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Potential of lean construction concepts in promoting ‘Green’er constructionANN FRANCIS – Planning Engineer, L&T
Contents 1. Abstract ........................................................................................................
1. AbstractThe recent increase in the awareness of carbon emissions, global warming and environmentalfootprint is exerting...
3. Lean ConstructionTraditional construction practices focused mainly on three major parameters cost, quality and timewhil...
Pull Mechanism: - The principle highlights on the necessity to produce only what is wanted,    when it is wanted. This con...
Most of the wasteful practices can be reduced by changing managerial practices while design,procurement and production sta...
Wang and Guiyou (2011) highlighted that in the aspect of cost management, the nature of the „Lean‟construction is to elimi...
For each activity, a current state map was drawn which showed the cycle time, inventory and alsodepicted the wastes in the...
Figure 2:- Future state map of open foundation activity at Site 4After the current state map is derived, the carbon footpr...
alignment problems. Also the ground over which pile rig was placed was not leveled leading tostability issues. Another maj...
8. Finishing activities Block work: - The current state map of the block work activity at site 2 showed that, the major „l...
concrete delivery on site showed larger footprints owing to the large amount of transportation ofmillers. It is difficult ...
8. Jensen, W. &Kouba, A. (2007),“The role of the contractor in sustainable construction”.The   American Professional Const...
25. Wang Guangbin, Guiyou and Bian Li (2011), “Sustainable Construction Project under Lean    Construction    Theory”,    ...
11. Author’s Profile                   I am a civil engineer by profession. I have completed my B-                   Tech ...
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  1. 1. 1 Page
  2. 2. Potential of lean construction concepts in promoting ‘Green’er constructionANN FRANCIS – Planning Engineer, L&T
  3. 3. Contents 1. Abstract ........................................................................................................................................... 4 2. Introduction...................................................................................................................................... 4 3. Lean Construction ........................................................................................................................... 5 4. „Lean‟ and „Green‟ relationship ........................................................................................................ 7 5. Research Methodology ................................................................................................................... 8 6. Foundation activity ........................................................................................................................ 10 7. Structural Concreting activities ...................................................................................................... 11 8. Finishing activities ......................................................................................................................... 12 9. Conclusion..................................................................................................................................... 12 10. References .................................................................................................................................. 13 11. Author‟s Profile ............................................................................................................................ 163 Page
  4. 4. 1. AbstractThe recent increase in the awareness of carbon emissions, global warming and environmentalfootprint is exerting pressure on the construction industry to emphasize on the environmental impactof the industry. A paradigm shift from the conventional objectives of cost, quality and time to abroader view in terms of environmental sustainability is the need of the hour. This demands theintroduction of construction management strategies that can control and reduce environmentalimpact, and at the same time those which ensure profit and customer satisfaction. „Lean‟ constructionis such a production based strategy that focuses on reducing all types of resource wastage and alsoensures reliability in the work flow of the construction processes.This paper investigates the impact on environmental footprint due to the implementation of the „lean‟principles to improve various construction processes like open foundation, piling, concreting works,block work and structural steel work, observed at different sites in India. Value stream mapping toolwas used to diagnose the wastes defined by „lean‟ literature, for the various activities. The studyshowed that if these wastes were targeted under the „lean‟ perspective then the carbon emissionscould be reduced to a considerable extent. By implementing „lean‟ concepts in the process, for aPiling and Open foundation activity a reduction of 16% and 26% of carbon emissions was possible.Similar was the case with concreting activity (13%) and block work activity (18%). The paper thusemphasizes on the need of better construction practices like „lean‟ to make construction „green‟.2. IntroductionConstruction industry is making significant contribution to the economic development but, the processof construction and building operation is directly or indirectly leading to depletion of natural resources,increased emissions, high energy consumption, degradation of the ecosystem and unpredictableclimate change.( Kibert, 1998, Hendrickson & Horvath, 2000; Horvath, 2004). For example, buildingconstruction and operation accounts for 40% of the materials and 33% of the energy used in theworld economy (Rees, 1999). The construction industry should take considerable effort in reducingthe impact on environment by improving the environmental performances of the buildings andinfrastructure.Major focus of studies in the area of environmental sustainability of buildings has been concentratedaround the building‟s operation phase (USGBC, 2005; Kibert, 2007; Jensen & Kouba, 2007); whilethe other phases are given inferior attention. Even the „Green‟ rating systems like LEED (Leadershipin Energy and Environmental Design), and GRIHA (Green Rating for Integrated Habitat Assessment)the on-site factors like carbon emissions from equipments, transport etc. are not given criticalattention. It is essential that, for a project to be called „environmentally sustainable‟ efforts should betaken to enhance its environmental performance while designing, during construction, operation andfinally when demolition or rehabilitation becomes necessary.Numerous studies have been conducted to develop process and technology innovations andalternative low carbon materials, to achieve better environmental performances. However, it shouldbe noted that the non-technical issues should not be overlooked when reducing carbon emissions, i.e.the improvement at the managerial level (Wu Peng and Low Sui Pheng, 2011). Hence focus shouldshift to adapt strategies which can balance both the technical and non-technical improvementsrequired in the construction process. „Lean‟ production system could be a probable strategy in thisbackground, as it talks in terms of waste minimization and improving work flow reliability. Thisresearch is therefore aimed to highlight the relevance of „lean‟ culture in construction and understandhow it can yield „green‟ benefits. It should be noted that „Green‟ in this paper refers primarily toreduction in the carbon emissions due to on-site operations like from improper use of equipments.4 Page
  5. 5. 3. Lean ConstructionTraditional construction practices focused mainly on three major parameters cost, quality and timewhile modern design and construction additionally concentrates on minimization of resourcedepletion, minimization of environmental degradation, and creating a healthy built environment (Kibert1994). A paradigm shift of this nature calls for a change in the prevailing culture of the constructionindustry so as to promote infrastructure that is reliable, sustainable, and economical and serves itsultimate purpose.„Lean‟ construction‟ presents itself as a revolutionary philosophy, extracted from the manufacturingindustry, which underwent huge reforms on introduction of Toyota‟s „Lean‟ production managementsystems. „Lean‟ philosophy brought out the concept of conversion activities (value-adding) and flowactivities (non-value adding). While traditional management improvement did not give due concern tonon-value adding activities, „lean‟ strategy treated conversion and flow activities separately.Conversion activities are to be improved while flow activities are to be eliminated.The Toyota Production system is the birthplace of „Lean‟. Engineer Taiichi Ohno was the architect informulating the „Lean‟ philosophy which focused on minimization of all types of wastes. Lauri Koskelaproposed the Transformation-flow-value understanding of construction (Koskela, 1999) in thebackground of the established manufacturing theories of „lean‟. He explained the framework in which„lean‟ production system could be applied to construction. The goal was to take the basic „lean‟motives such as elimination of waste, cycle time reduction, variability reduction; pull driven productioncontrol, continuous flow and continuous improvement, as foundation stones and developingmethodologies and applications in the context of construction.The „Lean‟ Project Delivery System (LPDS) is a product of the „lean‟ construction institute founded byHowell and Ballard to develop a leaner way to design and build capital facilities (Ballard 2000). The„Lean‟ Construction Institute (2004) defines the term „Lean‟ construction as: „Lean‟ Construction is aproduction management-based approach to project delivery -- a new way to design and build capitalfacilities.The simple ideology of „Lean‟ construction is to give customers what they want and at the specifiedtime and with minimum wastage of resources. „Lean‟ is not a methodology or tool that can be used forimproving performance; it is a philosophy to be inculcated into a process to promote reliability downthe line to the final construction product. It ultimately promotes speedy and reliable construction withreduced wastes along with overall profit and competiveness. Where current project managementviews a project as the combination of activities, lean thinking views the entire project in productionsystem terms, that is, as if the project were one large operation. To understand the potential „lean‟thinking in addressing environmental problems it is essential to understand the core principles of„lean‟ in which are briefly described in the context of construction as follows. Value: - The first step in „Lean‟ implementation is to understand how „value‟ is perceived from the customer‟s view point. In construction it means identifying the tasks which add „value‟ to the final constructed facility. Everything that does not add „value‟ is to be considered a waste. For e.g.:- Idle labour, machines, rework, waiting for instructions etc. Thus it is essential to derive a „value stream‟ for the entire construction process which involves identifying and integrating the processes that deliver „value‟. The focus should be on identifying the proper „value stream‟ and targeting the non-value adding tasks so that cycle times can be reduced and efficiency can be improved. Flow: - One of the prime objectives of „Lean‟ is to make „value‟ flow, by eliminating the obstacles which hinder the smooth conduct of the tasks. Koskela (2000) states that “Creating continuous flow in construction is a huge challenge due to its fragmented nature, low standardization patterns of activities and uniqueness of construction projects”.5 Page
  6. 6. Pull Mechanism: - The principle highlights on the necessity to produce only what is wanted, when it is wanted. This contradicts the conventional approach maximizing individual productivities to achieve results. The downstream demand should trigger the upstream working as per „Lean‟ theory. Perfection:- Quality improvement programs have progressively become integral aspects of the construction industry. Results of this strategy are that reasonable improvements and standardization of tasks have been achieved (Flavio and Granja, 1999). „Lean‟ thinking focuses on pursuing perfection through a continuous improvement process thus restructuring the process continuously so as to improve performance.Suitable changes and modifications have to be made in the „Lean‟ theory principles developed byToyota to allow its better application in construction scenario because of the uniqueness of theindustry‟s products. Implementation of „Lean‟ is a simple two-step process namely: - Finding wasteand eliminating it. SECBE (2008) estimated that 30-40% of construction activity did not add „value‟ forthe customer. Examples include waiting for information and materials, reworking due to defects,double handling of materials, unnecessary movements around site due to poor site layout and accessarrangements etc. There is evidence in the literature and industry practice that waste reduction isachieved through „Lean‟ implementations, in particular material waste (Womack and Jones 1996;Salem and Zimmer 2005; Nahmens 2007; Nahmens and Mullens 2009).Taicchi Ohno (1998) categorized the non-value adding activities or „waste‟ in production systems intoseven categories as listed below. These categories are suitably defined in the context of constructionas follows. The possible environmental impacts of these wastes are also briefed. Waiting Waste: -It results from periods of inactivity due to incomplete or delayed preceding activities. For e.g.:-Mobilization delays, equipment waiting etc. resulting in increased cycle times, energy wastage due to unnecessary working of machine/equipment , spoilage or damage of materials (Concrete, pile bore etc.). Motion waste: -When there is problem in the process layout, defects and excess inventory etc., extra steps have to be taken to mitigate these inefficiencies which are termed as motion waste. This leads to doing tasks which add no „value‟ but increase the duration and Increased energy consumption and emissions. It might also lead to damage and spill due to excess movement Over-processing waste: - This refers to unnecessary tasks carried out in the construction process with a view of adding „value‟ to the process but actually leads to excess costs and increase in cycle time. It includes double-checking, double handling, reprocessing etc. More materials consumed than necessary and also leads to excess energy consumption, emissions and material wastage Over Production waste: - Such waste occurs because of producing more than what is needed, faster than needed or before it is needed when ideally the tasks should have stopped. This leads to incurring excess costs, excess inventory, storage and maintenance problems. It leads to wastage of materials and energy in making unnecessary products. Transportation wastes: - As termed it means, wastes due to excess transportation of man, material or machines due to improper planning of job or poor logistics at the site. It should be given due attention because it leads to increased cycle time with no „value‟ adding activity being performed; excess costs are incurred and materials are exposed to handling damages. It also contributes to excess energy consumption and emissions. Inventory waste: - Waste of storage space, material damage and accumulated monetary loss occurring due to stocking of materials or equipment in excess than required or when there is low a demand/usage. Inventory demands extra energy consumed in creating suitable storage conditions and space for different materials. Defects/Rework waste: - Waste of time and material occurring due to flaws in the construction which needs to be rectified. It occurs mainly with design changes, poorly skilled labour, work not conforming the quality standards or specifications etc. Rework leads to further consumption of energy and materials and unwanted emissions.6 Page
  7. 7. Most of the wasteful practices can be reduced by changing managerial practices while design,procurement and production stages. Most of the wastes can be eliminated with proper planning andcontrol of the construction activities.Though „lean‟ philosophy leads to the improvement of the efficiency and reliability of construction, it isimportant that it does not impact the environment negatively. „Lean‟ considers the aspect of wastereduction which also is a goal of „green‟ construction but, it is necessary to investigate if it burdens theenvironment by any other aspect. This study thus focuses on analyzing possible linkages between„lean‟ and „green‟ philosophies and to establish if by being „lean‟ can we be „green‟ too.4. ‘Lean’ and ‘Green’ relationshipGreen Building, also known as Sustainable Building, is the practice of creating structures and usingprocesses that are environmentally responsible and resource-efficient (U.S Environmental Protectionagency). As per emission statistics in UK and USA about 80-90% carbon emissions is said to be fromthe building operation phase while remaining is contributed by the raw material, on-site construction,and demolition or recycling phases of the building‟s life cycle. Some existing research have thusassumed that the impacts of the „construction phase‟ on the environment are negligible (Horvath et al.2003), while others have indicated that the environmental impacts associated with on-siteconstruction processes are underestimated (Hendrickson2000). This is due to the lack of well-defined„green‟ construction practices and lack of metrics to collect accurate construction data and measureenvironmental sustainability. Process-specific quantification of resource and environmental impacts ofon-site construction processes is essential to understand and improve the environmental performancein the construction phase.Since „Lean‟ is a philosophy originated from manufacturing environment, it is essential to track downthe relationship of „Lean‟ and the environment from the production platform itself. In the manufacturingcontext, it was found that by adopting the aspects of „Lean‟ production philosophy and that ofenvironmental management systems they could achieve reduced pollution and increased efficiency(King 2001, Hart et al., 1999, Gandhi et al., 2006). The EPA (2003) proposes that „Lean‟ provides aplatform that is highly focused on waste minimization and pollution prevention in an operationalenvironment, and hence provides an excellent foundation for environmental management tools suchas life cycle assessment and design for environment.Riley et al. (2004) stated that, the greatest barrier to the construction of „Green‟ buildings in a largescale was the higher initial costs, which were largely due to the learning curve of workers in buildingwith complex technologies and using unfamiliar materials, large design iterations, plus the added costresulting from immature construction processes. Isabelina and Laura (2011) suggest that theintroduction of „Lean‟ construction could solve these problems as; it provides a more structured job-plan into which the „Green‟ objectives can be easily incorporated. Nahmens (2009) stated that it wasa natural extension to apply the „lean‟ concept to achieve „green‟ production and construction.Wu Peng and Pheng, (2011) studied whether „lean‟ production philosophy is applicable in precastconcrete factories to achieve sustainability They found that for a precast concrete columnconstruction, an amount of 8.3% carbon emissions was reduced when the „lean‟ productionphilosophy was adopted in the casting yard. They suggested that the evaluation of the „lean‟ conceptin achieving environmental sustainability could only be examined when environmental sustainabilitywas set at the target at the very start. The contribution of the „lean‟ concept to „green‟ could not befully assessed when reducing initial costs and eliminating waste were set at the targets.Koskela,(1998) suggested that the principles of „lean‟ construction should converge to thesustainability objectives in the form that „Eliminating „waste‟‟ should mean minimization of resourcedepletion, minimization of pollution and, adding „Value to the Customer‟ should mean business andenvironmental excellence.7 Page
  8. 8. Wang and Guiyou (2011) highlighted that in the aspect of cost management, the nature of the „Lean‟construction is to eliminate waste, which will change or eliminate the invalid time and outputs and thusdeliver projects without increasing cost. They concluded that the theory of „Lean‟ construction wasalready offering the conceptual basis, and potential for novel methods and tools for sustainableconstruction.Though literature shows that „lean‟ has the potential to incorporate „green‟ objectives into its strategicplan, it does not show precise and direct linkages between the two concepts. Researchers also arguethat „lean‟ might demand excess and sophisticated technology which might not cater to the „green‟objectives. A study is thus necessary establish a direct linkage between the wastes defined by the„lean‟ theory and the quantum of impact their reduction/elimination has on the emissions.5. Research MethodologyThe methodology followed for the research is summarized as follows Different construction activities at sites and at different stages of construction were identified. „Lean‟ value stream map was used as the tool to diagnose the wastes in construction activities Current state maps of different activties were drawn. Equipment emission data was collected and material wastage if any was noted.The energy consumed in the process was converted to carbon dioxide equivalent values. In each process the sub-activites were categorised to value adding and non-value adding.The non-value adding activities were targetted and eliminated/reduced A future State Map was proposed for the activities by trying to eliminate all the possible wastes in the process as defined by „lean philosophy and the results were validated Carbon emissions were recalculated based on the new future state map to identify considerable changes, if any, due to reduction in cycle time in the future state map.For the purpose of this study four construction sites were selected from which six individual activitieswere chosen to obtain qualitative and quantitative data (Table 1). Qualitative data was obtainedthrough activity observation and semi-structured interviews with the engineers. Quantitative datarelated to energy use of equipments was obtained from P&M department. The activities were chosenin such a manner that they would act as a representative of an entire construction project i.e. frominitial piling or foundation stage through structural concreting works and some finishing works. Theauthor intends to present these activities not from an individual perspective but as though itrepresents all the major stages of a project i.e. foundation, structure and finishing works. Table 1:-Activities studied TYPE ACTIVITIES CHOSEN FOR STUDY SITE 1 IT Building Piling activities. SITE 2 IT Building Concreting activity and Block work activity SITE 3 Residential Concreting activity SITE 4 Metro rail station Open foundation and Concreting activityStudies suggest that VSM is one of the best visual tools that clearly depict information and materialflow in a process. It has generally been used to assess the cycle time, lead time, and inventory levelsetc. to define value and waste, since these are the key focus areas of „lean‟. VSM increases thetransparency and predictability of construction processes and hence helps people to have a thoroughunderstanding of processes. This tool can be made more useful by adding environmental impact datato it. Symbols can be used to denote the emissions and other environmental hazards.8 Page
  9. 9. For each activity, a current state map was drawn which showed the cycle time, inventory and alsodepicted the wastes in the process. The aim was to attack these problems found in the process andto reduce/mitigate them. Symbols are used to denote the processes, flow, inventory etc. A timeline isshown below which indicated the time flow at each point of the process. The current state map of anopen foundation activity at Site 4 is shown in Figure 1. along with the proposed improvements.Figure 1: Current state map and proposed improvements of an Open foundation activity at Site 4A future state map is now drawn incorporating all the measures taken to improve the process. Thefuture state maps represent a better way in which the work could be done and in lesser time. Theproposed future state maps should be validated preferably by actual on-site implementation or byusing simulation software‟s. Figure 2 shows the future state map of the open foundation activity.9 Page
  10. 10. Figure 2:- Future state map of open foundation activity at Site 4After the current state map is derived, the carbon footprint calculation of the process in theperspective of equipment emissions is done. Measurement of carbon emissions is one way tounderstand and improve the environmental performance of onsite construction processes. Theenergy consumption of all the equipments used in a particular process is considered for carbonemission calculation. The energy consumed in liters of fuel or kilo watt hour of electricity is thenconverted in terms of Kilograms of CO2 to get the emissions. The conversion values used in thisstudy is based on the National Atmospheric Emissions Inventory UK (2003).Recalculation of this footprint is done as per the proposed future state map. The difference shows thepercentage reduction in emissions by following a better and reliable process after eliminating all the„lean‟ wastes identified. Due to the limitation in the time frame of the study, in this study onlyconstruction equipment emissions are considered for carbon footprint calculation. Material embodiedenergy or energy consumption of small electrical appliances like bulbs etc. are not considered. Theenergy consumption of the equipments are calculated and converted to kg CO2 equivalent using theconversion factors. Only countries like US and UK have specific conversion factors to find out theKgCO2 value, but they are considered as standard values because they represent the values basedon burning of one unit of the fuel. The activities considered are briefed as follows. Current and futuremaps for all the activities could not be shown in the paper due to limitation in space and hencereaders are requested to follow the representative example in figures 1 and 2.6. Foundation activityPiling Activity:- The installation or construction of pile foundations is generally associated withnumerous problems. The current state map of the piling activity observed showed that mobilizationdelays and poor site logistics were the main issues. Initial errors in surveying caused delays and10 Page
  11. 11. alignment problems. Also the ground over which pile rig was placed was not leveled leading tostability issues. Another major delay was due to the improper planning for the bentonite flow, whichrequires bunds to be made so that the bentonite can overflow away back to the tank. The poorlogistics also effected the transport time of concrete and steel to the pile location. Concrete supplywas interrupted frequently owing to the frequent technical problems in the concrete batching plantleading to stoppage of work. This delay caused further difficulties in the removing the casing from thepile. Most of these problems could be addressed by proper planning and control of the activity.The main objective of the current state map is to understand the problems or „wastes‟ in a process.The seven wastes defined by „lean‟ literature were looked upon. The various sub-activities observedwere categorized into value-adding and non-value adding as per the „lean‟ principles. The non- valueadding activities were further divided to two categories:- Type 1 and Type 2 muda. Type 1 mudameans those which are necessary for the process but do not add any direct value to the finalproduct/output. They cannot be eliminated but can be modified to reduce the cycle time. Type 2 canactually be eliminated or is not required in the process but is still performed. Most of the sub-activitiesfound as wastes were those which were required for the process but were not judiciously planned andexecuted. The study focused primarily on the wastes which caused unnecessary emissions, like delayin emptying of concrete trucks, idle operation of equipments, excess transport emissions due to poorlogistics, and delay due to poor planning. It should be noted that the equipments should work to addvalue to a process and working more than what is required leads to wasteful emissions.In the piling activity it was observed that by ensuring proper logistics at site and better site planningthe cycle time per pile could be reduced from 4.15 hours to 2.8 hours. This resulted in acorresponding reduction in the carbon footprint by16%. This was mainly due to improvement in termsof a properly prepared ground surface and better logistics for movement and better planning andmonitoring of works, which permitted smooth flow of work and lesser environmental impact.Open Foundations:- In Open foundation activity at Site 4 about five foundation works were observedand the major problem was the site traffic management because of the congested location. Gettingbetter productivity from the excavator was also a major challenge. Concrete trucks queued at the sitecreating further problems. Improper labor mobilization and poor quality were other pinching problemsfound in the site. Following Just-in-time concrete delivery and logistics plan approach in the „lean‟perspective could bring down the cycle time from 26 hours to 23 hours for each footing. This resultedin a reduction of carbon emissions by about 26%. Such constructions should give key attention toensure proper site planning prior to commencement of work (Refer Figure 1 and 2 for current stateand future state maps)7. Structural Concreting activitiesConcreting activities observed showed that the major problem is the interruption of concrete supply orexcess waiting at the point of delivery. In the concreting activity at site 2, reduction of cycle time ofconcrete work from 23 hours to 17 hours reduced the overall emissions by about 13%. Bettermobilization and planning of concrete activity can thus lead to positive impact on the carbon footprint.The reduction mainly comes about by eliminating idling of the miller at the location and promotingmore just-in time delivery.In the concreting activity at Site 3, reduction of cycle time from 22 to 18 hours showed a decrease ofonly 3% in carbon emissions. This is because the process was already quite efficient except for a fewlogistics problems. By mitigating them the process becomes more efficient and greener.11 Page
  12. 12. 8. Finishing activities Block work: - The current state map of the block work activity at site 2 showed that, the major „lean‟ perspective problems were inventory at the ground and deficiency or waiting for blocks at the top floor. Meeting the demand of blocks called for an alternative or parallel mechanism to transfer the blocks. A management solution could not solve the problem and hence a more technical approach that proposed the use of a crane to minimize the „lean‟ wastes of inventory and waiting was suggested. This had a positive effect on both the cycle time as well as the carbon footprint. The cycle time per cycle (45 blocks transport and placing is one cycle) reduced by 60 minutes. Overall cycle time for the whole activity reduced from 12 hours to 10 hours. So from the „lean‟ perspective using a crane is justified because it promotes flow of work. Here focus was on the equipment used to transfer the blocks i.e. a crane has to work only 10 hours while the hoist will have to work 20 hours to transport same number of blocks. In this case it was observed that using a crane yielded lower carbon emissions (18% lower) than when the hoist was use. But if we consider the cost and footprint associated with mobilizing a crane for the activity it is very clear that it is not a „green‟ option. But in a situation where a crane is available for use at site and if it can be applied for the activity, it serves the „Lean‟ and „green‟ purpose. However a contradictory finding here was that the „per hour carbon emissions‟ of a crane is much larger (38%) than a hoist. So the number of working hours of the equipment is the key factor to be considered here. Structural steel Fabrication and erection: - Overall in the structural steel process the flow was well maintained and the current state map reflected a „Lean‟ process. But the major issue was the non- availability of civil work front for erecting the truss work. This caused inventory at site, damage during storage and rework resulting in additional emissions due to rework. Observing the activity showed that the work flow plan of the activity had to be improved. All the sub-activities were initially in the same place in a line. But due to site restrictions, the work flow area had to be distributed and certain sub-activities had to be shifted to different locations at site, which called for more transport. Mitigating this transport waste could bring a reduction of 3% carbon emissions. It was also observed that the material waste (Wastage due to cutting and grinding) could be reduced from 25% to 13% by using properly customized steel sheets other than the standard market available sheets for work. In terms of embodied energy, it reduces the carbon footprint by 22 % which is quite huge. This shows that proper technical expertise of the activity as well as consideration of workflow can design a perfect process. 9. Conclusion Table 2:-Summary of Results ACTIVITY Cycle Time Reduction Due To ‘Lean’ approach Reduction In EmissionsPiling (1 pile) 1.35 hours 16%Open foundation (1 foundation) 3 hours 26%Concreting of slab at site 2 (360cum) 6 hours 13%Concreting of slab at site 3 (500 cum) 4 hours 3%Block work (800 blocks working) 2 hours 18%Structural steel fabrication(one truss) (In the order of days) 3% Table 2 summarizes the results obtained for each activity observed. From the study it was observed that concreting activities had a major impact on the carbon footprint. Activities which involved 12 Page
  13. 13. concrete delivery on site showed larger footprints owing to the large amount of transportation ofmillers. It is difficult to generalize that a certain stage of construction or activity has a largerenvironmental impact than others. But it is clearly observed that the transportation at site has thelargest and most direct impact on the environmental footprint. This is because; most of theconstruction equipments are used for hauling or shifting purposes. Reducing unnecessary movementat site should be a focus area. Inventory has the lowest impact in the perspective of equipments ofmachines because; machines when idle don‟t create any emissions. „Waiting‟ wastes implies to whenequipments like concrete trucks are kept waiting at the concrete delivery points without unloading.This is mainly because of improper planning and mobilization of the works. The equipment in-chargeand site engineers should ensure that the equipments are used judiciously and site preparations for awork are done before the start of the work,„Lean‟ and „Green‟ can be concluded to have a direct and positive linkage. This linkage can beunderstood clearly from the study because carbon footprint calculation acts as the measurablequantity of this linkage. Reduction in carbon emissions as a process becomes „lean‟er shows that thestrategies are strongly correlated. Other than implementing costly technical improvements andinnovations to achieve sustainability, the application of the „lean‟ production concept which includes aseries of management practices that do not involve high investment costs, will help to achieve betterperformance and environmental sustainability. „Green‟ design and „green‟ products are not justenough to make construction eco-friendly; the facility should be delivered in a „green‟ manner. Betterconstruction should be the focus of the time and „lean‟ provides a firm platform for the same.Future study in the area linking „lean‟ and „green‟ could be focused on finding the impact of various„lean‟ tools on the environment. Considering the effect of „lean‟ on „sustainability‟ i.e. not justenvironmental aspect but the economic and social aspect, would be a promising research. This studyonly considers equipment emissions while a comprehensive study requires calculation of embodiedenergy of materials and other minor tools as well and it will show a better picture of the „Lean‟ and„Green‟ linkage.10. References1. Bae J. and Kim Y. (2008). “Sustainable Value on Construction Projects and Lean Construction”. Journal of Green Building, 3, 156-167.2. Clarice Menezes Degani and Francisco Ferreira Cardoso(2002). “Environmental performance and Lean construction concepts: can we talk about a clean construction”. Proceedings IGLC,10, Brazil.3. Hendrickson, C. & Horvath, A. (2000). “Resource use and environmental emissions of U.S. construction sectors”. Journal of Construction Engineering and Management,ASCE, 126(1), 38– 44.4. Horman, M. J., Riley, D. R., Pulaski, M. H., and Leyenberger, C. (2004), “ Lean and green: Integrating sustainability and lean construction,” CIB World Building Congress, May 2–7, Toronto, International Council for Research and Innovation in Building and Construction , The Netherlands.5. Horvath, A. (2004), “Construction materials and the environment”. Annual Review of Environment and Resources, 29, 181–204.6. Howell and Ballard (1998), “Implementing Lean Construction: Understanding and Action”,Proceedings IGLC ’98, Brazil.7. Isabelina Nahmens, Laura H. Ikuma, (2011),”Effects of Lean on Sustainability of Modular Homebuilding”, Journal of Architectural Engineering, ASCE.13 Page
  14. 14. 8. Jensen, W. &Kouba, A. (2007),“The role of the contractor in sustainable construction”.The American Professional Constructor, 31(1), 18–22.9. Kibert, C. J. (1994),“Final session on sustainable construction”, Proceedings of the first international conference of CIBTG 16. Tampa, Florida.10. Kibert, C. J. (2007),Sustainable construction: Green building design and delivery. 2nd ed., Hoboken, NJ: John Wiley & Sons.11. Klotz L., Horman M. and Bodenschatz M. (2007). “A Lean Modeling Protocol for Evaluating Green Project Delivery”. Lean Construction Journal, 3, 46-6412. Lapinski, A., Horman, M., and Riley, D. (2005). “Delivering sustainability: Lean principles for green projects," ASCE Construction Research Congress (CRC), 36–140.13. Lapinski, A., Horman, M., and Riley, D. (2006) “Lean processes for sustainable project delivery”, Journal of Construction Engineering and Management, 132(10) pp. 1083-1091.14. Luo, Y., Riley, D., and Horman, M.J. (2005). “Lean Principles for Prefabrication in Green Design- Build (GDB) Projects”. Proceedings of IGLC-13, 18-21.15. Nahmens, I. (2009) From Lean to Green Construction: A Natural Extension. Conference Proceeding Paper Building a Sustainable Future. Proceedings of the 2009 Construction Research Congress, pp. 1058-106716. O. Salem, J. Solomon, A. Genaidy, and M. Luegring (2005, “Site Implementation and Assessment of Lean Construction Techniques” , Lean Construction Journal, (vol.2), October 2005.17. Ohno, T. (1998). Toyota Production System-Beyond Large Scale Production. Cambridge, MA: Productivity Press18. Palaniappan, S., Bashford, H. H., Fafitis, A., Li, K., &Stecker, L. (2009), “Carbon emissions based on ready-mix concrete transportation: A production home building case study in the Greater Phoenix Arizona area”, Associated Schools of Construction 45th Annual International Conference, University of Florida, Gainesville, USA.19. Picchi, Flávio Augusto; Granja, A. D. (2004), “Construction sites: using lean principles to seek broader implementations”. Proceedings, 12th Annual Conference on Lean Construction, Elsinore.20. Rees, W. E. (1999), “The built environment and the ecosphere: a global perspective”. Building Research and Information, 27(4/5), 206–220.21. Riley, D., Magent, C., and Horman, M.J. (2004) "Sustainable metrics: A Design Process Model for High Performance Buildings”, CIB 2004 World Building Congress, Toronto, Canada.22. Rother, M., & Shook J. (2003). “Learning to See: Value Stream Mapping to Create Value and Eliminate Muda”,The Lean Enterprise Institute,Brookline, MA.23. U.S. Environmental Protection Agency (2003). “Lean Manufacturing and Environment”. http://www.epa.gov/lean/performance/index.htm [accessed 12/08/2011].24. USGBC (U.S. Green Building Council). (2008), “Green building research and benefits”, url:http://www.usgbc.org/DisplayPage.aspx?CMSPageID=1718[accessed December 30, 2011].14 Page
  15. 15. 25. Wang Guangbin, Guiyou and Bian Li (2011), “Sustainable Construction Project under Lean Construction Theory”, Advanced Materials Research (Volumes 250 - 253), http://10.4028/www.scientific.net/AMR.250-253.3345, [accessed 12/08/2011].26. Womack, J. and Jones, D. T. (1996), “Lean Thinking: Banish Waste and Create Wealth in YourCorporation”,Simon and Schuster, New York.27. Wu, P. and Low S.P. (2011),“Lean production, value chain and sustainability in precast concrete factory – a case study in Singapore”,Lean Construction Journal, pp 92-109.28. http://www.secbe.org.uk/sustainable_construction15 Page
  16. 16. 11. Author’s Profile I am a civil engineer by profession. I have completed my B- Tech in Civil from M. A College of Engineering, Kothamangalam, Cochin. I have done my M-tech in Construction Technology and Management from IIT Madras. Presently I am working as a Planning engineer at L&T construction in an ongoing project at Gujarat. The paper is a based on the one year research work done as part of my M- tech project. Email: ann.fra12@gmail.com16 Page

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