lighting, 2009]. The IESNA Lighting Handbook states that lighting for retail spaces should: help to create an atmosphere emphasizing the store's character, make a desirable place in which to shop, permit easy, accurate examination of the features and qualities of the merchandise, minimize glare and harsh brightness differences [IESNA, 2011]. Karlen & Benya specifies the role of lighting in retail environments as follows: to attract the eye, to illuminate the merchandise, to excite the shopper, to illuminate the work of storekeeping (including stocking, cleaning, and point of sale) to reinforce the shopper s sense of value and price point [Karlen & Benya, 2004]. In the guide to retail lighting of Building Research Establishment (BRE), Ticleanu, Littlefair & Howlett specify the factors to be considered in retail lighting design as such: Appearance of the space, people and objects Branding Visual comfort, health and well-being Energy and running costs Reliability and maintenance Flexibility Capital and installation costs [Ticleanu, Littlefair & Howlett, 2013]. There are four layers of lighting used in retail lighting: General lighting Task lighting Accent lighting Decorative - signage lighting It is clear that there are several parameters to be borne in mind in order to perform a holistic lighting design approach for retail environments. In consideration of the above given information on retail lighting design recommendations, this study aims to focus on developing a human centric sustainable retail lighting design and obtain a holistic retail lighting design approach. The application of the developed strategy is performed on the example of a selected retail environment and diverse lighting design alternatives are compared on an experimental basis. 4

5 1.1.1 Visual Comfort Criteria in Retail Lighting Design Criteria for visual comfort conditions can be investigated in the following aspects for retail environments: Illuminance levels, Uniformity, Luminances Colour. Illuminance levels: Maintained illuminance level for retail environments differ according to the type of the retail environment. Therefore, lighting design of each retail environment should be performed considering the specific retail environment s requirements and the shop profile. EN Standard gives recommendations on required illuminance for sales areas, till areas and wrapper tables [BS EN :2011]. In SLL Lighting Handbook, illuminance recommendations for retail environments are given depending on the shop profile and in The IESNA Lighting Handbook: Reference & Application, space by space classification is performed. Illuminance criteria in EN :2011, SLL Lighting Handbook and The IESNA Lighting Handbook: Reference & Application are presented in Table 2. Table 2. Illuminance criteria for retail environments EN Standard E m (lx) Sales area 300 Till area 500 Wrapper table 500 SLL Lighting Handbook E m range (lx) budget shops (without accent or 500 to 1000 lx. display lighting) shop with an exclusive profile 100 to 200 lx. (widespread use of accent and display lighting) shops with value for money and 250 to 500 lx quality profiles (with accent lighting) IESNA Lighting Handbook Horizontal Illuminance E h Vertical Illuminance Visual age of Visual age of observers observers Retail by Classification: < >65 < >65 Department store (general retail) E v Uniformity: The uniformity is defined as the ratio of the minimum to average illuminance. Uniformity is required in order to supply the visual comfort conditions in spaces and control the occurrence of high contrasts on the interior surfaces. The uniformity criteria given in Table 3 should be fulfilled for the retail environments in order to obtain visually pleasing environments. 5

6 Table 3. Uniformity criteria for retail environments EN Standard U O Sales area 0,4 Till area 0,6 Wrapper table 0,6 SLL Lighting Handbook General recommendation (Regardless of the shop profile) U O at least 0.7 IESNA Lighting Handbook (for several shop types) U O Department store (general retail) 0,33-0,66 Luminances: The luminance distribution in the visual field controls the adaptation level of the eyes, which affects task visibility. Therefore, a well balanced adaptation luminance is required in order to increase visual acuity (sharpness of vision); contrast sensitivity (discrimination of small relative luminance differences); efficiency of the ocular functions (such as accommodation, convergence, pupillary contraction, eye movements, etc.) [EN 12464, 2011]. For retail environments, luminance distribution is very effective on the strength of accent lighting where different sorts of luminance ratios can result in diverse strength of accenting. Table 4 gives the luminance ratio and the strength of accent lighting for retail environments [Society of Light and Lighting, 2009]. Table 4. The influence of luminance ratio on the strength of accent lighting [SLL, 2009]. Luminance ratio (accent/background) 1 None 2 Noticeable Strength of accenting 5 Low theatrical 15 Theatrical 30 Dramatic > 50 Very dramatic The luminance distribution in the visual field affects visual comfort conditions. In the lighting design of retail environments, control of glare is a necessity in order to perform the required visual comfort conditions. Glare is the sensation produced by a sufficiently greater luminance within the visual field causing annoyance, discomfort or 6

7 loss in visual performance and visibility [IESNA, 2011]. The assessment of discomfort glare caused directly from the artificial lighting system can be performed using the CIE Unified Glare Rating (UGR) method for the typical field of view directions in the retail space. Maximum UGR limits are given in the standards for different applications and they typically range from 19 to 22 in EN standard for retail environments. Table 5 gives the UGR criteria values given in EN Standard [EN 12464, 2011]. Table 5. Recommended UGR L values for retail environments [EN 12464, 2011]. EN Standard UGR L Sales area 22 Till area 19 Wrapper table 19 When the glare source is natural lighting, there are other methods available for the prediction of discomfort glare caused by daylight. Daylight Glare Index (DGI) and Daylight Glare Probability (DGP) metrics are examples to these methods. Colour: In the lighting design phase for retail environments, the following aspects should be considered in terms of colour: Colour Temperature and Correlated Colour Temparature (CCT), Colour Rendition, Finishing Material s Color Specifications, Colour Considerations. Colour temperature selection depends on classification of retailer, quality of merchandise, client preference and designer preference [IESNA, 2011]. It is common that the colour appearance of the light sources used in retail environments change from cool to warm as the shop profile moves from low budget to exclusive [Ticleanu, Littlefair & Howlett G., 2013]. The correlated colour temperature (CCT) of a light source determines whether it looks warm or cool. As for colour appearance, a light source with a correlated colour temperature (CCT) 3000 K will appear warm and if it has a CCT 5300 K it will appear cool, if the CCT is in between 3300 and 5300, it is considered intermediate [Society of Light and Lighting, 2009, EN 12464, 2011]. To provide an objective indication of the colour rendering properties of a light source the general colour rendering index Ra is used, having a maximum value of 100. The minimum value of colour rendering index given in lighting standards and international lighting recommendations for retail environments is 80 (See Table 6) but this value can be higher when colour judgment is crucial. 7

8 Table 6. Colour rendering index criteria for retail environments EN Standard Ra (min) Sales area 80 Till area 80 Wrapper table 80 SLL Lighting Handbook Ra (min) General recommendation 80 IESNA Lighting Handbook General recommendation (Regardless of the shop profile) Ra (min) 80 Colour considerations are determined by the nature and the special properties of the displayed merchandise, also the branding characteristics. The color parameter is also a factor, affecting the lighting performance especially in the finishing material selection phase. In other words, the light reflectance value of the surface materials should be selected studiously. The ranges of useful reflectances for the major interior surfaces are 70% - 90% for ceiling, 50% - 80% for wall, 20% - 40% for floor [EN 12464, 2011] Energy Efficiency Criteria in Retail Lighting Design Lighting design phase should represent a major route to reducing lighting energy consumption and CO 2 emissions of buildings. It is known that the retail sector consumes significant portion of the energy used in the buildings so it is important to minimise the lighting energy requirements in retail environments, starting from the lighting design phase. In Europe, The Energy Performance of Buildings Directive (EPBD) 2002/91/EC requires all EU countries to enhance their building regulations in order to monitor and reduce energy consumption. Additionally, recent EPBD Recast 2010/31/EU Directive is aimed at building professionals to design or renovate buildings to a nearly zero energy use state [European Commission, Directive 2010/31/EU, 2010]. Energy performance assessment of buildings in Europe is performed using several methodologies in the frame of the developed standards. On the other hand, advanced simulation-based energy analyses are effective in determining the lighting energy performance of buildings accurately and practically. EN Energy Performance of Buildings - Energy Requirements for Lighting Standard specifies a calculation methodology for evaluation of the amount of energy used for indoor lighting inside the building and provides a numerical indicator for certification purposes [EN 15193, 2007]. To quantify lighting energy use, the EN standard specifies a calculation 8

9 methodology for the Lighting Energy Numeric Indicator (LENI) in buildings, which can be used for existing buildings and for the design of new or renovated buildings. In this standard, the LENI limiting values are given for the retail buildings considering the lighting design criteria class in kwh/m 2 (See Table 7). Table 7. Standard sets benchmark values and lighting design criteria for retail lighting in terms of lighting design criteria classes [EN 15193, 2007]. Lighting design criteria class for retail environments LENI Limiting Value (without constant illuminance control system) LENI Limiting Value (with constant illuminance control system) basic fulfilment of requirements good fulfilment of requirements comprehensive fulfilment of requirements Sustainability and Cost Efficiency in Retail Lighting Design There is a close interaction between energy minimization in buildings and environmentally responsive, sustainable, cost effective building design. Ensuring environmental consciousness from the lighting design to postoccupancy phase is substantially crucial. Today, there are several environmental assessment systems and tools, developed to determine the environmental performance of buildings as well as building sub-systems where lighting is one of them. When designing a building, a building system or a building element, life cycle-based approaches in the material selection phase play an increasingly significant role for setting performance criteria within methods of assessment for environmental performance of buildings [ISO , 2010]. Lighting systems that are used in buildings are part of buildings sub systems and special attention should be paid for selecting the most appropriate solutions in terms of environmental consciousness. The artificial lighting products that are used in the lighting design are recommended to have Environmental Product Declaration Documentations so that the overall effects of these products can be predicted. It is only possible to determine an artificial lighting system s environmental assessment if the components of the lighting design element are known in detail. Economics is another consideration playing a significant role in architectural lighting design process, therefore the architectural lighting design stage should include the cost optimality evaluations. Lighting costs are a major concern for the designers, clients or end users and they include the investment costs, replacement costs, running and energy costs, which should be considered in terms of life cycle costing so that an optimum lighting design 9

10 solution can be obtained. A strategy for cost optimality should be followed during the architectural lighting design stage of retail environments [Yılmaz, F. Ş, 2014]. There are several financial analysis methods permitting the lighting designers or clients to evaluate and decide on the best lighting design decision [SSL, 2012; IESNA, 2011]. Currently, the Directive 2010/31/EU (recast) proposes all EU Member States to perform analysis on cost optimal levels of minimum energy performance requirements in buildings to ensure minimum energy performance requirements and achieve cost- optimal levels [EPBD recast, Directive 2010/31/EU, 2010]. The main objective of this directive is to define a comparative methodology framework for calculating cost-optimal levels of minimum energy requirements for buildings or building sub-systems. In 2012, this methodology framework was published as Commission delegated Regulation supplementing Directive 2010/31/EU in order to control lifecycle cost of buildings while minimizing their energy consumption [Commission Delegated Regulation EU No 244/2012, 2012]. Accordingly, this regulation encourages the use of EN Economic evaluation procedure for energy systems in buildings Standard to calculate total global costs in terms of net present value for building sub-systems [EN 15459, 2007]. This methodology can be implemented to retail lighting design stage in conjunction with current EN standards on buildings. 2 STEPS OF THE HUMAN-CENTRIC SUSTAINABLE RETAIL LIGHTING DESIGN APPROACH The methodology of this research involves 6 iterative steps as follows: 2.1 Step 1. Literature research Performing a detailed literature review, the research gap in human- centric sustainable lighting design approach is underlined on the strength of the advances in standards and regulations regarding visual comfort, energy efficiency, environmental impact and optimum cost considerations. Performed literature research is submitted in the 3-month progress report. 2.2 Step 2. Preparation of human- centric sustainable retail lighting design criteria matrices Introducing the criteria for retail lighting requirements on the scope of current building standards and regulations, preparation of lighting design matrices for parameters effecting human- centric sustainable lighting design is performed. The retail lighting design criteria matrices are aimed to set the benchmark values in terms of visual comfort conditions and energy requirements for retail environments. These matrices include criteria related with illuminance, luminance distribution, unified glare rating, uniformity, colour temperature, color rendering index, balance of general lighting and accent lighting. 2.3 Step 3. Development of lighting design alternative sets Based on the lighting design matrices, development of lighting design alternative sets are performed on a sample retail environment. Selected space type is a hypothetical department store clothes shop having a shop type of 10

11 shops with value for money and quality profiles. The space has dimensions of 10 m x 15 m and a height of 3.5 m. Light reflectance of the selected space are 70% for ceiling, 50%, for walls and 20% - for floor. The space has a total area of 150 m 2 containing sales area, till area, four fitting rooms and a storage room. This space is assumed to be situated in a shopping mall in Istanbul without direct access to daylighting. Figure 1 shows the plan layout (Figure 1.a) and two sections (Figure 1. b, c) and a model (Figure 1. d) of the investigated space. Figure 1. Plan, sections and model of the investigated department store Different artificial lighting system patterns are considered in this study depending on the use of general lighting, general and accent lighting, accent lighting. In this regard, 8 different layouts are generated depending on the use of most frequently observed lighting system installations in clothes shop retail environments with value for money and quality profiles. These lighting design patterns are illustrated in Figure 2. 11

12 Group A- Use of general Group B- Use of general Group C- Use of accent lighting o nly general a nd a ccent l ighting lighting o nly A1 B1 C1 A2 B2 A3 B3 C2 Figure 2. Illustration of lighting design patterns investigated in this study The retail lighting design alternative sets include use of different electric lighting strategies (use of different types of lamps, luminaires, general, accent and display lighting scenarios) and application of different physical design parameters (surface colors and materials under different lighting arrangements) for the selected retail environment. Each design alternatives is modelled on a computational basis and representative visualisations of each lighting design alternative are generated in a CIE-accredited lighting simulation software in order to further assess the user preferences (for Step 5) in retail environments. 2.4 Step 4. Performance Determination of Lighting Design Alternatives Performance determination of evaluated lighting design alternatives are performed in terms of visual comfort conditions and lighting energy efficiency. Visual comfort performance determination of the investigated department store is performed considering the benchmark values specified in EN Standard and IESNA recommendations. In order to assess the visual comfort conditions, the baseline scenarios and lighting retrofit alternatives are modelled. In this part of the study, assessment of horizontal and vertical illuminance (E), uniformity (U o ), glare caused by light sources- Unified Glare Rating (UGR) and colour property of the space and light sources are evaluated. Lighting energy performance evaluation is performed based on the LENI approach defined in EN The results obtained for this part of the study are published in A/Z: ITU Journal of Faculty of Architecture as an article entitled Energy efficient 12

13 lighting system retrofit for retail environments in Volume 13 Issue: 1 March 2016 [Yılmaz F. Ş., 2016]. 2.5 Step 5. Experimental tests: Survey-based data collection and analysis This experimental study focuses on collecting data for user preferences in retail environments. Starting from a survey, data collection on the role of humancentric sustainable retail lighting design parameters is performed. In this part of the study, the lighting design alternatives are introduced on 40 participants, equally distributed in gender. In Table 8, information on the participants, their shopping frequency and shopping priority are given. Table 8. Information on the participants, their shopping frequency and shopping priority Age: Gender: 20 female, 20 male Education level: High school and university degree Dressing style in daily life: 38% Casual, 20% Smart, 42% Smart casual Shopping frequency: Once a week: 0% Once a month: 38% 2-3 times in a month: 25% 2-3 times in a year: 22% 4-5 times in a year: 15% Shopping priority: Product quality only: 52,5% Price only: 22,5% Brand only: 15% Product quality and price: 5% Product quality and brand: 5% Pre-screening results In the survey, the opinions of the participants about the importance of physical comfort conditions (thermal comfort, visual comfort, acoustic comfort, ventilation and oldfactory comfort) for retail environments is questioned on a scale of 1 to 5, 5 representing very important and 1 being less important. 80% of the participants stated that visual comfort conditions are of high importance. When the importance of an appropriate lighting system design is questioned for shopping areas (showcases, sales areas, fitting rooms and till areas), showcases and fitting rooms are found to be of high importance in terms of lighting design with 80%, which is followed by sales areas (75% high importance). Figure 3 represents the graphical distribution of obtained results for importance of an appropriate lighting system design for diverse shopping areas. 13

14 (%)# 100) 90) 80) 70) 60) 50) 40) 30) 20) 10) 0) 80# Showcases) Sales)areas) Fi.ng)rooms) Till)areas) low)importance) 15) 5) 2,5) 50) middle)importance) 5) 20) 17,5) 37,5) high)importance) 80) 75) 80) 12,5) 75# 80# 12,5# Figure 3. Results for importance of an appropriate lighting system design for shopping areas The expectations of the participants from lighting system design in shopping areas is questioned in terms of illuminance level, control of glare, accurate color perception, uniformity of lighting and use of daylighting. Obtained results show that accurate color perception is found of high importance, which is followed by adequate illuminance level, control of glare and uniformity of lighting. Use of daylighting is only found of high importance with a percentage of 25%. In Figure 4, distribution of obtained results for the expectations of the participants from lighting system design in shopping areas is given in a graphical expression. (%)% 100* 90* 80* 70* 60* 50* 40* 30* 20* 10* 0* 92,5% Illuminance* level* 72,5% Control*of* glare* 97,5% Accurate* color* percep4on* 62,5% Uniformity*of* ligh4ng* Use*of* dayligh4ng* low*importance* 0* 10* 2,5* 12,5* 55* middle*importance* 7,5* 17,5* 0* 25* 20* high*importance* 92,5* 72,5* 97,5* 62,5* 25* 25% Figure 4. Obtained results for the expectations of the participants from lighting system design in shopping areas Survey-based data collection and analysis for retail lighting design alternatives A survey is applied for each participant, and their feedback on obtained diverse retail lighting design alternatives (described in Step 3) is collected. The outputs 14

15 of the experimental analysis are investigated in terms of space-based and merchandise-based questions. Participants opinion on the success of performed lighting design alternative, their price expectation and their quality expectation for the products in the evaluated retail space are collected. Statistical analysis of the test results are performed. Obtained data is aimed to be used for development of the human centric sustainable retail lighting design approach Comparison of lighting design alternatives with the use of general lighting only (A1, A2, A3) and use of general and accent lighting (B1, B2, B3) In this part of the study, participants feedback on obtained diverse retail lighting design alternatives with general lighting only (A1, A2, A3) and use of general and accent lighting (B1, B2, B3) are collected. Illustrations representing the compared alternatives are given in Table 9. Table 9. Lighting design alternatives with the use of general lighting only (A1, A2, A3) and use of general and accent lighting (B1, B2, B3) Group A - U se o f g eneral l ighting o nly Group B- Use of general general and accent lighting A1- use of square - recessed luminaires B1- use of square - recessed luminaires and only spotlights A2- use of circular recessed downlight B2- use of circular recessed downlight luminaires o nly luminaires A3- u se o f l inear - r ecessed l uminaires o nly B3- use of linear - recessed luminaires and covelighting 15

16 When the feedback of participants are investigated in terms of success of performed lighting design alternative, participant s price and quality expectations for the evaluated retail space, it is found that use of accent lighting together with general lighting positively effects the participants opinion on success of lighting design for the investigated space and it significantly increases their price expectation for the products while their expectation on the quality of products slightly increases. Figure 5 gives the average of the results obtained for the comparison of Group A (use of general lighting only) and Group B (use of general and accent lighting) in terms of participants opinion on the success of performed lighting design alternative, their price expectation and their quality expectation for the products Lighting design Unsuccessfull AV_A1-A2-A3 AV_B1-B2-B3 Successfull Price expectation for products Cheap AV_A1-A2-A3 AV_B1-B2-B3 Expensive Quality expectation for products Low quality AV_A1-A2-A3 AV_B1-B2-B3 High quality Figure 5. Graphical distribution of obtained results for Group A and Group B in terms of participants opinion on the success of performed lighting design alternative, their price expectation and their quality expectation for the products. 16

17 Comparison of lighting plan settings with the use of general lighting only (A1, A2, A3) and use of accent lighting only (C1, C2) In this part of the study, participants feedback on obtained diverse retail lighting design alternatives settings with general lighting only (A1, A2, A3) and use of accent lighting only (C1, C2) are collected. In Group C, use of accent lighting only is investigated for two different lighting alternatives- C1 and C2. In C1, a retail lighting design with the use of spotlights mounted on tracks is considered while in alternative C2, spotlights are mounted on the suspended ceiling. Illustrations representing the compared alternatives are given in Table 10. Table 10. Lighting plan settings with general lighting only (A1, A2, A3) and use of accent lighting only (C1, C2) Group A - U se o f g eneral l ighting o nly Group C - U se o f a ccent l ighting o nly A1- use of square - recessed luminaires C1- u se o f s potlights m ounted o n t racks only A2- use of circular recessed downlight C2- u se o f s potlights m ounted o n c eiling luminaires o nly A3- u se o f l inear - r ecessed l uminaires o nly When the feedback of participants are investigated in terms of success of performed lighting design alternative, participant s price and quality expectations for the evaluated retail space, it is found that use of accent lighting only positively effects the participants opinion on success of lighting design for the investigated space and it significantly increases their price and quality expectation for the products when compared with the results obtained for the use of general lighting only. In Figure 6, a graphical expression of the 17

18 results obtained for Group C compared with the average of obtained results for Group A1 (use of general lighting only) is given. 100$ 80$ 60$ Ligh%ng'design' 46$ 45$ 40$ 35$ 37,5$ 28$ 20$ 22,5$ 17,5$ 18$ 17,5$ 12,5$ 7,5$ 2,5$ 0$ 3$ 0$ 1$ 2$ 3$ 4$ 5$ Unsuccessfull Successfull C1$ C2$ Avg_A11A21A3$ Price&expecta+on&for&products&& 100$ 80$ 60$ 62,5$ 40$ 43$ 47,5$ 30$ 32$ 20$ 22,5$ 17$ 20$ 12,5$ 3$ 2,5$ 6$ 0$ 0$ 0$ 1$ 2$ 3$ 4$ 5$ Cheap C1$ C2$ AV_A10A20A3$ Expensive $ $ $ 100$ 80$ 60$ 40$ 20$ Quality&expecta+on&for&products&& 21$ 42$ 32,5$ 47,5$ 17,5$ 0$ 2,5$ 1$ 0$ 3$ 0$ 1$ 2$ 3$ 4$ 5$ e Low quality High quality C1$ C2$ AV_A10A20A3$ 33$ Figure 6. Graphical distribution of obtained results for Group C and Group A in terms of participants opinion on the success of performed lighting design alternative, their price expectation and their quality expectation for the products. 18

19 2.5.3 Discussion of results There are many parameters effecting human s perception in retail environments where lighting design is one of them. This study aims to investigate human s preferences in retail environments under diverse lighting design alternatives for a selected retail case study. Evaluated space is modelled using an accredited lighting simulation program, images representing different lighting design options are generated and human s preferences for each lighting design option is collected by the help of an applied survey. In this study, three lighting design categories are considered: Group A- use of general lighting, Group B- use of general and accent lighting and Group C: use of accent lighting only. In each group, several lighting design configurations are generated that are representative of each lighting design pattern and a number of 8 different cases are evaluated. It is clear from the obtained results that with the use of an appropriate lighting design strategy, it is possible increase the positive impact of lighting design on the users. Obtained results also show that use of accent lighting strategy increases the user s expectations in terms of product price and quality therefore it is found in this study that lighting design in retail environments has a direct impact on the customer s space perception. Using an appropriate accent lighting strategy is found to attract customers and create the right atmosphere for the selling products. 3 CONCLUSION This document represents the summary of final results for SLL-Jean Heap Research Bursary The duration of the research project entitled Humancentric sustainable retail lighting design approach: An experimental study was 12 months and the study was conducted at Istanbul Technical University Faculty of Architecture by the support of Society of Light and Lighting. During this project, progress reports and presentations had been performed in each 3 months and the first findings of the study were presented in November at LuxLive Final presentation of the research project is performed at 2016 SLL AGM in May This research aims to underline the significance and benefits of human centric sustainable retail lighting design and as part of this research, a human centric sustainable retail lighting design approach is aimed to be obtained. The proposed lighting design approach in this study can be used in the retail lighting design practice. The aim of this study is to evaluate the user s perspectives on retail lighting design for a sample space type. This study is limited to one type of retail environment- a cloth s store but the research can further be extended to consider different types of retail environments in the future. The experimental part of this study is performed by survey-based data collection which is applied for 40 participants aged between 20 and 36, equally distributed in gender. As a future study, diverse age groups and socio-cultural groups can also be considered in order to fully investigate the impact of human perspectives on retail lighting design. 19

20 Results and benefits of this research are to provide practical retail lighting design guidance to retailers, architects and lighting designers in order to refurbish existing lighting schemes and develop new lighting design solutions considering a holistic experimental approach. 4 REFERENCES British Standards Institution (2011). Light and Lighting. Lighting of Work Places- Indoor Work Places. BS EN :2011. London: British Standards Institution. Commission Delegated Regulation (EU) No 244/ January 2012 Supplementing Directive 2010/31/EU of the European Parliament and of the Council on the energy performance of buildings by establishing a comparative methodology framework for calculating cost-optimal levels of minimum energy performance requirements for buildings and building elements, Official Journal of the European Union. EN (2007). Energy performance of buildings - Economic evaluation procedure for energy systems in buildings, European Committee for Standardisation. European Commission, Directive 2010/31/EU (2010), Directive of the European Parliament and of the Council of 19 May 2010 on the Energy Performance of Buildings (Recast), Brussels: EC European Committee for Standardization (2007), EN 15193: Energy Performance of Buildings-Energy Requirements for Lighting, Brussels: CEN European Committee for Standardization (2011). EN : Light and Lighting: Lighting of Work Places - Indoor Work Places, Brussels: CEN. IESNA The IESNA Lighting Handbook: Reference & Application. 10th Edition. Illuminating Engineering Society of North America, New York. ISO :2010, Sustainability in Building Construction Framework for Methods of Assessment of the Environmental Performance of Construction Works Part 1: Buildings. Karlen M., Benya J. (2004) Lighting Design Basics, John Wiley & Sons, USA Society of Light and Lighting (2009) The SLL lighting handbook. London: Chartered Institution of Building Services Engineers Society of Light and Lighting (2012) The SLL Code for Lighting. London: Chartered Institution of Building Services Engineers Ticleanu C., Littlefair P.J., Howlett G. (2013) The Essential Guide to Retail Lighting, IHS BRE Press, ISBN: Yılmaz, F. Ş. (2014). An Architectural Lighting System Design Approach for Sustainable Environments (PhD Disseration). İstanbul Technical University, Institute of Science and Technology, İstanbul. Yılmaz, F. Ş. (2016) Energy efficient lighting system retrofit for retail environments, A/Z: ITU Journal of Faculty of Architecture, Volume 13 Issue: 1,