Effect of Perceived Muda on Perceived Job Productivity in Public Office Buildings in Nigeria

Aims: The lean thinking concept, especially the application of muda was claimed to apply to a vast range of operations in widely differing industries, with only “tweaking of details”. Thus, varying industries adopted the concept including the built environment from whence terms such as lean construction and lean design emerged. The substantial argument was that the concept had delivered large improvements where already applied, this paper therefore looked into the practicability significance were used in determining the effect of muda on job productivity. Results: Perceived muda was established as inherent in the case study and ranked based on their respective unique contribution which ranged from 0.848 to 0.472. Muda has a causal effect of 0.646 on job productivity and a strong effect size of 42%. All the results were significant with P-values of <.05. Conclusion: Perceived muda has strong influence on perceived job productivity, especially by affording end-users to contribute to their requirements in office buildings, while it explained 42% of its variance; which is a strong effect size. This had confirmed that lean thinking is applicable to public office buildings in Nigeria and therefore relevant to their sustainable improvement.


INTRODUCTION
In its bid for Sustainable Development (SD), the UN Earth Summit of 1992 in Rio de Janeiro, Brazil called on member States to adopt and integrate the principles of SD into their national policies and programmes which would build upon and harmonize the various sectoral economic, social and environmental policies and plans operating in their respective countries [1]. However, over 20 years later (termed Rio + 20) many countries, especially in the developing world were yet to make significant headway in their quest for SD of their built environment [2,3].
A major cause attributed to this was the neglect of existing buildings which form the bulk of built assets in our cities [4]; they were developed decades ago when sustainability was not a consideration [5]. According to Wood [6], sustainability cannot be achieved without addressing existing building stock as it is unlikely that new build alone would deliver a sustainable built environment in the near future. Mickaityte et al. [7] noted that current improvement of existing buildings excluded major inputs from end-users, thus sustainable improvement is a significant problem in current building stock. Public office buildings in Nigeria was chosen, because they are constant subjects of discussion by eminent Nigerians and scholars alike in the country, while they also form the bulk of Nigerian property news in publications and on the internet. This paper thus look at the sustainable improvement of existing public office buildings, especially the impact of muda (from users' viewpoint) on perceived job productivity, which [8] described as the quintessence of an office building. Brandon & Lombardi [4] estimated that 87% of existing building stock will still be standing by 2050 which therefore goes without saying that existing building stock requires effective sustainable improvement that will sufficiently reflect users' requirements, especially in developing countries like Nigeria with an estimated population of over 170 million people [9], the 6 th most populous country in the world, the most populous and largest economy in Africa [10].

Waste and Inefficiencies (Muda)
The basic function of a building (including offices) is to provide structurally sound and environmentally controlled spaces to house and protect occupants and contents, but this basic function is not achieved if some aspects of the building fail and the needs of the occupants are not met according to the definition of SD. Failures of basic building functions can range from defects in single components such as windows to extensive deficiencies in an entire exterior wall system. The source of these deficiencies can include inadequate design, improper execution of the work, defective materials, or simply normal and expected aging perhaps coupled with lack of maintenance [11].
Womack & Jones [12] likened these failures to waste and inefficiency, which they defined as any facility, which absorbs resources but does not create the required value. The AED [13] also defined waste as any material unused and rejected as worthless or unwanted, while inefficient was defined as not producing desired results, or lacking ability to perform effectively. An example of waste in a building is when utility costs incurred on a building could be reduced with proper design, which allows for day lighting to replace electrical lighting.
'Inefficiencies' in office buildings can also be seen as when a building or its components not having the ability to function effectively. An example given by Adeyemi et al. [1] is a building having two-ply sliding window in a humid and hot environment without provision for artificial ventilation; in such situation, the window can only provide a maximum 50% opening as compared to louvres that can provide up to 95% opening. Thus the former has more of aesthetic value than functional value; the sliding window may therefore be regarded as inefficient because it does not have the 'ability' to provide enough ventilation in a hot and humid environment without further provision for artificial ventilation, whereas it can be more efficient in temperate regions or in built assets with further provision for artificial ventilation such as air conditioners. This problem is more pronounced in developing countries where electricity supply is very erratic and thus, even the provision of artificial ventilation may still not solve the problem of the 'inefficient' windows [1].
According to Spring [14], architects are often criticized for giving preference to aesthetics rather than functionality and in so doing are mainly responsible for most muda inherent in building designs. Improper use of day lighting due to wrong design or placement of window(s) can reduce productivity in offices and increase employee absenteeism due to the possibility of extremely high lighting levels, excessive glare, and high temperatures [8,11]. This paper appreciates that waste is extensively used in a different perspective in environmental management, especially for garbage, refuse, scraps, etc.; these could be termed tangible waste. However, in recent times emphasis is also given to intangible waste, and promoted by models such as Lean Thinking, Zero Emissions and Green Building. In this paper therefore, the intangible waste was emphasized above tangible waste and it is considered as anything that does not provide the required value to the ultimate user [12]. In order not to confuse the two, waste and inefficiencies in this study were henceforth referred to as 'muda' (Japanese word for intangible waste and inefficiency, promoted by [15].

The Concept of Muda in Lean Thinking
Lean thinking has the underlying philosophy that by identifying and eliminating muda, standard (hence performance) can be improved to meet users' requirement [16]. The concept of muda (seen as the opposite of value) became one of the most important concepts in quality improvement activities primarily originated by Taiichi Ohno's famous production philosophy from Toyota in the early 1950s. He realized on his visit to Ford Motors, in USA that there was too much muda in the production line, which he classified into 7, namely: defect/error, inventory, waiting/delay, motion, transportation, overprocessing and overproduction [15]; this Toyota production system is what is branded as lean thinking by [17]. Womack & Jones [12] later added the 8 th driver -human talent.
According to Nicholas & Soni [18], the two overarching philosophy of lean thinking for sustainability are elimination of muda and continuous improvement (or kaizen in Japanese). Wang [19] explained that kaizen is a system of continuous improvement in quality, technology, and safety, while Jylhä & Junnila [20] defined it as the effort for perfection which is never reached, but creates the urge to make improvements, as there is no end to muda elimination. Kaizen works by utilizing everyone's knowledge to identify and implement improvements quickly [21].
The concept can be applied to varied operation and processes in widely differing industries, offices, health care, etc. with only "tweaking of details" [18]. Thus, varying industries have since adopted the concept, including the construction industry from whence terms such as lean construction and lean design emerged. The substantial argument was the claim that the approach had delivered large improvements in manufacturing, in particular the motor vehicle industry, and where already applied in construction.
Schipper & Swets [22] also opined that muda is universal, appearing in every situation and they remain constant, but the definitions of the terms will change and adapt to describe the situation to which it is applied. Likewise, Finch [23] argued that the tools and principles of lean thinking cannot simply be exported from one environment to another without carefully analyzing the nature of the new environment. Thus, the muda drivers adopted for in this paper were modified to suit the concept and objectives of the study as depicted in Table 1. Devellis [24] claimed that theory plays a vital role in the conceptualization of measurement variables. Situation where one or more elements of a building do not perform their intended function [26]; and failure in the function, performance, statutory or user requirements of a building that manifests itself within the structure, fabric services or other facilities of the building [27]. 2 Inventory Storage facilities; and building materials kept for maintenance that are not necessary or have short life spans. 3 Waiting Delay, due to inadequate provisions for access to carry out maintenance activities, etc. 4 Motion Wasted human motion is related to workplace: ergonomic design negatively affecting productivity, quality & safety e.g. walking, reaching and twisting [28]. 5 Transportation Distant location of complimentary offices and other ancillary rooms causing unnecessary movements for users. 6 Overprocessing Adding Design Features not needed by users, e.g. bath tubs in general convenience; irregular office shapes that reduces functionality; etc. 7 Overproduction Large spaces, too many corridors, etc. which are not appreciated by users. 8 Human talent Non-inclusion of end-users' input (or talent) in design, maintenance or improvement policies. How could people be better involved in continuous improvement?

Job Productivity
Gou [29] reported that office workers nowadays spend almost 90% of their time indoors, implying that IEQ conditions (i.e. air quality, temperature, lighting and noise) would consequently have farreaching implications on their health and job productivity. A leading argument for economic sustainability is the belief that sustainable office buildings are healthier and lead to job satisfaction, less employee absenteeism and higher levels of job productivity thereby boosting overall profitability of office occupiers [30,31]. Satisfaction with the physical working environment was also reported as directly related to job satisfaction and productivity [32].
Haynes [8] observed that the quintessence of an office is job productivity and thus developed a validated theoretical framework for the measurement of perceived job productivity based on 2 data sets of physical environment and behavioural environments (Fig. 1). In the framework, 4 components were identified, namely: comfort, office layout, interaction and distraction (Table 2); the framework is related to the superstructure of built office environment, in line with the scope of this study and was thus adopted.

User Requirement and Self-assessed Job Productivity
According to Jylhä & Junnila [34], facility management literature in recent years had discussed the shift from bricks and mortar to an end-user-driven mindset; the focus is no longer only on cost minimization and real estate operations but rather on supporting end-users, while [35] opined that knowledge of the expectations of end-users is required in order to make proper decisions connected with the improvement of office buildings. Studies have shown that users' requirements were not well captured in purported sustainably improved buildings [36,37]. Jylhä & Junnila [20] thus rightly opined that the ultimate goal is to produce and deliver occupants' requirements and only the occupants themselves can define it.
Love & Bullen [38] opined that current assessment systems of performance of existing buildings pose challenging problems because they do not provide a full profile of sustainability since they excluded major inputs from end-users.
Hebert & Chaney [39] also observed that very few published studies have reported the use of end-user surveys during the design process to inform the improvement of a facility.
Karna [40] defined users' satisfaction as when the quality of a service meets or exceed their expectations; thus they are not satisfied otherwise. From this perception, an important attribute of user satisfaction that could serve as a measure of performance is the reference to the user as a key determinant of quality [41]. Therefore, every quality improvement needs to be directed towards ensuring that products fulfill the requirements and specifications assigned from users' standpoint [42].
Thus, the most important factor as a benchmark for a building improvement to meet sustainability objectives is the level of users' requirements and satisfaction incorporated in it [43]. Black [44] observed that world class services/products incorporate intense end-user focus in which the end-user is an indispensable part of the process. He gave the example of Boeing (aircraft manufacturer) who involves users' views in its production process in what is termed aggressive listening; the building industry also needs to focus on end-users' satisfaction in order to generate world class facilities.
Veitch [45] also argued that the relationship between users and the office building cannot be reduced to functionality, as users do not assess their requirement on the basis of simple physical comfort, but bring their feelings, memories, expectations, and preferences into their assessment, which increases the complexity of the outcomes being measured. This had therefore led to the acceptance of self-assessed performance [37,29,46], and thus adopted for this paper. Haynes [8] argued that since there was no universally accepted means of measuring job productivity, there appears to be acceptance that a self-assessed measure of productivity is better than no measure of productivity, while Oseland & Bartlett [47] also opined that selfassessment of productivity was not a new measure, and went on to argue that perceived productivity could be as important as actual productivity. The relationship between user requirement and job productivity from literature is illustrated in Fig. 2.

METHODOLOGY
The confirmatory study adopted the quantitative method, supported by qualitative method, while the research strategy involved the use of survey, direct observation and case study approach. Qualitative method involved the review of relevant literature from which questionnaires were designed and administered to the occupants of case study building. Quantitative method involved the use of SPSS, AMOS (being a confirmatory analysis tool), while the causal effect, effect size and practical significance were used in determining the effect of perceived muda on perceived job productivity [48]. A preliminary

Fig. 2. Office environment and job productivity relationship impression
Confirmatory Factor Analysis (CFA) was conducted to ensure that there was no violation of the assumptions of unidimensionality, validity, reliability and normality, such that any item that does not fit the measurement model was removed.
The diagnostic POE tool was adopted for this study, while its working depth was limited to the systematic evaluation of opinion to establish perceived muda and its effect on perceived job productivity from occupants' perspective through questionnaires, in order to assess how well the building match their satisfaction, expectancies and needs, and identifies ways to sustainably improve the building standard, performance and fitness for purpose [49]. Acquired data relates to the SD triple bottom line (TBL) components of environmental, economic and social dimensions [50], but limited to: (a) The 'environment' covering issues, which include temperature, ventilation, air quality, glare, daylight and noise [42]; (b) The 'economy' covered issues of occupants' satisfaction and comfort through the provision of adequate space, services and facilities thereby increasing job productivity. Satisfaction with the physical working environment seems to be directly related to job productivity [32].
(c) The 'social' covered the issue of aesthetics; where buildings having pleasing aesthetic qualities with prompt repair and regular upkeep, enhancing their surroundings and the well-being of humans [51].
Preliminary analyses were performed on all the measurement models using the The Federal Secretariat complex, Bauchi (Fig. 3); a massive public building in Nigeria was chosen as case study because of more dire need for improvement in developing nations [52,53,3]. Eisenhardt [54] suggested that a single case study method tends to be more appropriate to confirm or challenge a theory or address a rare or unusual situation. iii. The building is still operational and not abandoned; iv.
A massive structure with 26 government offices with a combined staff strength of 971; and v.
The staff combination reflects the federal character and quota system of the nation.
According to McIntyre [55], a representative sample is crucial if evidence from the sample is being used to make generalizations about the larger population from which the sample was selected. However, all the occupants of the Federal Secretariat building, Bauchi, Nigeria were adopted as the research sample size, to reflect the federal character and quota system of the nation [56]. The questionnaire was distributed to the 971 staff at the case study, thus no sampling technique was employed. However, a sample size calculator was used to estimate the minimum sample size of 280 required for the study [57]. The retrieved and useable questionnaires was 339.
The variance in perceived job productivity was diagnosed from an integrated perspective [31], first using simple frequency distribution of the processed data from user standpoint based on the physical and behavioural environments data sets [33] after which AMOS regression analyses were conducted to determine whether the subconstructs loads well and to evaluate the causal effect. Fig. 4 depicts the regression weights of the muda drivers predicting perceived muda, while Table 3 showed the summary of the good Fitness Indexes (FI).

Establishment of Perceived Muda and Ranking
The study confirmed that muda is inherent in the subject building thus confirming [18,22,23] who argued that muda is universal, appearing in every situation and they remain constant. Figure  4 and Table 5 showed the unique contributions of the drivers with their respective beta coefficients. According to Pallant [58], the driver with the largest beta coefficients makes the strongest contribution; the drivers were thus ranked based on their respective beta coefficients, which indicate the unique contribution of each subconstruct to explaining perceived muda.
The corresponding effect size of R 2 of the drivers are all strong, save Waiting (WAT) with a moderate range of 0.22. Table 4 shows the interpretation of effect sizes by Adams & Lawrence [48] and Awang [59], while Table 5 shows the regression weights of the muda drivers have significant coefficients.

Variance in Perceived Job Productivity from Users' Perspective
From the frequency distribution of the data acquired during survey (depicted in Table 6), users' perception of the variance of job productivity within the office complex revealed that apart office layout, all other components have negative impacts on perceived job productivity.  and Distraction (DST) is 0.71 (Fig. 5), they are all above the threshold of 0.6 and thus confirm that perceived job productivity consists of the 4 Table 6. Respondents' perception of S/No Job productivity sub-constructs Comfort component (CFT) 1 Level of illumination (DAYL) 2

Interaction component (INT) 9
Social interaction SINT) 10 Work interaction (WINT) 11 Aesthetic qualities (AEST) 12 Refreshment areas (RFSH) Distraction component (DST) 13 Noise and disturbance (NOIS) 14 Toilets' sanitation level (TOIS) 15 Frequency of downtime (DNTM) 16 Electricity supply (ELEC)  and Distraction (DST) is 0.71 (Fig. 5), they are all above the threshold of 0.6 and thus confirm that perceived job productivity consists of the 4 components and can thus be used for fu analysis [60]. The required level is achieved The required level is achieved The required level is achieved The required level is achieved Table 8 shows the path analysis of perceived job productivity on its sub-constructs, together with their respective level of significance and beta estimate. Fig. 6 is the proposed structural model with good FI (Table 9), and it depicts the causal effect of perceived muda on perceived job productivity (Table 10), with a highly significant coefficient. The standardized beta estimate of 0.646 reflects the amount of causal effect of perceived muda on perceived job productivity, thus when muda goes up by 1 unit job productivity will also go up by 0.646 unit. Furthermore, the R 2 of 0.42 (Fig. 6) indicated a strong effect size of muda on job productivity, implying that inherent perceived muda explains 42% of the variance of perceived job productivity within the office complex.

CONCLUSION
This paper concludes that muda is universal and inherent in public offices in Nigeria as claimed by Nicholas & Soni [18], Schipper & Swets [22] and Finch [23], and that it has strong influence on perceived job productivity, which is the quintessence of an office building, especially by affording end-users to contribute to their requirements in office buildings [7]. The muda drivers are ranked in the order -Inventory, Defect, Over-processing, Overproduction, Motion, Transportation, Human Talent and Waiting, based on their unique contributions and effect sizes.
Perceived muda explained 42% of the variance in perceived job productivity, which is a strong effect size. All the result have practical significance with P-value of <0.05. This had confirmed that lean thinking is applicable to public office buildings in Nigeria and therefore relevant to their sustainable improvement. Although, there are a number of other factors and barriers that affect the ability to sustainably improve existing building stock, however, until the major issue of muda is addressed from endusers' perspective, the pace of SD may remain slow, especially in developing countries.