For the past two decades, most of the sub-Saharan African countries have recorded unprecedented economic development and population growth. Because of resource constraints, these achievements have forced some countries to maximize the use of available infrastructures and resources to meet the demand of the increased population [
The advancement and wide adoption of Information Communication Technology (ICT) has made video display terminals (VDT) the standard working tools in offices [
Visual discomfort and physiological and psychological strain such as anxiety, fatigue, lethargy, headaches, eyestrain, migraine, nausea, back pain, neck pain, shoulder pain, poor concentration or lack of mental alertness, and daytime sleepiness among VDT workers are primarily connected with inadequate lighting in the working place and in most cases decrease work performance and efficiency [
The lighting illuminance level and uniformity refer to the maintained minimum average illumination required to accomplish a specific task in a given work plane [
The correlated color temperature (CCT) and color rendering index (CRI) of the light source dictate the way the light is perceived in a given space. Both CCT and CRI play a dynamic role in addressing the psychological and physiological functions of the occupant [
van Bommel [
Flicker occurs when light is modulated at lower frequencies. Flicker is common in fluorescent lamps operated on magnetic ballasts [
A large amount of research has identified that lighting also exerts nonvisual effects on biological rhythms, commonly known as body circadian cycle [
Light has a dual nature. It appears as both wave and particle, and the wavelength of light determines the color perceived by the eye. In the visible region which ranges from ≈380 nm to 780 nm [
Furthermore, epidemiological evidence demonstrates that people working in night shift works have a higher rate of cancer cases and a high rate of breast cancer among the female population, especially in the industrialized countries [
Although previous studies have clearly demonstrated that inadequate lighting environment in offices affects workers’ well-being, work productivity, and efficiency, similar studies in developing countries especially in African countries are still rare. Thus, the primary objective of this study is to analyze the effects of the office building lighting quality on working efficiency of workers in Tanzania. The research is very significant in promoting awareness and providing a contribution to the existing body of knowledge regarding the effect of inadequate lighting environment on occupants’ health, productivity, and working efficiency.
The study was conducted at MUST in Tanzania from June to September 2018. In order to elucidate the lighting scenario and its effect on occupants, four representative offices were selected based on their unique characteristics and representation merits. Their floor plans and physical features were studied as demonstrated and summarized in Table
A summary of the offices’ physical characteristics and lighting condition in the surveyed offices.
Office | Function | Parameters | Physical characteristics |
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1 | Office of Head of Department (Architecture) located in the first floor | Ceiling | Plasterboards at 3.485 m above floor painted white and decorated to matt finish hardwood |
Walls | Plastered concrete blocks painted off white | ||
Floor | Red carpet | ||
Working plane | Matt finish hardwood table, close to the window, at 0.714 m above the floor | ||
Lighting characteristics | Both naturally and artificially lit; clear glass on the window with translucent curtain, four ceiling-mounted fluorescent tubes TU and T8, 36 W, fixed on magnetic ballasts | ||
Humidity and temperature | The humidity was 65%, and the temperature was 23°C | ||
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2 | Staff’s office (Architecture Department) located in the second floor | Ceiling | Gypsum board, painted in white color |
Walls | Plastered concrete block painted in white color | ||
Floor | Cement sand screed | ||
Working plane | Mixed type of furniture, ergonomics not well adhered to | ||
Lighting characteristics | Both naturally and artificially lit, a small side window with clear glass and a translucent curtain, three surfaces mounted fluorescent tube Philips T8, 36 W fixed on a magnetic ballasts | ||
Humidity and temperature | The humidity was 70%, and the temperature was 25°C | ||
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3 | Accounting office located in the basement | Ceiling | Concrete soffit painted white at 3.213 m headroom |
Walls | Plastered and waterproofed concrete block, painted in white color | ||
Floor | White ceramic tiles | ||
Working plane | Matt and gloss finish hardwood tables at 0.75 m above the floor | ||
Lighting characteristics | Artificially lit, with a ventilation window at ceiling level supplied with mosquito gauze, two fluorescent tubes TU and T8, 36 W, fixed on magnetic ballasts and mounted on ceiling soffit | ||
Humidity and temperature | The humidity was 75%, and the temperature was 21°C | ||
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4 | Estate manager’s office located in the first floor | Ceiling | Gypsum board at 2.8 m from the floor |
Walls | Concrete blocks, plastered and painted off-white | ||
Floor | Cement sand screed | ||
Working plane | Matt and gloss finish hardwood tables at 0.75 m above the floor | ||
Lighting characteristics | Both naturally and artificially lit; clear glass on the window with translucent curtain, one pendant fluorescent tubes TU and T8, 36 W, fixed on magnetic ballasts mounted on the wall at ceiling level | ||
Humidity and temperature | The humidity was 66%, and the temperature was 23°C |
MUST is one of the oldest educational institutions in Tanzania. It was founded in 1986 as Mbeya Technical College (MTC) offering full technician certificate (FTC) education to less than 500 young Tanzanians under the Russian training support. “
The horizontal illuminance values and distribution in the selected four representative offices and indoor air quality in each office were recorded using a digital lux meter GM1040 mounted on the unique tripod stand at 0.85 m from the floor and electronic environmental meter. The room dimensions were measured using a laser distance meter, and the illuminance grid points were determined based on the room dimensions, as shown in Figure
The floor plans of the representative offices and images showing the impression of lighting set up and the equipment involved in measurements.
A set of the structured questionnaire was administered to respondents to establish their rate of satisfaction, feeling about the lighting environment, the existence of both visual and nonvisual problems in their workplace, and how these factors influenced their health and working efficiency. The questionnaire was therefore broken down into three parts, including nine questions on demographic information, twenty-eight questions about the perceived lighting quality, feelings, satisfaction, and visual annoyance, and ten questions about health issues related to lighting problems in the working environment. A Likert five-point scale system and a dichotomous two-scale system of “Yes and No” questions were applied in structured questions. Additionally, two open-ended questions were included to capture in-depth the lighting problems the users are facing in their offices. Their comments, feelings, lighting preferences, and improvement measures were also assessed. A pilot study was conducted online from March to June 2018 to test the effectiveness of the intended online questionnaire method. Twenty Ph.D. and Master’s degree students in different job categories from MUST were involved in the study. The feedback on the professionalism of the used language, length, and other ambiguities of the questionnaire were issued for the final version which was used in the survey. A simplified language was used in the questionnaire, and a short introduction was given to every section of the questionnaire for more clarity and simplicity.
All variables used in this questionnaire were primarily extracted from the existing research in most of the literature covered above. The respondents were asked several questions in order to self-evaluate themselves and report on their perceived lighting quality. Questions on illuminance level and distribution, visual comfort-ability, lighting reflections, brightness and color contrasts, glare existences and user’s perception, flicker existence, sound annoyance, and concentration or alertness were asked. Respondents were also asked to rate the attractiveness of the surrounding luminous environments and their level of satisfaction. Additionally, respondents were asked to self-report the prevalence of musculoskeletal symptoms [
All staff members (about 600 employees) at MUST were the target group in this research. A simple random sampling method was adopted in questionnaire distribution. The target sample of respondents was 240 people, determined by using Taro Yamane’s formula in the following equation:
All the data were evaluated and analyzed in the statistical package for social science (SPSS version 20), and some graphs were treated using an excel spreadsheet. Descriptive statistics tools such as percentages, frequencies, and graphical representation were applied to analyze the quantitative information. Cross tabulation and statistical tests such as one-sample
In this study, among the 171 respondents, 39.8% were female and 60.2% were male. The academic staff constituted 60.8% of all respondents, while 22.2% were management staffs, 12.3% logistics, and 4.7% were from other work categories. Age issues were also considered whereby all age groups were covered in the survey. In this regard, 12.9% of all respondents were aged between 20 and 30 years, 77.2% were aged 31–45, and 9.9% were between 46 and 60 years old. Only 2.9% of the respondents were Ph.D. holders, 21.1% were vocational and diploma certificate holders while 33.33% and 42.7% were bachelor and master’s degree holder, respectively. Furthermore, 97.7% of all respondents reported that they have been working at MUST for less than 20 years, and 2.3% have worked at MUST for more than 20 years. 80% of the respondents reported having a 5-day work per week, and the average working hours for all participants were 7.6 hours per work-day. Among all respondents, only 13.5% had a vision impairment, and most of the time, they used glasses due to myopia. Additionally, 76.6% (
Five questions were inquired of respondents to self-report their measure of perceived lighting quality and its suitability by using a five-point Likert scale ranging from 1-strongly disagree to 5-strongly agree. The descriptive statistics evaluation and one sample
Also, the relationship between variables was tested using Pearson’s coefficient at a confident level of 95% (
The correlation coefficients and significance levels between the variables for the lighting quality and its suitability.
Variables | L&D | VC | Pr | IR | Br&C | |
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Lighting level and distribution (L&D) | Pearson’s correlation | 1 | ||||
Sig. 2-tailed | ||||||
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171 | |||||
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Visual comfort (VC) | Pearson’s correlation | 0.532 |
1 | |||
Sig. 2-tailed | 0.0001 | |||||
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171 | 171 | ||||
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Precision (Pr) | Pearson’s correlation | 0.196 |
0.333 |
1 | ||
Sig. 2-tailed | 0.010 | 0.0001 | ||||
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171 | 171 | 171 | |||
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Internal reflection (IR) | Pearson’s correlation | 0.179 |
0.280 |
0.448 |
1 | |
Sig. 2-tailed | 0.019 |
0.0001 | 0.0001 |
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171 | 171 | 171 | 171 | ||
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Brightness and color contrast (Br& C) | Pearson’s correlation | 0.195 |
0.279 |
0.310 |
0.335 |
1 |
Sig. 2-tailed | 0.011 |
0.0001 | 0.0001 | 0.0001 | ||
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171 | 171 | 171 | 171 | 171 |
The measure average offices illuminance level and uniformity.
Office | Average horizontal task illuminance level (lux) | Horizontal illuminance uniformity ratio (Ehmin/Ehavg ) | Specified minimum task illuminance and uniformity | |
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RM1 | Head of the department | 196 | 0.332 | 500 lux for the tasks involving writing, reading, and typing, and 0.8 of the illuminance uniformity ratio |
Assistant Head of the department | 443 | 0.336 | ||
Secretary office | 105 | 0.524 | ||
RM2 | 84 | 0.488 | ||
RM3 | 198 | 0.747 | ||
RM4 | 193 | 0.834 |
RM = room; Ehmin = minimum desk illuminance; Ehavg = average desk illuminance.
From Table
Occupants were asked to self-report the level of comfort created by the lighting environment in their workplace by using a five-point Likert scale of agreement ranging from 1-low agreement to 5-high agreement. The results indicate that a small number of the respondents (46.2%) (
The subjective assessment of the daytime alertness and concentration among the subjects also revealed that 49.7% (
The subjective assessment using structured questionnaire under five-point Likert scale ranging from “1 =
The perceived influence of lighting environment on occupants’ health. (A) Insomnia. (B) Back pain. (C) Neck pain. (D) Shoulder pain. (E) Tiredness. (F) Sleepiness. (G) Teary eyes. (H) Headache. (I) Eyestrain. (J) Eye fatigue. (K) Stress.
For the past few decades, the advancement in information communication technology has changed the landscape of offices around the world. The wide use of VDT in the workplace has called for new office design requirements. Awareness of this scenario has been improved, and remedial actions are widely practiced in most of the developed countries and fast-developing countries. However, in most of the least developed countries, especially African countries such as Tanzania, this case is still not clear and lacks some research. Reports have indicated that poorly designed offices environments such as inadequate lighting affects human health and work performance. Based on that, this research aimed at analyzing the effects of lighting quality on working efficiency of workers in an office building in Tanzania. One office building at Mbeya University of Science and Technology was selected as a case study. Physical observation and questionnaire survey methods were employed to collect the data. The results have demonstrated that the illuminance level and uniformity in this particular workplace were inadequate and to some extent and affected the occupants’ health, work efficiency, and productivity.
Moreover, the research identified that most of the office had glare problems, flicker, and sometimes, and the lighting luminaries produced some annoying sounds. Studies assert that the presence of these problems in the working environment significantly reduces visual acuity, exerts difficulties in performing the tasks, and causes visual symptoms such as headache, eyestrain, teary eyes, and visual fatigue [
Improving occupants’ satisfaction requires an integrated lighting design method. A design which gives occupants the freedom to control some aspects of their offices’ lighting environment. User-centric lighting design is an ideal solution for improved occupants’ health and sustained good performance. This kind of lighting design was also reported in [
Besides, the existing literature affirms that occupants strongly prefer daylight to electric lighting [
Providing a healthy working environment is now a hot topic. Scores of the literature have reported that poor indoor environmental quality such as lighting has a detrimental effect on human health, and in case of the office working population, it affects their work performance as well. This study has examined the effects of lighting quality on working efficiency of workers in an office building in Tanzania. Some offices from the administration building at Mbeya University of Science and Technology were examined. The results have indicated that workers are less satisfied with their offices’ lighting environment. Physical measurements and researchers’ observations also depicted that the quality of the illumination was insufficient for a healthy working environment. Visual destructions such as glare discomfort, lighting flicker, and annoying sounds from defected circuits were alarming, and in most of the cases affected the occupants’ concentration. Also, the occupationally induced health symptoms such as eyestrain, headache, teary eyes, back pain, shoulder pain, and neck pain were significantly reported.
Furthermore, the research identified that poor lighting design techniques, use of outdated lighting technology, not adhering to different task lighting requirements, absence of local lighting codes and governing regulations, poor use of the concept of room index ratio, and poor choice of lighting luminaries were the factors which contributed to inadequate lighting in the surveyed office building (Table
Summary of the identified spatial lighting problems and the recommended remedial.
Factors identified | Identified problem | Proposed solution |
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Illuminance level and spatial partitioning materials | Lighting on the work plane was below the recommended level | Lighting fixture should be mounted at the appropriate height to ensure proper distribution of illuminance |
Lamp spacing and mounting height against the room index ratio was inconsistent | Lamps and luminaires should be cleaned regularly | |
Uneven distribution of light on the working area and the surrounding was observed | Defected lamps should be replaced | |
Veiling reflection was identified | Room surfaces reflectance should be improved by painting the walls with light colors, e.g., Paint white | |
Light being wasted to the ceiling and other areas which are not the visual target | Ambient task lighting methodology should be adopted to localize and personalize lighting | |
Using lamps luminaries with the reduced light output | Provide lighting fixtures and lamps with more efficient light output, e.g., T5 or LED lighting technology | |
Poor choice of partitioning materials and partitioning style | Lamps should be mounted on the luminaries with excellent light outputs | |
Use transparent or translucent partitioning materials, e.g., glasses; also, the partitioning should be kept a minimum | ||
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Brightness and contrasts | Luminaries were dully covered with cobwebs and other black spots, and bared lamps or surface mounted lamps were common | Light controllers should be installed to direct light to the required task area |
Reflecting surfaces such as walls, ceiling, and floors were painted to colors with poor reflective index | Luminaries with more efficient light output should be used | |
Reflecting surfaces should be painted into more bright colors, e.g., white colors for more reflection of light | ||
Use lamps with good color rendering effect | ||
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Flicker and sound | Lighting in most of the office experienced intensified flicker and produced the annoying sound | Electrical circuits should be revisited, and all possible faults should be rectified |
Magnetic ballasts were widely used instead of using electronic ballasts | High-frequency control gears should be used, and all lamps near the end of their life should be replaced | |
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Public awareness | The general public is not well informed about the effects of inadequate lighting on working efficiency and human health | Government and other stakeholders should prepare the education programs to raise awareness |
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Policy problems | Absence of local building codes and guiding regulations | Formulate and enact the local lighting design and building construction codes and regulations to guide the construction industry in Tanzania |
This research was limited to analyzing the effects of lighting quality on working efficiency of workers in an office building in Tanzania. The factors contributing to the effects have been identified and analyzed through physical observation and questionnaire survey. Four office rooms with good representation were identified, and measurements and physical analysis were conducted. However, the separation between sunlight and artificial light was not clearly made during illuminance measurements. Thus, prediction of the illuminance contribution between the two cannot be made. Some offices received a considerable amount of sunlight; however, occupants still kept the artificial light on to compensate the insufficiency. Therefore, in future research, it is recommended that these two scenarios be done separately in order to make a comparison and establish which kind of light is inadequately provided. Furthermore, the illuminance level requirement differs from one person to another and from task to task. The results of this study could be influenced by the characteristics of the studied population sample. The workers in the surveyed building have a variety of works performed in their respective offices, and their lighting requirements are different. Thus, for future studies, we recommend that groups of similar lighting requirements should be studied separately.
Data will be made available from the primary author upon request.
The authors declare that there are no potential conflicts of interest concerning this research, authorship, and or publication of the article.
This research was supported by the Program for Innovation Team Building at Institutions of Higher Education in Chongqing China under grant number (CXTDX201601005) and the National Natural Science Foundation of China (grant number 51778081) for the research on VDT Lighting Environment in Design Office Based on the Adaptation of Human Constitution. We want to convey our sincere thanks to MUST community for their maximum cooperation that was extended to us during the entire period of research. We also thank the office of estate Manager of MUST for their support of providing drawings and assistance in reaching many places of their facility.