A Human-Centric Qualitative Analysis of Electric and Daylighting Interventions in Workplace Buildings

*Abimbola O. Asojo, Hoa Vo and Suyeon Bae* 

#### **Abstract**

Current literature highlights the importance of human-centric lighting (HCL) design interventions in the built environment that move beyond energy-centric approaches and focus on occupant satisfaction, health, and well-being. A Midwest University interdisciplinary team conducts an evidence-based analysis of occupants' satisfaction, health, and well-being in state-funded buildings using the Sustainable post-occupancy evaluation survey (SPOES) and provides suggestions for improvements. SPOES is an online-administered questionnaire with a sevenpoint satisfaction-Likert-scale (very dissatisfied to very satisfied) and open-ended questions regarding occupants' satisfaction with indoor environmental quality (IEQ ) factors including daylighting and electric lighting. The authors present a thematic qualitative analysis of the impact of daylighting and electric lighting on occupants (N = 2690) in 13 workplace buildings surveyed from 2009 to 2017. Three themes were derived from the data. First, *insufficient access to daylighting and view*, respondents reported the lack of daylight and outdoor views due to isolated office-spaces and lack of windows. Second, *inadequate control of electric lighting*, respondents reported automatic lighting systems failed to meet task-specific needs while demanding excessive adjustments. Third, *poor integration between daylighting and electric lighting*, respondents preferred warmer color temperature lighting to cooler fluorescent lighting and reported amount of contrasts between daylighting and electric lighting caused eyestrains and migraines.

**Keywords:** human-centric, daylighting, electric lighting, well-being, workplace

#### **1. Introduction**

Human-centric lighting (HCL) is an approach to lighting that considers occupants' needs for visuality, biology, and emotion in design [1]. In technical terms, HCL involves daylighting and dimmable electric lighting with large warm-to-cool color-changing-range (i.e., tunable LED). Especially, researchers at Harvard School of Medicine formed the Human Centric Lighting Committee as a way to acknowledge the significance of HCL to human well-being [2]. Current literature also highlights the importance of HCL design interventions in the built environment that move beyond energy-centric approaches and focus on

 occupants' satisfaction, health, and well-being [3]. General concerns for the lack of HCL design interventions include disturbed circadian rhythm, affected mood, reduced visual acuity, and declined productivity. While changes in dopamine, serotonin, and cortisol lead to these negative impacts, the indoor lighting patterns that influence human metabolism should be held accountable [4]. A University of Minnesota interdisciplinary team, hence, conducts an evidence-based analysis of occupants' satisfaction/visuality, health/biology, and well-being/emotion in state-funded buildings using the Sustainable post-occupancy evaluation survey (SPOES) and provides suggestions for improvements in the built environment. The team focuses on the workplace where HCL-related concerns found in the literature review are most prominent. Overall, the findings resonate well with the literature on human-centric lighting design, which reinforces the importance of daylighting accessibility, personal-adjustability of lighting conditions, and integration of daylighting and electric lighting [5–8]. This chapter discusses the data-driven themes and explores potential HCL remedies to improve satisfaction and efficiency in the workplace.

#### **2. Background—sustainable post-occupancy evaluation survey**

 Historically, humans spent 90% of their time outdoors with high daylightingexposure. More recently, humans now spend 90% of time indoor with major electric-lighting-exposure. This change has disrupted humans (building occupants) from the ever-changing intensity and correlated color temperature (CCT) of sunlight (**Figure 1**). The human body is responsive to sky-reflected-daylight at 10,000 K and above which evoke dopamine, serotonin, and cortisol while controling melatonin. In short, human stays awake, attentive, and productive instead of relaxing and sleeping. A general rule is to aim for higher correlated color tempature (CCT) while designing electric lighting. Nevertheless, indoor lighting deviates from the variances in CCT of daylighting. HCL design interventions, thus, are task-driven, environment- and time-dependent not just specifying illuminance and CCT. A checklist for designing HCL interventions includes task-related demands, spatial conditions, architectural restrictions, occupants' professional, physiological, and psychological needs. Once implemented, instructions for operating HCL interventions should be available for the occupants to access [1, 4, 9].

Electric lighting uniformity in common practice also discourages photosensitive retinal ganglion cells (ipRGC), thus reduces alertness and productivity. In the workplaces, which value these abilities, this fact is a major concern. As architects and interior designers reinvent the workplace, they are acknowledging "we've forgotten that we're designing for people" and directed attention to human-centric and data-driven applications of electric lighting [10]. Designers and architects should expand their focus beyond energy-centric concerns to a broader perspective of occupants' life quality, satisfaction, and psycho-physiological well-being. Therefore, they need to take into consideration the "ingredients of human-driven design" such as individual preferences for daylighting in terms of physiology, diurnal circle, seasons, and other demographic elements (i.e., culture, social contexts, etc.) [11].

**Figure 1.** 

*Human circadian rhythm in terms of light intensity and CCT. Authors created based on [1].* 

*A Human-Centric Qualitative Analysis of Electric and Daylighting Interventions in Workplace… DOI: http://dx.doi.org/10.5772/intechopen.87836* 

A 2011 workplace survey of Union Investment—German financial cooperation, showed lighting as the top priority to occupants. Acoustic, technology, indoor climate, ergonomic furniture, ventilation, and decoration came after, repsectively. One of the prominent approaches to HCL is giving occupants in workplace control over electric lighting. Being able to adjust the direction, intensity, and tone evokes positive emotion, improve satisfaction and productivity. Manufacturers like Philips, the eminent Dutch electric company, offer dimmable warm-white-light fluorescent lamps that mimics daylight. They suggested CCT is 5000–6500 K instead of the traditional 3000–3500 K. For LED lamps, the range is 6000–8000 K to reproduce the blue-content of daylight reflected from the sky. These manufacturers' approaches, however, have not gone under the peer-reviewed-process, thus need further support for their stand over common practices [2, 12].

 Cognitive test and surveys taken by occupants in 10 office buildings in 5 cities in the United States (n = 109) revealed insights regarding occupant health and environmental perceptions. Improvements in indoor environmental quality (IEQ ) categories associated with better health outcomes. In green-certified buildings (i.e., high-rated IEQ categories), occupants outperformed on cognitive function tests (with annual earnings, job category, and level of schooling controlled) and reduced in sick building symptoms than those in non-certified buildings. Among measurable IEQ factors, the benefits of lighting stood out. Daylighting and electrical light quality in green-certified buildings helped occupants have better sleep and cognitive function scores [13]. Data collection instruments such as Sustainable postoccupancy evaluation survey (SPOES), hence, become important. IEQ study with participants in Spain, Greece, Italy, Portugal, Finland, France, Hungary, and The Netherlands (n = 6116) found that lighting was highly associated with occupants' comfort. The implication was a mindful consideration of occupant and building characteristics to create a healthier and more comfortable workplace. Occupants' perception of indoor lighting conditions affected their comfort, and consequently their health, well-being, and productivity. Thus, they provided the best information for occupant needs and comfort requirements. Findings indicated natural light was the foremost factor contributing to light quality followed by artificial light and glare. Especially, level of daylight in the workplace helped improve occupants' comfort and mood while appropriate amount of electric light determined visual acuity. However, providing healthy and comfortable light in the workplace remains a challenge [14].

 Developed by a University of Minnesota interdisciplinary team, SPOES assesses occupants' satisfaction in buildings, recognizes effective interventions, and guides improvements with data-driven evidence. SPOES is an Internet-based questionnaire administered via Qualtrics. From 2009 to 2017, SPOES has collected data from occupants (N = 4205) in 43 buildings including workplaces (i.e., offices), classrooms, and residence halls. All complied to the B3 benchmark program which promotes sustainable design and energy efficiency in State-funded buildings in Minnesota. This chapter only discusses the SPOES results in 13 workplace-buildings (N = 2690). For instance, Clinics and Surgery Center (CSC) of University of Minnesota Physicians (UMP) (**Figure 2**), is a five-story, 332,240 gross square feet building of clinics, outpatient surgery, and cancer treatment areas. The staff included medical, human resource, facility, maintenance, and support personnel. Data collection centered in the primary workspaces of private and shared touchdown spaces, collaboration spaces, nursing stations, sessioning areas, reception areas, concierge area, control areas, etc. Another example was North Hennepin Community College, Bio-Sciences and Health Careers Center (NHCC-BHCC) (**Figure 3**), a two-story 64,284 square feet building that includes classrooms, laboratories, and offices. Data collection focused on the 3940 square foot workplace

**Figure 2.**  *University of Minnesota Physicians (UMP), Clinics and Surgery Center (CSC), Image © UMP.* 

#### **Figure 3.**

*North Hennepin Community College, Bio-Sciences and Health Careers Center (NHCC-BHCC), Photography 2014 © Corey Gaffer, Perkins + Will.* 

with private offices, enclosed shared offices, workstations of low/high-partition cubicles, no-partition desks in open areas, and lab work areas. Designated tasks of the staff were administrative and academic support to students.

 SPOES identifies IEQ categories that contribute to occupant satisfaction, health and well-being such as acoustic conditions, indoor air quality, personal adjustability, daylighting, and electric lighting. Occupants' responses reflected their perception of the building's physical environment on their work performance and health.

*A Human-Centric Qualitative Analysis of Electric and Daylighting Interventions in Workplace… DOI: http://dx.doi.org/10.5772/intechopen.87836* 

Lighting, among other IEQ categories, is highly predictive for occupants' satisfaction and performance. Each IEQ category consists of two levels of criteria: an overall one and correspondent specific attributes. SPOES addresses both overall daylighting condition and overall electric light condition. Correspondent attributes are as follow amount and adjustability of daylighting; amount and adjustability of general and task-based electric lighting. All categorical items in SPOES questionnaire has been tested for validity (the extend to which data supports result-interpetations) and reliability (consistency of findings).

#### **3. Data collection**

 The authors present the thematic qualitative analysis of occupants (N = 2690) in 13 workplace buildings and discuss the impact of daylighting and electric lighting on occupants' satisfaction, health, and well-being. In the SPOES Qualtrics questionnaire, occupants used a Likert-type scale from 1 (very dissatisfied) to 7 (very satisfied) to rate their level of satisfaction of their workplace regarding 12 IEQ categories. The IEQ categories are acoustic quality, appearance, cleaning and maintenance, daylighting conditions, electric lighting conditions, furnishings, indoor air quality, privacy, technology, therma conditions, vibraton and movement, and view conditions. This chapter focuses only on daylighting and electric lighting. Occupants also rated the influence of physical workplace environment on their performance and health from 1 (hinders) to 7 (enhances). Furthermore, there were open-ended questions regarding their satisfaction with daylighting and electric lighting. Occupants, therefore, had the opportunity to raise specific concerns on the overall quality of lighting and their correspondent attributes. The authors collected occupants' open-ended responses from Qualtrics questionnaire and created a Nvivo-script-formatted Word document. Headings and word styles separated questions from responses and sorted inputs of different occupants. A total of 2441 words of the typed responses went into NVivo. To explore potential categories, the authors first run word-frequency query across the document. Words with highest frequencies and related meanings, as shown in the word cloud (**Figure 4**), became 20 categories. The authors then manually assigned related quotes to each category, analyzed similarities and differences, and grouped them into three main themes: light *accessibility*, *control*, and *integration*.

**Figure 4.**  *Word cloud for high-frequency terms in SPOES open-ended answers. Created by authors in NVivo.* 

#### **4. Findings**

The open-ended responses strongly associated with specific attributes such as the amount, color, and adjustability of daylighting and electric lighting (**Figure 5**). Below are three prominent themes that contained these attributes and selected coressponding quotes.

#### *ISBS 2019 - 4th International Sustainable Buildings Symposium*

#### **Figure 5.**

*Diagrammatic themes with quotes. Visualized by authors.* 

First, *insufficient access to daylighting and view*, respondents reported the lack of natural lighting and outdoor views due to isolated office-spaces and the absence of windows.


Second, *inadequate control of electric lighting*, respondents reported the automatic lighting systems failed to meet their task-specific needs (e.g., glare, harsh, and shadow) while demanding excessive adjustments (e.g., large movements, continuous reoperations of sensor lights).


*A Human-Centric Qualitative Analysis of Electric and Daylighting Interventions in Workplace… DOI: http://dx.doi.org/10.5772/intechopen.87836* 


 Third, *poor integration of daylighting and electric lighting*, respondents preferred warmer color temperature lighting to fluorescent lighting and reported amount of contrasts between daylighting and electric lighting caused eyestrains and migraines.

 • "I wish there were more windows, or the lighting was warmer and less fluorescent."

**Figure 6.**  *Discrepancies between daylight and electric lighting. Visualized © authors.* 


The overall finding (**Figure 6**) resonates well with the literature on HCL design interventions, which reinforces the importance of daylighting accessibility, personal-adjustability of lighting conditions, and interactions between daylighting and electric lighting [5–8].

#### **5. Conclusion**

 Current literature and SPOES findings support the importance of humancentric lighting design interventions in the built environment. Lighting is considered as the primary environmental time cue for synchronizing human circadian rhythm. Hence, there is a need to move beyond energy-centric approaches and consider daylighting and electric lighting design from the perspective of occupants' quality of life, satisfaction, and well-being. Accordingly, the built environment should be designed to support the human circadian clock through blue light exposure in the day and a reduction of blue light exposure in the evening to enrich the overall well-being and promote healthy sleep pattern, thus benefitting human health. The literature review also highlights the importance of daylighting design strategies, lighting controls and post-occupancy evaluations as the key drivers in designing HCL interventions for occupants' health and well-being in the built environment. Based on the analysis of SPOES over an 8-year-period, a future direction is to include qualitative approaches using participatory methods such as consultations, workshops, focus groups to explore occupant satisfaction, and well-being, so these findings can be used to guide policy. Another recommendation is to consider integrating physical measurements to study daylighting and electric lighting in the post-occupancy evaluation process. Additional data such about work plane illuminance; visual comfort (avoiding discomfort glare); non-visual effects of light (circadian rhythms impact and cognitive function); and occupant behavior can be collected to help inform HCL quality decisions.

#### **Acknowledgements**

 This work was supported by a United States Department of Agriculture (USDA) National Institute of Food and Agriculture (NIFA) grant and the University of Minnesota Agriculture Research and Extension (AES) program.

#### **Conflict of interest**

 The authors declared no potential conflicts of interest with respect to the authorship and/or publication of this article.

*A Human-Centric Qualitative Analysis of Electric and Daylighting Interventions in Workplace… DOI: http://dx.doi.org/10.5772/intechopen.87836* 

#### **Author details**

Abimbola O. Asojo1 \*, Hoa Vo1 and Suyeon Bae2

1 Department of Design, Housing, and Apparel, University of Minnesota, Minnesota, USA

2 Department of Architectural Studies, University of Missouri, Columbia, USA

\*Address all correspondence to: aasojo@umn.edu

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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#### **Chapter 2**
