Xin Zhao
email: zhaox@cei1958.com

Yonggao Fu

Jiaqi Hu

Ling Wang
email: wangl@cei1958.com

Meiling Deng

The reverse logistics technology and development trend of retired home appliances

Keywords: retired appliance, reverse logistics, development trends

This paper has introduced the status of retired home appliances reverse logistics industry in China , elaborated the key technologies which need to be focused on to enhance the development level of reverse logistics industry, including product life cycle information tracing technology , retired product quality detection technology , inventory optimization control technology, to build efficient reverse logistics information system and lead the industry to develop in the direction of informationization and standardization.

Introduction

China is the world's biggest home appliance manufacturing country, has a huge number of home appliances ownership. According to data from the National Bureau of Statistics, our country's social ownership of TV sets, refrigerators, air conditioners, washing machines, computers reached 1.5 billion units in 2011 .Faster product replacement product life cycle has been reduced each year due to end-of-life , out of substandard products returned loss is growing at a phenomenal rate . Because of the faster product update speed, shorter product life cycle, the loss caused by discarded, obsolete, unqualified products return is growing at an alarming rate each year.On the other hand, as people's environmental awareness is growing, the government began to require manufacturers to be responsible for the whole process of the product life cycle with legislation, especially in the recycling of waste product."Waste electrical and electronic product recycling management regulation " has formally implemented from the year of 2011, this regulation improves the threshold of waste electrical and electronic products industry, makes the responsibilities of production enterprise , sales enterprise , recycling enterprise, handling enterprise clear .The implementation of this regulation has the significance of the milestone type on the development of the recycling of waste electrical and electronic products industry. Reverse logistics is still a new industry in China , but it can reduce costs , improve the economic efficiency of enterprises , enhance their competitive advantage , improve the living environment of mankind , promote sustainable development , these advantages has attracted the attention of enterprises , so the retired home appliances reverse logistics industry has developed rapidly [START_REF] Gan | Reverse logistics[END_REF] .

The Development Status of Reverse Logistics Technology

The research for retired home appliances reverse logistics in china focuses on the following aspects: [START_REF] Huang | The reverse Logistics Management[END_REF] (1)reverse logistics network design research, which mainly studies network structure characteristics and the construction of model of reverse logistics ; (2)inventory control and management research, which discusses how to the process inventory management of recycled products efficiently and economically ; (3) the effective application of forecasting and decision technology in reverse logistics research ,which discusses effective treatment of forecasting and decision technology on uncertainty ,complexity and other factors which exist in the reverse logistics; (4) reverse Logistics Information System research , which analyses the structural characteristics of the reverse logistics system, studies the building of reverse logistics information system.

Above research is basically limited to the theoretical level of mathematical modeling .As for how discarded home appliances characterize, identify and trace the full life cycle information, and how to realize the quality inspection and judgment of retired appliances quickly , to supervise the recycling process effectively , to build reverse logistics management information system are still a lack of systematic research .

The Classification and Labeling of Product

Due to the models, specifications of home appliance products circulating on the market are different at present, if just only trace the information of retired home appliances, it is more cumbersome, so the relevant government departments should study and define the encoding rules in the design, using and maintenance and other stages of the life cycle of home appliances, establish a special classification and coding system.

Recovery and inventory

At present, the waste home appliances recycling channels are still not perfect, which can be divided into three categories: First, the individual small traders purchase from door to door or at street , which is the most common way to recovery ; Second, the home appliances flea market or sales , recycling enterprises purchase and recover , including the successful home appliances enterprise's recovery; Third, organs and institutions trade unified , but this is a very small proportion . It should be based on the existing home appliances products (refrigerators, air conditioners, televisions, computers, washing machines) sales logistics platform and multidimensional recycling (contains a variety of recycled sources, such as scrap, return, fund management, etc.) network system to analyze the characteristics of reverse logistics in different ways, to determine the basic operation mode and technical requirements of reverse logistics.

Due to the connection and operation of reverse logistics is uncertain, it should build reverse logistics inventory control model which is suitable for home appliance recycling enterprise. First, considering the time and space factors impact on the overall cost of recycling , the analysis of the quantity drive and time drive mechanism in the recycling enterprise inventory management under the environment of uncertainty sources of quantity and quality . Second , as the demand of home appliance is fuzzy in the reverse logistics , it should through the analysis of the distribution processes of key materials, establishing fuzzy environment multicycle inventory control model , proposing inventory control strategy of the manufacturing enterprises under different conditions , to achieve effective coordination of inventory materials in reverse logistics system between the main enterprise . [START_REF] Dai | The recycling system and management mechanism of waste home appliances[END_REF]

Dismantling

To improve the enterprises' efficiency of dismantling, it should accord to the national retirement products, key product disassembly information label specification, to develop the monitoring and control system of information collection system and dismantling process, to realize the identification, collection and data analysis of the EX-warehouse and warehouse information of outbound products and inventory products, real-time tracking of enterprise internal operation, to provide technical means for government regulation .

Combining with the status , and under scientific planning, to promote the area construction of facilities for central treatment of waste electric and electronic products, improve the standardization processing capacity, site selection should be coordinated the planning of urban development, environmental protection, land and so on, should straighten out the dismantling households, sorting and dismantling field and other non-standard processing units, enter the centralized treatment plant which is planed and built by government within a definite time, implement unified management. [START_REF] Yam | The research of reverse logistics network site optimization strategy[END_REF]

Remanufacturing

China is home appliance consumption and production power country, electric and electronic products resources consumption of which is larger. Remanufacturing is refers to through the necessary disassembly, such as repair and replacement of parts, to recover the waste products such as the new process, which can effectively realize the recycling of resources, reduce unnecessary waste. Faced with limited resources and waste disposal capacity, remanufacturing as a senior form of product recycling, can effectively achieve the comprehensive target of optimization utilization of resources, environmental protection and economic sustainable development, has attached great importance to by the government and enterprises, become one of the most effective way to realize sustainable development. [START_REF] Yu | The production logistics simulation of the home appliances remanufacturing[END_REF] 3 Policy and measure China has carried out the law of "Cleaner Production Promotion Law of the People's Republic of China", according to the Decree 551 of the State Council of the People's Republic of China, since January 1, 2011, "The Management Regulations of recycling of waste electrical and electronic products", has also went into effect.

Guangdong Province for example, by the end of 2015, we forecast that the institutional mechanisms of recycling of waste electrical and electronic products in Guangdong Province are basically perfect, the construction of enterprises with centralized treatment of the four areas, such as the Pearl River Delta, Eastern Guangdong, Western Guangdong, Northern Guangdong, etc. The recycling network and unified norms regulatory system which covers urban and rural are basically established. [START_REF]Audit manual of waste electrical and electronic products dismantling situation[END_REF] Guangdong Province has carried out some specific measures as follows: Focus on strengthening the layout guide, and to build a large-scale centralized processing system, and to promote the cleaner production.

Implement national policies related to subsidies, improve the subsidy audit procedures, and transfer on time the subsidy funds, to speed up dismantling company capital return. Implement the preferential policies of corporate income tax of the comprehensive utilization of resources; provide the processing enterprises tax incentives of the operating income in accordance with the regulations.

Promote the use of recycling technology recommended by "China Resources Comprehensive Utilization Technology Policy", encourage the waste electrical and electronic products processing enterprises to adopt advanced technology and equipment, and conduct the upgrading of technological improvements and dismantling production line. Pursue the cleaner production audits; increase the resource recycling efficiency and the level of environmental pollution prevention and treatment, to build a cleaner production and park. Construct the renewable resources comprehensive utilization information Center, Technology Center, and Key Laboratory in each province, actively organize the development and application of the dismantling of waste electrical and electronic products and the new processes, new technology, new equipment of Pollution prevention.

2.Depending on the construction of network, to build industrialized recycling system and to encourage resource utilization Establish a network which covers the communication and exchange of province-wide waste electrical and electronic product recycling information, for the convenience of strengthening the exchange and feedback of information between enterprises. Authorities, organizations and enterprises should inform specific recycling enterprises of fixed asset retirement details, ensuring that electrical and electronic products can be delivered uniformly to qualified enterprises for its recycling and dismantling. Support Waste electric and electronic products processing enterprises to establish cooperation with manufacturing enterprises, importers, distributors and recycling enterprises, in an endeavor to jointly build a recycling industry chain between the upstream and downstream industries on the manufacturing, recycling , processing, and utilization of electrical and electronic products. Through the ordered links of the industry chain and the construction of renewable resources utilization system, improve the rate and levels of resource recovery.

3. By means of strengthening the supervision and management, improve and standardize the unified regulatory system, to ensure the harmlessness.

Strengthen and standardize the management of channels of recycling and circulation of waste electrical and electronic products, and gradually establish a unified and standardized, fair and orderly recycling and circulation order, with clear division. Establish the system of evidence record, filing, registration and management for the waste electrical and electronic product recycling, in order to regulate the auditing of amount of recycling and processing and the fund subsidy program.

Strictly supervise the recycling, transportation, storage and dismantling processes of waste electrical and electronic products , standardize the environmental behavior of dismantling and recycling process of waste electrical and electronic products. Crushing and sorting components, parts with toxic and hazardous substances should be conducted in the closed facilities. Waste gas,

dust and other pollutants should be collected and purified, to ensure that it reaches the discharge standards.

Summary

The benign development of reverse logistics of waste electrical and electronic product has caused great attention of the national, so individuals, enterprises, and government need to cooperate. Recycling and re-manufacturing not only reduces the cost of home appliances, but also solves the environmental problems caused by the accumulation of dangerous dismantling .It has an extremely important significance for the sustainable development of the economy. [START_REF]The national development and reform commission resource conservation and environmental protection department compiled[END_REF] In the technical method of reverse logistics applications, RFID and smart inventory have broad prospects, so the environmental and economic value can be increased by enhancing the efforts of application.


Richard Bank
email: rbank@sustainable-scf.org

Richard Murphy
email: rmurphy@murphywarehouse.com

Warehousing Sustainability Standards Development

Keywords: Supply Chain, Sustainability, Warehousing, Logistics

de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Motivation

Sustainability improvement in warehousing has not been receiving much attention in spite of significant interests to increase efficiencies and sustainability of supply chain logistics 1 . However, there are reasons to pay more attention to this area of industrial activity. This section describes the reasons from the economic, operational, and sustainability perspectives.

1 Supply chain logistics is a subfield of the supply chain management and refers to supply chain operations that deal with the storage, distribution, and transportation of product and work-inprocess. Warehousing in turn is commonly known among supply chain practitioners as a kind of operations dealing primarily with storage and distribution; however, warehousing has evolved to also provide manufacturing, assembly, and other value-added services.

Economic Perspective

Warehousing plays an important role in supply chain from the economic perspective. According to [1], supply chain logistics, which comprise inbound and outbound warehousing and transportation, account for more than $1.28 trillion or 8.5% of the 2011 US GDP. In addition, [START_REF] Armstrong & Associates | The Business of Warehousing in North America -2012 Market Size, Major 3PLs, Benchmarking Costs[END_REF][14] indicate that warehousing business alone was worth $120 billion in 2011 (roughly 10% of the total supply chain logistics). It is also the fastest growing segment of supply chain logistics industry. Since 1996, the compound annual growth rate of the segment is at 10.3% while in 2011 it grew three times the US GDP growth [14].

Qualitatively, warehousing, as part of the supply chain, plays an important role as suggested by the survey of more than 700 CEOs conducted by Accenture and United Nation Global Compact in 2010. The survey data reported: "96% of the CEOs indicated that sustainability should be integrated into all aspects of strategy and operations while 88% of them singled out the supply chain as an area of specific importance" [START_REF]Why a Sustainable Supply Chain is Good Business[END_REF].

Studies have also suggested that supply chain sustainability performance improvements positively impact other business operations. These types of business operation improvements have been described in the supply chain management study entitled "Why a Sustainable Supply Chain is Good Business" published by Accenture [START_REF]Why a Sustainable Supply Chain is Good Business[END_REF]. A joint study by five industry organizations also points out other promising aspects associated with sustainable supply chain management [START_REF]Forbes: If Sustainability Costs You More, You're Doing it Wrong[END_REF][START_REF]stitute for Supply Management, and Deloitte Consulting: Selected Sustainable[END_REF]. The study indicates that supply chain is a place where return-on-investment (ROI) on sustainability can be expected. The study also shows that organizations that engaged in sustainability with supply chain members saw a 21% increase in sustainable supply chain effectiveness.

Operational Perspective

Warehousing plays an important role in manufacturing from the operational perspective. This is evident from the fact that manufacturers, distributors, and retailers have shifted more activities to the warehouse [START_REF] Maltz | Warehousing: The Evolution Continues[END_REF]. According to [START_REF] Lieb | CEO Perspectives on the Current Status and Future Prospects of the US 3PL Industry[END_REF], automotive, grocery, and high tech/computers industry have been using third-party warehousing service providers (or contract warehousing service providers) extensively. In addition, the Reinventing American Manufacturing report [START_REF] Bonvillian | Reinventing American Manufacturing: The Role of Innovation[END_REF] identified the increase in distribution efficiency as one of the five key technology advances to transform US manufacturing.

Traditionally, warehouses provide flexibility and agility in the supply chain by providing flexible spaces (pay-per-use) to store large buffers of inventory (with low turnover rate). In fact, warehouses play an even larger role in maintaining the flexibility and agility, as manufacturing cycle time reduces, product life cycle shortens, and product mix and customization increase. This is commonly known as logistics postponement strategy [START_REF] Coletta | Cooperative Logistic Postponement, 7th International Meeting for Research in Logistics[END_REF]. According to studies in [START_REF] Maltz | Warehousing: The Evolution Continues[END_REF][START_REF] Regan | An Industry in Transition: 3PL in the Information Age[END_REF], warehouses provide several value-added services including packaging, labeling, marking, testing, assembly, manufacturing, maintenance, and recycling to name a few, in addition to simply storing and distributing product or WIP. These services or activities are better performed at the warehouse because it allows for parts ucts to be more efficiently ship an unassembled product ble and ship to local customer as unassembled products space than when they are houses allows parts and products to reach customer (point (higher responsiveness) that requires more frequent shipments in smaller batches. Warehouse va service is also advantageous for customization occurring inside supplies products in standard configuration try) which are more economical to ship Fig. 1. Product customization at warehouses

Sustainability Perspective

The following are the result in warehousing footprint and the need tions:

1. More activities are occurring inside the warehouse and material consumption 2. More automation ciency and agility 3. The number of ware sumption across warehouses 4. Concentration of new w consumption [15 the need for more sustainable warehousing operations houses. Although there is no specific accounting of warehousing sustainability contrib tion, its significance can be whole. For example, studies pending on the industry, supply chain logistics produces between 26 to over 50 pe the warehouse because it allows for parts (including packaging materials) efficiently shipped and managed (e.g., it is more economical to first unassembled product to warehouses at distribution points which then asse ble and ship to local customer as unassembled products typically use less shipping they are already assembled). In addition, the large number of war houses allows parts and products to reach customer (point-of-consumption) (higher responsiveness). For example, warehousing supports just-in-time production that requires more frequent shipments in smaller batches. Warehouse va advantageous for customized products. Fig. 1 shows the final occurring inside a Murphy Inc.'s warehouse where the manufacturer standard configurations (to multiple warehouses across the cou more economical to ship.

Product customization at warehouses

Perspective

The following are the economic and operational perspectives of warehousing warehousing playing significant role in the product manufacturing carbon to increase sustainability considerations in warehousing oper ore activities are occurring inside the warehouse leading to higher consumptions. More automation has been used inside the warehouse to achieve greater eff ciency and agility [START_REF] D'andrea | Future Challenges of Coordinating Hundreds of Autonomous Vehicles in Distribution Facilities[END_REF] leading to higher energy consumption. number of warehouses is growing. This can lead to more energy co across warehouses even if volume is unchanged. Concentration of new warehouses in urban areas that are closer to 15] and stringent urban waste and emission regulations the need for more sustainable warehousing operations in those new war Although there is no specific accounting of warehousing sustainability contrib can be inferred from the supply chain logistics contribution as For example, studies undertaken by manufacturers in [3][START_REF]Stonyfield Case Study[END_REF][START_REF]Hanes Carbon Footprint[END_REF] showed that, d pending on the industry, supply chain logistics produces between 26 to over 50 pe and prodit is more economical to first to warehouses at distribution points which then assemtypically use less shipping large number of wareconsumption) quicker time production that requires more frequent shipments in smaller batches. Warehouse value-added final product where the manufacturer (to multiple warehouses across the counwarehousing that significant role in the product manufacturing carbon in warehousing operaleading to higher energy to achieve greater effi-. This can lead to more energy concloser to points of and stringent urban waste and emission regulations lead to in those new ware-Although there is no specific accounting of warehousing sustainability contribufrom the supply chain logistics contribution as a showed that, depending on the industry, supply chain logistics produces between 26 to over 50 per-cent of Green House Gas (GHG). One may estimate the warehousing GHG contribution as proportional to the economic value.

In conclusion: Although sustainability improvements can benefit warehousing operations both from the economic and operational perspectives, there has been little effort so far to establish sustainability metrics, guidelines and practices for warehousing operation. The Sustainable Logistics Initiative (SLI) is a recently established industry initiative to address this void. The next section introduces SLI, which so far has developed a set of sustainability metrics and a software tool for sustainability characterization. The following section reviews related supply chain sustainability efforts and discusses how their results may be used as the basis to expand SLI.

Sustainable Logistics Initiative (SLI)

Sustainable Logistics Initiative (SLI) is a sustainability program developed and administered by the International Warehouse Logistics Association (IWLA) in conjunction with the Sustainable Supply Chain Foundation (SSCF), which acts as a thirdparty neutral verifier. The program enables IWLA warehousing service provider members to demonstrate to their customers and to the public that their facilities' environmental efforts are helping to make the supply chain more sustainable [START_REF]Logistics Management: Sustainability: IWLA announces the Sustainable Logistics Initiative[END_REF][START_REF]International Warehouse Logistics Association (IWLA) Sustainable Logistics Initiative[END_REF]. The key drivers for the SLI are: improving financial results, assisting the customer to meet sustainability requirements, meeting request for proposal (RFP) sustainability criteria, demonstrating environmental stewardship as a responsible corporate citizen, and showing corporate pride for current and potential employees. SLI participants, through an independent verifier and a software tool, can use SLI metrics to establish each facility's baseline and target sustainability performances for annual improvement. SLI currently uses four environmental metrics (1 to 4 below) and two social responsibility metrics (5 and 6) as shown below.

1. Electrical usage: Metric = KWH of electricity / sq.ft. / operational hours or FTE hours (annual) 2. Recycling: Metric = annual lbs. or tons of paper, cardboard, plastic and wood packaging waste / sq.ft. 3. Liquid Fuel Usage: Metric = annual propane BTUs used / number of forklift hours 4. Water consumption: Metric = gallon / sq.ft. / FTE hours 5. Employee Safety: Metric = OSHA 300 Total Recordable Incident Rate (TRIR) 6. Community Service: Metric = facility community service participation IWLA and SSCF have shared interest to enrich SLI's metrics and measurement capabilities related to energy and material consumptions. Possible enrichments include additional energy and material performance metrics, their measurement guidelines, and performance improvement best practices. Such enrichments are critical to the environment and bottom lines of warehousing companies and their supply chain partners. Next section discusses possible development directions and existing works that can be the basis for such developments.

Directions for Warehousing Sustainability Standards Development

Develop Warehousing-Specific Energy Management Guidelines

Warehousing-specific energy management guidelines can be developed based on the ISO 50000 series2 of standards [START_REF]ISO 50001: Energy management systems -Requirements with guidance for use[END_REF][START_REF]Measuring Energy Performance using Energy Baselines & Energy Performance Indicators Committee Draft[END_REF][START_REF]ISO 50015: Measurement and Verification of Organizational Energy Performance -General Principles and Guidelines[END_REF]. ISO 50001 defines basic terminology and a plan-do-check-act procedure for managing energy performance in an organization.

ISO 50006 provides a guideline for specifying performance indicators, data collection methods, measurement time period, and energy measurement baseline. ISO 50015, currently in committee draft stage, specifies the verification and validation guidelines for energy performance measurement. In other words, ISO 50000 series is a horizontal/industry-neutral standard, and each industry or organization needs to come up with its own specifics. For example, no specific metrics, e.g., for warehousing operations, are identified in these standards. In addition, specific guidelines for setting and normalizing performance baselines over a period of operation are needed for different types of warehouses performing different operations over different periods. Such guidelines provide the implementable details for the routine and non-routine adjustments -two important concepts defined in ISO 50015 that are necessary for an effective energy performance improvement program. These guidelines can also be extended to cover other types of resources, such as material and water.

Develop New Metrics

The repository of sustainable manufacturing indicators (SMIR) created at the National Institute of Standards and Technology (NIST) [START_REF]Sustainable Manufacturing Indicators Repository[END_REF] is a useful resource to expand the SLI metrics. It documents sustainability indicators3 for various types of resources from various industries. For example, a recent discussion with IWLA members has indicated that natural gas should also be considered as part of the energy consumption metrics. To address this requirement, more precise metrics than those currently defined in SLI could be developed based on the energy intensity indicator documented in SMIR. The energy intensity indicator allows the respective metric to consider all energy types consumed. SMIR includes over one hundred and thirty indicators covering five categories: environmental stewardship, economic growth, social well-being, technological advancement, and performance management. It is a reference resource when expanding the coverage of SLI metrics.

Develop Industry Benchmarks

Sustainability metrics typically only allow for internal benchmarking of sustainability performances over different periods of time or different internal facilities. External benchmarking between companies allow for companies to determine how they perform as compared to peers. Companies can use the benchmarking outcomes to decide whether and where to invest in sustainability improvements. However, data privacy is typically a concern. Approaches used in the EPA Energy STAR programs for automotive assembly plants and for warehouses can be the basis for cross-facility benchmarking [START_REF] Boyd | Development of a Performance-based Industrial Energy Efficiency Indicator for Automobile Assembly Plants[END_REF][START_REF]ENERGY STAR® Performance Ratings, Technical Methodology for Warehouse[END_REF]. However, the Energy STAR for warehouses characterize warehouses as buildings (as opposed to manufacturing plants) and only categorizes warehouses into dry vs. refrigerated [START_REF]The ENERGY STAR for Buildings & Manufacturing Plants[END_REF][START_REF]ENERGY STAR® Performance Ratings, Technical Methodology for Warehouse[END_REF]. As we discussed earlier, warehouses are involved in a wide variety of activities. Hence, the current characterization and categorization may be insufficient. Further studies about warehouse characteristics to categorize them into comparable groups and to identify independent, predictive variables are necessary.

The Automotive Industry Action Group (AIAG) also has an ongoing project to apply the Energy STAR methods to different kinds of automotive manufacturing plants. These plants, such as engines, transmission, and even part manufacturing plants, are heterogeneous in their activities similar to those of warehouses. Lessons learned from this effort will be leveraged within the SLI.

Develop Theoretical Minimum Quantification Model

Current practices and guidelines for energy management and other sustainability management, such as in ISO 50000 series, only establish baselines and identify opportunities for performance improvements based on energy consumption within a particular time period. The assumption is that areas with high energy consumption provide greater opportunity for energy performance improvement. However, this is not an energy saving opportunity in an absolute value, because in the area where both the energy consumption and energy efficiency are high, the opportunity for improvement is, indeed, low. A better indicator for an energy performance improvement opportunity is the energy efficiency. To quantify the energy efficiency of a warehousing operation or process, it is necessary to develop a theoretical minimum energy quantification model for the activity or process. Cullen et al. [START_REF] Cullen | Reducing Embodied Carbon through Efficient Design[END_REF] is an exemplary effort which utilized the notion of theoretical minimum to reduce energy consumption in steel and aluminum supply chains. Theoretical minimum may be established coarsely at the facility level as well as more specific at the process level. With theoretical minimums, companies can identify a gap with their actual consumption. Large gaps may indicate leaks/wastes or poor performance of equipment or systems. Best practice guidelines can be adopted from the energy efficiency measures identified in [START_REF] Galitsky | Energy Efficiency Improvement and Cost Saving Opportunities for the Vehicle Assembly Industry[END_REF] or developed to minimize those gaps.

3.5

Connect with Other Nodes in the Supply Chain

The EPA SMARTWay program assists and encourages fuel efficiency and emission reduction specifically in freight companies [23]. The program provides tools to support three freight company roles in the supply chain: the shipper, carrier, and logistics provider. Because the tools connect the fuel efficiency data from one role to another, they allow companies in each role to choose partners based on their efficiency data. Since the tools only consider transportation, SLI may add a warehousing provider tool to include energy efficiency related to warehousing operations. With such addition, warehousing customers who use the SMARTWay tool can more conveniently and completely quantify and optimize the energy performance of their supply chain logistics.

Conclusion and Remarks

Warehouses and their operations are expanding as they are asked to increasingly perform value-added services to help customers reduce costs and increase agility and responsiveness. Therefore, they play an increasingly significant role in improving the manufacturing and supply chain sustainability. Sustainability performance metrics, associated measurement guidelines, and sustainability improvement best practices should be developed in order to effectively improve sustainability. The warehouse industry has started such development that resulted in an initial set of metrics and a sustainability characterization tool. Further developments are necessary so that sustainability improvements can be realized in both large and small warehouses and deliver impact across the industry. To that end, this paper has outlined further directions in which the warehouse industry can pursue in conjunction with the SLI. . In addition, existing standards and approaches related to sustainability management, metrics, and guidelines that can form the basis for such further development directions have been provided. Although there are no specific metrics and guidelines for warehousing operations, these existing efforts have been found to be potentially useful resources.

ISO 14000 series provide similar information for environmental management system.

Term 'indicator' can be viewed as more general/abstract than the term 'metrics'. For example, energy intensity indicator refers to a kind or collection of sustainability performance measurement. On the other hand, energy intensity metrics refers to a sustainability performance measure that is specific, e.g., to car manufacturing (an energy intensity metrics maybe BTU/per car), a warehousing operation (an energy intensity metrics maybe as defined in #1 in section 2).

Acknowledgement

The authors wish to thank Dr. Serm Kulvatunyou at the National Institute of Standards and Technology (NIST) who provided valuable new ideas and insights into a number of related activities and existing works in the supply chain sustainability.


Christopher Peters
email: cpeters@thelucrumgroup.com

Supply Chain Interoperability Efforts Missing Key Data

Keywords: Supply chain, supplier networks, interoperability, manufacturing

True manufacturing supply chain interoperability-where the assembly, reconfiguration and reconstitution of supply chains are done with minimal effort, time or cost-can dramatically alter the way that business is done today. Much of the existing research on supply chain interoperability focuses on established trading partners. However, we must consider both the sourcing and connecting processes in order to create true, dynamic supplier networks that can be easily assembled, reconfigured or reconstituted. This paper identifies why this is important, presents key challenges and proposes additional research that is needed to fill in the gaps.

Introduction

Manufacturing supply chain interoperability efforts are missing key data that must be addressed if manufacturers are to achieve the vision of fluid, dynamic supplier networks. Much of the existing research focuses on supply chain interoperability between established supply chain participants. In many cases, the supply chain is considered to be "interoperable" if the participants are connected at the data, service, process and business levels. (Veronica Pazos Corella, 2013) (Ray & Jones) What happens when new supplier networks need to be assembled, or when new participants must be added to existing supplier networks to increase capacity or replace a lost supplier? How does someone first locate a manufacturer with the right capabilities and capacity at the right time? How do they then know that the new participant's systems and processes will fit with those of the existing supplier network participants? Finally, what effort will be required to "onboard" the new supplier-that is, to connect the supplier's data, services, processes and businesses?

The missing data is how to efficiently source and seamlessly connect to new trading partners. It is this capability that helps manufacturers move from their reliance on static supply chains of existing partners to dynamic supplier networks, which can easily be assembled, reconfigured or reconstituted. The following definition, which is a variation on other commonly used definitions, is proposed to support that approach.

"Supplier network interoperability is the property of an organization, whose capabilities and interfaces are completely understood, to work with other organizations, present or future, without any restricted access or additional implementation."

Unfortunately, there is little research to fully flesh out this challenge, particularly for the unique demands of complex manufacturing supply chains. This paper identifies the various issues and the work that is needed to advance efforts in this area.

Motivation

The benefits of addressing and solving these challenges can yield significant value to both buyers and suppliers of manufactured goods. Challenges ranging from increased personalization to demand fluctuation and sourcing closer to the point of consumption can't be met easily with today's inflexible supply chains. Supply chain risk mitigation strategies also are limited today and could change dramatically if the time and effort to add or substitute suppliers were slashed. In short, achieving a "plug and play" supplier network-where new supplier networks can be assembled and new participants added or substituted at very little cost and with minimal time or effort-would change everything. Examples of specific benefits include:

• More quickly field new products;

• Readily secure capacity closer to the point of demand;

• Easily add capacity to meet demand fluctuations; and • Recover immediately from supply chain disruptions.

Manufacturing supply chain interoperability challenges

The process of sourcing (locate, evaluate, query, qualify, negotiate and contract) and connecting (data, services, processes and businesses) new trading partners is costly and time-consuming. Many companies simply work with the same base of suppliers over and over again to avoid these issues. In addition to limiting supply chain flexibility, this approach also limits the ability to apply pricing pressure and stifles innovation. Following are some of the specific challenges for various steps in sourcing and connecting manufacturing supply chains.

Sourcing a manufacturer (Locate, evaluate)

This challenge is compounded by the fact that there are a number of considerations to even begin choosing a manufacturer. For instance, standard questions determine if potential suppliers have:

• The tools and experience to work with the specified materials;

• Equipment to handle the size and tolerances required; and

• Skill sets and certifications to help ensure quality and delivery.

Beyond the basic requirements, buyers today are looking for increasingly sophisticated information to help them make sound sourcing decisions:

• Are supplier facilities close to the desired point of manufacture, distribution or consumption? • Does the supplier have sustainable practices?

• How well does the supplier collaborate and innovate?

Identifying and quantifying some of these considerations just to help locate and evaluate firms to be included in sourcing efforts can be very difficult. First, there is the mismatch between the description of a buyer's need and a manufacturer's capability. There then are the challenges of disparate formats and terminologies, often describing the exact same process or capability.

Sourcing a manufacturer (Query)

Once a target list of manufacturers is identified, prospective suppliers must be queried to gather key information. This query is typically a sourcing event, such as a request for quote (RFQ) or request for proposal (RFP). In the past, the buyer was often focused on price, quality and delivery. However, buyers today increasingly are seeking information that has no standard definition and is not included in common electronic data interchange (EDI) or Extensible Markup Language (XML) schema. For example, specific technical capabilities, information on sustainable practices and innovation experience are becoming increasingly important when selecting manufacturers.

There are a number of challenges to effectively sourcing manufacturers. The first is just sending an RFQ that all recipients can open, interpret and respond to in a consistent manner. While that would seem simple with today's technology, there is still considerable effort involved. Each buyer's RFQ format is different and quite often requires clarification and augmentation before a supplier can provide a quote. (In fact, many manufacturers still send RFQs and technical data via fax, mail and email.) The second challenge is clearing the hurdles around technical data, which can include formatting, intellectual property control and translations.

Sourcing a manufacturer (Qualifying)

A major hurdle in working with a new manufacturer is the qualification process. This challenge is particularly important to industries with complex products, such as aerospace, defense, automotive, medical equipment and others. One of the most typical, but least efficient, qualification means is to conduct an onsite visit to gather information about past performance and document processes, skill sets and equipment capabilities. While this qualification process often is crucial to help ensure the supply chain delivers quality goods on time, the process inhibits exploration of new partners.

Some work has been done to identify how an "interoperability potentiality measure" could help determine the level of effort required to work with a new partner. (Chen, Vallespir, & Daclin, 2008) However, this approach is still in the nascent stages and primarily focuses on the conventional aspects of interoperability for data, services, processes and business. Product interoperability standards (Will this supplier's product meet my requirements and be delivered on time for the right price?) have not been adequately addressed.

Connecting a manufacturer

Once each manufacturer is chosen (remember that assembling a supply chain is often a serial process), the effort begins to connect each to enable the "Three C's" of successful supply chains: communication, coordination and collaboration. When you consider that complex supply chains can contain hundreds or thousands of suppliers, this is a daunting task.

Immediately, the supply chain has to begin exchanging data for technical requirements, demand and production to begin aligning processes, such as sales and operations planning or financial reporting. There then is the issue of coordinating task timeframes and responsibilities, and determining what metrics will be used and how they'll be reported.

All of this must be done with data that have different definitions and formats and come from disparate software programs. In fact, a recent study identified that "more than 50% of the information exchanged between business partners travels over fax, email and phone rather than flowing directly between business applications via B2B integration technologies such as EDI and XML." [START_REF] Gillai | B2B Managed Services: Business Value and Adoption Trends[END_REF] Even those companies that use EDI or XML typically require an effort to align definitions and formats.

Promising efforts currently underway

There are very interesting pockets of innovation that are addressing some of the challenges in assembling and coordinating complex manufacturing supply chains.

OAG -Standard Manufacturing Service Capability Model

A new Open Applications Group (OAG) activity is being initiated to advance computer-interpretable communication of manufacturing information. For the purpose of initial analysis, manufacturing information necessary to enable contract manufacturing and custom parts ordering within the supply chain is investigated. The goal of the activity is to achieve greater automation in processing manufacturing information, which is typically (1) carried in the RFQ and other electronic documents and (2) exposed online by manufacturing suppliers. The manufacturing information may include manufacturing process capability information, manufacturing information processing capability information (software capability), product functions and product design features. [START_REF] Ivezic | Advancing Computer-Interpretable Communication of Manufacturing Information[END_REF]

NIST -Manufacturing Services Network Models Project

The National Institute of Standards and Technology (NIST) is conducting a project to enable small-to medium-sized enterprises (SMEs) to more readily participate in advanced production networks. Following their discovery and qualification, SMEs need to be able to receive and use digital manufacturing data and effectively respond to the requests to make the parts. The Manufacturing Services Network Models Project aims to provide cutting-edge semantic model development and an evolution methodology that allows for rigorous development of a semantic-rich standard for representing and communicating manufacturing service capabilities, including material processing and manufacturing information processing capabilities. Project deliverables include reference models, methods and tools to support the manufacturing service capabilities standard development. [START_REF] Kulvatunyou | Enhancing Communication of Manufacturing Service Capability Information[END_REF]

KITECH -i-Manufacturing

South Korea's KITECH organization has developed a collaborative manufacturing platform that essentially allows its SMEs to plug in once and connect to many, regardless of disparate systems. Started in 2004, this system facilitates supply chain collaboration for more than 1,000 companies across multiple manufacturing supply chains. While its initial focus was on the molding industry, it is quickly expanding into other industries and delivering quantitative benefits that include a 33% reduction in time and a 16% reduction in costs.

Research that is needed

There is plenty of anecdotal evidence to support these challenges. However, there is very little in the way of quantitative evidence to identify just how bad the problem is and help provide direction and priorities for solving the challenges. This is particularly important to help manufacturing supply chains become more globally competitive.

Research Need #1 -Quantify the process inefficiencies

The first step should be to quantify the time and effort required to perform the sourcing and connecting tasks today. As the results will vary by industry, manufacturing complexity and other factors, a framework should be developed that would accommodate and capture those differences. This effort must look across all nodes of a supply chain, as there will be differences at the various tiers. Finally, manufacturers must understand the impacts of those inefficiencies, particularly on products and production, and identify how companies currently negate them.

Research Need #2 -Identify information flow details

Streamlining the effort to source and connect new manufacturers requires understanding what information is needed for these tasks and how that information is exchanged today. This is particularly important for the volumes of unstructured data that are required to source and connect to new suppliers. Due to the complexities of manufacturing supply chains, there are numerous issues beyond what is normally contained in EDI or XML schema, such as the exchange and protection of technical data and the collaboration around it.

5.3

Research Need #3 -Build the business case

Once the "as-is" picture is understood, a case needs to be made for the "to-be" scenarios. Some of the easiest projections will be simple reductions in cost and time. However, the greatest business opportunities won't be as readily obvious or as easily quantified. Some examples of revised thinking include the following:

• Could the need for and trappings of long-term agreements be negated?

• Can pricing and volume be decoupled, making feasible a lot size of one?

• How does complete supply chain flexibility alter product customization?

• What risk mitigation strategies are best if adding new suppliers is frictionless?

Summary

True manufacturing supplier network interoperability-where the assembly, reconfiguration and reconstitution of supplier networks is done with minimal cost or effort-can dramatically alter the way that business is done today. However, achieving truly dynamic supplier networks requires a considerable amount of work. In fact, the National Coalition for Advanced Manufacturing (NACFAM) wrote about these very issues in "Exploiting E-Manufacturing" in 2001, yet little progress has been made todate. (National Coalition for Advanced Manufacturing, 2001) Despite all of today's advanced technology, the assembly and coordination of manufacturing supply chains is still very inefficient. While most people in the manufacturing industry can share many anecdotal tales that illustrate these inefficiencies, the industry does not have solid, quantitative evidence of the impact on products and production. Such evidence would be an eye-opener for many and can help identify where the needs are the greatest.

The really exciting opportunity is to identify how dynamic supplier networks could be assembled and coordinated in the future. If all information is interoperable, will modeling and simulation agents be able to analyze myriad permutations to design a supplier network that yields the best product for the consumer while optimizing production and profits for the suppliers? Will technology facilitate the design and assembly of unique supplier networks for each order? Will we reach a point where suppliers can be added or swapped out of supplier networks with little time, effort or cost? Building a sound business case for a future vision of dynamic manufacturing supplier networks will provide the industry with a roadmap of what needs to be done to achieve that vision.


Florian Tietze
email: florian.tietze@tuhh.de

Hermann Lödding
email: loedding@tuhh.de

State-oriented productivity analysis in one-of-a-kindproduction

Keywords: one-of-a-kind production, productivity analysis, lean management

Traditional productivity analysis has emerged in mass production and cannot be adopted one-to-one on One-of-a-kind production (OKP). Due to the non-repetitive character of the processes in OKP, productivity improvements do not reproduce like in mass production. In addition, preparatory activities such as orientation, material handling and positioning usually consume a lot more time than the actual value-adding activities in OKP. Therefore, OKP requires analysis methods that deliver: 1) a generic working cycle to enable repetitive productivity improvements; 2) activities of personnel in production processes, which include the preparatory activities. We introduce a state-oriented approach for productivity measurement in OKP. With a case study we show how to capture, visualize and evaluate state data of an OKP.

Introduction

Methods of lean production facilitate a systematic approach and have enabled large productivity gains primarily in mass production [START_REF] Roos | The Machine That Changed the World: The Story of Lean Production[END_REF]. In one-of-a-kind productions, the use of many methods of lean production is hardly practicable because the processes rarely repeat [START_REF] Salem | Lean Construction: From Theory to Implementation[END_REF]. The materials, sequence, location, necessary tools as well as the position of parts are changing significantly more often in an OKP. That is why the percentage of manual activities is higher. Analyzing and improving the productivity of these labor-intensive processes is a crucial task for these companies [START_REF] Ohno | Toyota Production System -Beyond Large-Scale Production[END_REF]. This paper presents a methodology that enables companies with OKP to analyze the influencing factors of the labor productivity with relatively low effort. The focus is on data collection. This is based on the definition of worker activities, objects and a generic working cycle and enables the aggregation of productivity data across various departments and processes. The analysis of the data allows to compare the different factors of productivity and to prioritize improvement activities. An industrial example shows that the method is suitable to analyze OKP and the influences on the labor productivity in detail. The method claims to be valid for universal OKP, although the case is taken from the maritime industry.

One-of-a-kind Production

Production as well as the assembly can be divided according to different types. In this context, mass production and one-of-a-kind production are the two extremes [START_REF] Gruß | Schlanke Unikatfertigung -Zweistufiges Taktphasenmodell zur Steigerung der Prozesseffizienz in der Unikatfertigung[END_REF].

Within mass production, products are highly standardized. All relevant information is available from the start of production. As a result of the many repetitions, process improvements lead to high productivity growth.

The OKP with its highly customized product needs a high flexibility of production processes and high reconfigurability of the used equipment. The following organizational principles are typically used [START_REF] Wiendahl | Betriebsorganisation für Ingenieure[END_REF]: manual production workshop, construction site principle, flexible manufacturing cells. The OKP is characterized by several features [START_REF] Piller | Mass Customization[END_REF]: i.e. higher secondary times, long lead times, low transparency of business processes, complex production control and more.

These properties of the OKP lead to low productivity, which is reflected in a different structure of the working time. In mass production, workers spend a huge amount of time directly at the product. In OKP, workers spend an essential time for the acquisition of information and organization of work patterns.

Due to this focus, many methods of lean production cannot be applied directly. Moreover, the lack of transparency as well as the less detailed and not standardized work processes makes it more difficult to analyze the productivity. The various types of manufacturing in the OKP, the parallel processes and the complex production control complicate the prioritization and implementation of improvement activities.

The following section provides an overview of different approaches aiming at the analysis of productivity in industrial companies.

Productivity Analysis

A productivity analysis examines a production process normally at defined time intervals to detect productivity potentials [START_REF] Nebl | Produktivitätsmanagement. Hanser[END_REF]. Different approaches for productivity analysis exist:

• Empirical productivity analysis: Productivity indices [START_REF] Craig | Total Productivity Measurement at the Firm Level[END_REF], econometric models [START_REF] Sudit | Productivity measurement in industrial operations[END_REF] and methods of linear programming [START_REF] Charnes | Measuring the efficiency of decision making units[END_REF] belong to the empirical productivity analysis. Overall, these approaches are not effective in the OKP, because they provide abstract results based on theoretical assumptions and the heterogeneous causes of lost productivity cannot be identified or associated with the losses. • Operative methods: Methods-Time Measurement [START_REF] Bokranz | Produktivitätsmanagement von Arbeitssystemen[END_REF], SMED [START_REF] Shingo | A Revolution in Manufacturing: The SMED System[END_REF] and Primary-Secondary-Analysis [START_REF] Lotter | Primär-Sekundär-Analyse: Kundennutzenmessung und Kundennutzenorientierung im Unternehmen[END_REF] provide a high level of detail. However, for the OKP this productivity analyses are limited, because the operations are not sufficiently planned in detail and the processes are repeated rarely.

This overview shows the lack of productivity analysis in OKP, since most of the methods serve rather abstract level and often require high data acquisition and operational effort. Thus, productivity analysis in the OKP has to fulfill the following requirements:

• The productivity analysis must be flexible in different types of production.

• Losses during preparation and other ancillary activities must be included.

• The methodology should enable repeatable productivity gains.

• The results of the analysis sho

Concept of a state

Based on the requirements described for productivity analysis in OKP the procedure of a state-oriented productivity analysis will be explained. These efficie tivity analysis have mainly been applied to machines or interlinked manufacturing systems [START_REF] Wiendahl | Produktivität komplexer Produktionsanlagen[END_REF][START_REF] Grando | Modelling plant capacity and productivity: conceptual framework in a single-machine case[END_REF]. The worker states need to cover the whole time time to realize a comprehensive analysis. Value adding tasks can equally be a source fo the methodology for the productivity management in OKP.

Fig. 1.

It combines various sub scope of this paper is limited to the first four sub tion, data aggregation and data evaluation. In order to describe the operation of the methodology, the following section describes the predefined inputs and methods.

Worker Activity and Object Hierarchy

Mixed production types, few standard activities and higher secondary and setup times make it difficult to describe the operational procedure in OKP in a s Fruehwald developed a method to standard method, one process step is fully described by combining an object with an activity. The result is a worker activity and object hierarchy as shown in fig.

The productivity analysis must be flexible in different types of production.

Losses during preparation and other ancillary activities must be included. The methodology should enable repeatable productivity gains.

The results of the analysis should allow prioritization of improvement actions.

Concept of a state-oriented Productivity Analysis

Based on the requirements described for productivity analysis in OKP the procedure oriented productivity analysis will be explained. These efficiency or produ tivity analysis have mainly been applied to machines or interlinked manufacturing ]. The worker states need to cover the whole time span of paid labor time to realize a comprehensive analysis. Value-adding tasks as well as non adding tasks can equally be a source for reduced labor productivity [START_REF] Czumanski | Integral analysis of labor productivity[END_REF]. Fig. 1 shows the methodology for the productivity management in OKP.

. Methodology for productivity management in OKP various sub-methods, which are linked with inputs and outputs. The scope of this paper is limited to the first four sub-methods: Modification, data acquis tion, data aggregation and data evaluation. In order to describe the operation of the e following section describes the predefined inputs and methods.

Worker Activity and Object Hierarchy

ixed production types, few standard activities and higher secondary and setup times make it difficult to describe the operational procedure in OKP in a standardized way. Fruehwald developed a method to standardize flexible set-up processes [START_REF] Frühwald | Analyse und Planung produktionstechnischer Rüstabläufe[END_REF] , one process step is fully described by combining an object with an activity. The result is a worker activity and object hierarchy as shown in fig. 2.

The productivity analysis must be flexible in different types of production. uld allow prioritization of improvement actions.

Based on the requirements described for productivity analysis in OKP the procedure ncy or productivity analysis have mainly been applied to machines or interlinked manufacturing an of paid labor adding tasks as well as non-value-]. Fig. 1 shows methods, which are linked with inputs and outputs. The methods: Modification, data acquisition, data aggregation and data evaluation. In order to describe the operation of the e following section describes the predefined inputs and methods.

ixed production types, few standard activities and higher secondary and setup times tandardized way. 7]. In this , one process step is fully described by combining an object with an activity.

Fig. 2.

The worker activities are clustered in groups and structured with a numerical logic. To identify the worker activities and to minimize the data acquisition ef worker activity has an individual number, which implies the main and sub group. The same logic structures the object hierarchy. As a result each unique worker state can be described with a combination of an activity and an object.

Modification and Worker State Matrix

The combination of the worker activity and object hierarchy ity and object matrix. combinations. There are two reasons for an invalid activity/obj

• Technical and logical inconsistency: E.g., it is not possible to screw a colleague.

• Definitive inconsistency: It is invalid to screw a section, because small parts like clamps are screwed on large parts.

It may be necessary to modify the worker activities are universally valid and have to complement only in special cases. However, the objects have to be adapted to the neric matrices for industries

Data Acquisition

Acquiring time data in low degree of detail of the process descriptions scribed state data, different approaches have been defined:

• Work sampling measures by using short-time observation [START_REF] Simons | Das Multimoment-Zeitmeßverfahren[END_REF]. The results can be aggregated and evaluated • Time studies enable worker. In contrast to work sampling Prior to the data acquisition, an area has to be selected. Useful criteria are the head count or the repetition frequency of the process ing time or rather the potential by gaining repetitive productivity improvements. observed area and processes determine the data acquisition method: Work samplings

Example of the worker activity and object hierarchy

The worker activities are clustered in groups and structured with a numerical logic. To identify the worker activities and to minimize the data acquisition ef worker activity has an individual number, which implies the main and sub group. The same logic structures the object hierarchy. As a result each unique worker state can be described with a combination of an activity and an object.

and Worker State Matrix

The combination of the worker activity and object hierarchy is a generic worker acti A plausibility check helps to reduce the potential amount of combinations. There are two reasons for an invalid activity/object combination:

Technical and logical inconsistency: E.g., it is not possible to screw a colleague. Definitive inconsistency: It is invalid to screw a section, because small parts like clamps are screwed on large parts.

It may be necessary to modify the matrix for the data acquisition, because the worker activities are universally valid and have to complement only in special cases.

the objects have to be adapted to the use case, but it is possible to use g industries. The tailored matrix is the input for the data acquisition.

cquisition

Acquiring time data in OKP is not common, because of the long operation degree of detail of the process descriptions. For the acquisition of above d different approaches have been defined: measures the frequency of occurrence of certain predefined events time observations at predetermined times in the investigation area ]. The results can be aggregated and evaluated statistically.

studies enable a detection of detailed work processes without interrupting the worker. In contrast to work sampling, time study maesure actual times. the data acquisition, an area has to be selected. Useful criteria are the head count or the repetition frequency of the process due to the large amount of paid wor ing time or rather the potential by gaining repetitive productivity improvements. observed area and processes determine the data acquisition method: Work samplings The worker activities are clustered in groups and structured with a numerical logic. To identify the worker activities and to minimize the data acquisition effort, each worker activity has an individual number, which implies the main and sub group. The same logic structures the object hierarchy. As a result each unique worker state can be is a generic worker activ-A plausibility check helps to reduce the potential amount of ect combination:

Technical and logical inconsistency: E.g., it is not possible to screw a colleague. Definitive inconsistency: It is invalid to screw a section, because small parts like matrix for the data acquisition, because the worker activities are universally valid and have to complement only in special cases.

case, but it is possible to use gered matrix is the input for the data acquisition.

times and above dethe frequency of occurrence of certain predefined events the investigation area a detection of detailed work processes without interrupting the the data acquisition, an area has to be selected. Useful criteria are the head the large amount of paid working time or rather the potential by gaining repetitive productivity improvements. The observed area and processes determine the data acquisition method: Work samplings are used in manual working time studies suit the construction site principle often. The above described and modified matrix defines the state categories.

To gain efficient productivity improvements be combined with a repetitive and generic working cycle.

Generic Working C

The aim of the generic working cycle is to enable repeatable improvements. As in mass production, repeti methods. From the perspective of the worker in an OKP environment the working process can be determined At the information phase the worker clarifies the work task and allocates all r quired information. The next the component preparation phase, the worker sets up machines and bui equipment. When everything is prepared, the worker can execute his work. This is t only value-adding activity tools back document results. fined as operational fields. These fields facilitate a goal tize improvement activities and support the deduction of standard methods.

To gain repetitive productivity improvements, the output from the data acquisition has to be aggregated to the described generic working cycle.

Data Aggregation

The paid working time worker absence consists mainly of times for vacation, training or illness. This info mation has to be gathered from orded with the defined worker state matrix. time is carried out manually and supported by two principles:

• The predefined worker activitie For example: reading is always in the • Ambiguous worker activities can be assigned to operation fields by considering the objects. For example: the combination of the worker ject engineering drawin with object drill this worker st

If each worker state is classified by these two guidel acquisition can be aggregated and assigned to the operation fields in manual working shops or productions cells with transparent overview; construction site principle with generic processes, which repeat he above described and modified matrix defines the state categories.

ient productivity improvements the result of the data acquisition be combined with a repetitive and generic working cycle.

Generic Working Cycle

The aim of the generic working cycle is to enable repeatable improvements. As in mass production, repetitions allow an efficient use of improvement activities and lean methods. From the perspective of the worker in an OKP environment the working process can be determined in five steps as shown in fig. 3:

Fig. 3. Generic Working Cycle

At the information phase the worker clarifies the work task and allocates all r quired information. The next step is to gather necessary materials and tools the component preparation phase, the worker sets up machines and builds auxiliary equipment. When everything is prepared, the worker can execute his work. This is t adding activity. At the end the worker has to clean the work area, bring results. The single phases of the generic working cyc fined as operational fields. These fields facilitate a goal-orientated approach to prior tize improvement activities and support the deduction of standard methods.

To gain repetitive productivity improvements, the output from the data acquisition has to be aggregated to the described generic working cycle.

Data Aggregation

The paid working time consist of different time portions (equation 1). The duration of worker absence consists mainly of times for vacation, training or illness. This info n has to be gathered from the corporate data system. The attendance can be re orded with the defined worker state matrix. The classification inside the attendance is carried out manually and supported by two principles:

The predefined worker activities have clear classifications specified in the matrix. For example: reading is always in the operation field Information. Ambiguous worker activities can be assigned to operation fields by considering the objects. For example: the combination of the worker activity searching and the o ject engineering drawings is part of the operation field Information; in combina object drill this worker state belongs to the operation field Material allocation.

If each worker state is classified by these two guidelines, the output from the data acquisition can be aggregated and assigned to the operation fields.

transparent overview; with generic processes, which repeat he above described and modified matrix defines the state categories.

he result of the data acquisition has to

The aim of the generic working cycle is to enable repeatable improvements. As in tions allow an efficient use of improvement activities and lean methods. From the perspective of the worker in an OKP environment the working At the information phase the worker clarifies the work task and allocates all retools. During lds auxiliary equipment. When everything is prepared, the worker can execute his work. This is the . At the end the worker has to clean the work area, bring The single phases of the generic working cycle are deorientated approach to priori-To gain repetitive productivity improvements, the output from the data acquisition

The duration of worker absence consists mainly of times for vacation, training or illness. This infor-

The attendance can be recinside the attendance s have clear classifications specified in the matrix.

Ambiguous worker activities can be assigned to operation fields by considering the activity searching and the obcombination d Material allocation. ines, the output from the data If time studies are used, the sum of the worker state durations per operation field plus a term for absence times and not recorded activities equals the paid working time. The work sampling method provides the ratio of worker states and can be converted to the paid time through multiplication with T paid (equation 2). The result of the data aggregation is a database of all worker states in the observed area. If required, it can be extended with additional information.

= + + (1)

Data Evaluation

The state data needs to be processed and illustrated using key figures and diagrams.

The evaluation allows to determine priorities and to deduct methods for operational fields. There are two ways of evaluation:

• Prioritization of the greatest operational field: The combination of worker activities with the greatest portion and most used objects facilitates the prioritization of productivity losses and references for a detailed root analysis. • Case-based improvement: If a process is recorded with the worker activities state matrix, it is possible to use this as a basis for a standard working description using the generic working cycle.

This key figures and diagrams allow to determine priorities, to derive improvement potentials and standardize work based on worker activity and object hierarchy.

Case Study

The proposed method was applied to an OKP at a shipyard. The worker state hierarchy was tailored on the basis of working plans and interviews. The final matrix included 62 different as well as 80 different objects. A plausibility check reduced the number of combinations to round about 1100 different worker states. Accordingly, the two data acquisition modes were assigned: Work sampling was done for the pre-outfitting and the outfitting at the berth; a time study was conducted at the prefabrication. A recording list with defined fields for activities, objects, time and notes was used and merged with a software tool.

The data acquisition required an effort of two eight hours for tailoring the worker activity and object hierarchy and preparation of the recording lists. The time study described a 3 hours working pr allocation of the operational fields for the working sample and the time study.

As expected the workers spent a big amount of their working time with preparative activities. The evaluation results are not representative, samples. However, the case study proves the functionality and practicability of the developed concept especially i the applicability of the worker activity and object hierarchy: Only four worker states out of 87 samples could not worker. All process steps could be described with the worker state matrix.

One challenge is to locate the worker at the at the outfitting. In 24% of the samples the worker was not detected in a time frame of one Minute. Also, the distance between the observation points is very long. This pro lem can be solved by using self reports or auxiliary utilities like location boards.

An evaluation with a significant amount of samples is planned to dem connection from allocation

Conclusion and Outlook

The paper has introduced a method for a state It combines worker activities and objects with operational fields of a generic working cycle to gain repetitive improvements. With the proposed method ers can improve transparency The case demonstrated the enhanced possibilities of a worker state matrix based on activities and objects. T different production types of OKP in a standardized way.

The ongoing studies at the IPMT include the definition of an accurate sample size for working samples. An improved software demonstrator for the data acquisition. In addition, a will be adapted for this methods

The data acquisition required an effort of two eight-hour days and additional eight hours for tailoring the worker activity and object hierarchy and preparation of the recording lists. The time study described a 3 hours working process. Fig. 4 allocation of the operational fields for the working sample and the time study. The evaluation results are not representative, due to of the small amount of samples. However, the case study proves the functionality and practicability of the especially in different types of production. The evaluation proved the applicability of the worker activity and object hierarchy: Only four worker states out of 87 samples could not be clearly identified and the observer had to ask the process steps could be described with the worker state matrix. One challenge is to locate the worker at the construction principle, which wa at the outfitting. In 24% of the samples the worker was not detected in a time frame of distance between the observation points is very long. This pro lem can be solved by using self reports or auxiliary utilities like location boards.

valuation with a significant amount of samples is planned to demonstrate the allocation of the operational fields to productivity potential.

Conclusion and Outlook

The paper has introduced a method for a state-oriented productivity analysis in OKP. It combines worker activities and objects with operational fields of a generic working o gain repetitive improvements. With the proposed method, production mana transparency of productivity potentials with low effort. The case demonstrated the enhanced possibilities of a worker state matrix based on activities and objects. This tool is suitable to describe the work process also in the different production types of OKP in a standardized way. The ongoing studies at the IPMT include the definition of an accurate sample size for working samples. An improved software demonstrator will further reduce the effort the data acquisition. In addition, another data acquisition method like self for this methods and evaluated.

dditional eight hours for tailoring the worker activity and object hierarchy and preparation of the shows the allocation of the operational fields for the working sample and the time study. the workers spent a big amount of their working time with preparative of the small amount of samples. However, the case study proves the functionality and practicability of the The evaluation proved the applicability of the worker activity and object hierarchy: Only four worker states clearly identified and the observer had to ask the construction principle, which was used at the outfitting. In 24% of the samples the worker was not detected in a time frame of distance between the observation points is very long. This problem can be solved by using self reports or auxiliary utilities like location boards.

onstrate the of the operational fields to productivity potential. oriented productivity analysis in OKP. It combines worker activities and objects with operational fields of a generic working production manag-

The case demonstrated the enhanced possibilities of a worker state matrix based on his tool is suitable to describe the work process also in the

The ongoing studies at the IPMT include the definition of an accurate sample size for will further reduce the effort data acquisition method like self-reports Furthermore, the evaluation has to be done with further industrial partners to cover different types of productions. A next research step will be to link the distribution of the operational fields with standard optimization. The case showed the high demand on adapted or new improvement methods for OKP especially in the operational fields gathering information and preparing the components and working place.

Fig. 4 .

 4 Fig. 4. Allocation to operational fields

Acknowledgement

The results presented in this paper were researched in the PROSPER project. It is founded by the German Government (Bundesministerium für Wirtschaft und Technologie -BMWi / Projektträger Jülich PTJ) due to a decision of the German Bundestag.


Simone Zanoni
email: zanoni@ing.unibs.it

Laura Mazzoldi
email: laura.mazzoldi@ing.unibs.it

Long term analysis of Energy Payback Time for PV Systems

Keywords: Energy payback, energy breakeven, PV systems

The energy payback performance of an energy generating technology such as PV, is usually based on a single system considering static parameters for its evaluation. However it is recognized that performances of an installed systems decrease over time, while, on the other hand, the performances of new systems is expected to slightly increase over time. Additionally the energy required for manufacturing a new system has decreased significantly in the last years and additional decrease is expected in the near future; moreover the opportunity to recycle materials from dismantled PV installations is becoming massively investigated and some technologies are already on industrial scale. These dynamic aspects inspired the present work that firstly consider the calculation of the energy payback of PV systems that should drive the most sustainable decision regarding the optimal timing for dismissing of an old PV system and replacement with a new one.

Introduction

Photovoltaic is a fast growing market: it has boomed over the last decade, and its expansion is expected to continue worldwide in 2011 about half of the previously cumulated PV module capacity entered the market. Energy Payback Time is defined as the period required for a (renewable) energy system to generate the same amount of energy (in terms of primary energy equivalent) that was consumed by the system itself during its life. New energy technologies are evaluated by this criteria in order to estimate their ability to contribute to our growing energy needs and to deal with carbon emissions problems [START_REF] Gutowski | Energy payback for energy systems ensembles during growth[END_REF]. However it should be noted that the Energy Payback Time of PV systems is dependent on the geographical location: PV systems in Northern Europe need around 4 years to balance the inherent energy, while PV systems in the South equal their energy input after 2 years and less. The environmental performance of PV systems was characterized in life cycle studies [START_REF] Raugei | Life cycle assessment and energy pay-back time of advanced photovoltaic modules: CdTe and CIS compared to poly-Si[END_REF]- [START_REF] Fthenakis | Emissions from photovoltaic life cycles[END_REF].

The energy performance of new technologies can and often does improve as the technology evolves.

In the last 10 years, the efficiency of average commercial wafer-based silicon modules increased from about 12% to 15%; moreover usage for silicon cells has been reduced significantly during the last 5 years from around 16 g/Wp to 6 g/Wp due to increased efficiencies and thinner wafers. Recycling activity extract from PV modules three primary recyclable materials: aluminium, glass and unrefined semiconductor material. The life cycle assessment of CdTe PV module recycling has been described in [START_REF] Held | Life Cycle Assessment of CdTe Module Recycling[END_REF]- [START_REF] Sinha | End-of-life cdte pv recycling with semiconductor refining[END_REF]. Many of these effects could affect the energy performance parameters. Therefore we will show that Energy Payback Time should be properly adjusted when considering an already installed system and the decision on dismantling and replace it with a new system.

Model

In the following, we develop a model that is the starting point for the development of a further analysis, which is aimed to determine when a PV system should be dismantled and/or substituted by a new one. Figure 1 presents a typical Energy Balance for a PV system, where the Energy Payback Time (EnPBT 1 ) and the Embodied Energy (E 1 E ) required to manufacture all the components included into the system are considered.

Fig. 1.Cumulative energy of a PV system installed at time t=0

At t=0 the PV system is installed, and the Embodied Energy (E 1 E ) required to manufacture all the components is taken into consideration. After installation, the system produces a certain amount of energy (namely the annual produced energy, E P,t ), which is a function of the total power installed (P), the efficiency (η t , for the t-th year after installation), and the annual number of equivalent hours of production, which is usually considered as a constant over time and it depends on the geographical location of the plant. After n years (t = EnPBT 1 ) the PV system starts to be energetically profitable, i.e. the cumulative energy assumes positive values after n years. Usually a PV system is considered operative until the end of its lifetime (LT), which is usually assumed to be 25 years. However the introduction of new technologies can lead to the decision of replacing the installed modules with new modules, on the same available space. Thus after t 1 years from its installation, plant #1 can be replaced by plant #2: the cumulative energy (CE t1 ) decreases dramatically, as the Embodied Energy for the production of the modules included in plant #2 (E 2 E ) must be summed up to the cumulative energy produced by #1 until t 1 . In Figure 2 it is assumed that E 2 E ≤ CE t1 , so that the total cumulative energy (CE t1 -E 2 E ) ≥ 0. After t' (t 1 ≤ t' ≤ t 2 ) from the first installation of #1, the expected cumulative energy related to plant #1, would be CE -100000 Starting from the considerations introduced in the first paragraphs, the Embodied Energy E 2 E required to manufacture the system #2 is lower than the energy required to produce system #1. The reason is that with the introduction of new technologies, the required production energy is lower, i.e. developing new processes that requires less semiconductor material. Thus the relationship of embodied energy of modules related to plant #1 and #2, is E 2 E ≤ E 1 E . Moreover Figure 2 shows that the curve representing the cumulative energy related to plant #2 has a greater slope the one related to plant #1: this is a consequence of the increased performances of system #2, that allow to install a greater power on the same area of plant #1. Therefore the respective relationship on Energy Payback Time for the new systems (EnPBT 2 ), with respect to the old one (EnPBT 1 ) becomes EnPBT 2 ≤ EnPBT 1 . It should be noted that those two Energy Payback Time are calculated with respect to the base case scenario of no previous system installed.

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In order to answer the first question "should the system installed at time t=0 be replaced by a new system after some years from its installation, from an energy point of view?" For 0 ≤ t ≤ TTEE 1-2 (where TTEE indicates the time to equivalent energy of system #1 and system #2) the cumulative energy produced by system #1 (effectively for t < t', theoretically for t' ≤ t < TTEE 1-2 ), represented by the black continuous line in Figure 3, is higher than the cumulative energy produced when substitution t = t' is im--1.000.000,00 -500.000,00 -500.000,00 1.000.000,00 1.500.000,00 2.000.000,00 2.500.000,00 3.000.000,00 0 10 20 30 40 50

#1 #2

#years Cumulative Energy (kWh)

TTEE 1-2 t 2 E 2 E t 1 CE t2 CE t1 CE 1 t CE 2 t
plemented (grey dashed line in Figure 3), while for t ≥ TTEE 1-2 the opposite situation arises.

In Figure 3 it is also highlighted the value of ReEnPBT t', (1-2) , which represents the Replacement Energy Payback Time of the plant #1 with plant #2, at time t': the next paragraph focuses the discussion on such a value, in order to determine whether or not it is convenient (from the energy point of view) to replace an existing system, or to install another one next to it.

Fig. 3.Replacement Energy Payback Time of PV system #2

Recalling the main considerations presented in the previous paragraph, such as the reduction in energy required for manufacturing a module, lead to a decrease in Energy Payback Time for the single plant. Thus, as reported in Figure 4, the Replacement Energy Payback Time is a decreasing function of the substitution time t'. Typically for three different substitution times, t' A , t' B and t' B , with t' A ≤ t' B ≤ t' B : ReEnPBT t'A ≥ReEnPBT t'B ≥ReEnPBT t'B ReEnPBT t',(

Numerical Analysis

To study the behaviour of the model presented in the previous section, a numerical analysis is performed to investigate how the model parameters influence the energy model. In table 1 main parameters considered as reference for the numerical analysis are reported. In case of replacement at the 15-th year (t = 15), the Replacement Energy Payback Time is 18.02 years. For the other two examined cases (replacement after 20 years, t=20, and 25 years, t=25), the Replacement Energy Payback Time is equal to 14.37 years and 12.02 years, respectively. Therefore for this case even after 25 years from the installation of the system #1 the Replacement Energy Payback Time ReEnPBT t', (1- 2) is larger than the new system Energy Payback Time (EnPBT 2 ) and thus it is not convenient to replace the old system with a new one but it is preferable to add a new system and keep operating the old one. Further analysis could be devoted to the determination of the replacement rime t ' .

Conclusion

The analysis presented here has never been considered by energy analysts, because, usually the attention is focused on a single system measures on a mid-term time basis and main energy basis considered parameters, such as, mainly, the energy payback time of a new installation. Due to the described growth in the number of PV installations in recent years we are convinced that also a long term analysis should be valuable, considering the option of replacing an old system after several years of production in favour of a new and most performing system. This work is the first attempt to depict the problem of the replacement decision on an energy basis considering most of the parameters that influence the problem. Next step of the work is the development of an analytical model so as to perform an analytical sensitivity analysis of the break even time from which it is convenient to replace the old installation. Moreover an economic analysis of the problem presented could be valuable, even if from this point of view the analysis is strongly affected by the country and year of the considered PV installation (due to differences in the incentive scheme and changes of that over time). Finally it should be noted that the analysis included here, if properly adjusted, could be applied to any kind of energy system from wind power to biomass or biogas systems.

Fig. 2 .

 2 Fig. 2. Cumulative energy of two PV systems (#1 installed at t=0 and #2 installed ad t=t 1 )

Fig. 4 .

 4 Fig. 4.Replacement Energy Payback Time of PV systems replaced at different timesSuch evidence suggests the existence of a replacement time value, t * , that represents the value under which the substitution of the plant modules is not profitable from an energy production point of view: the associated Replacement Energy Payback Time is greater than the Energy Payback Time of a new system. The model shows that for replacement time greater than t * the replacement of the PV system becomes profitable: the associated Replacement Energy Payback Time is lower than the Energy Payback Time of a new system.

  Gutowski et al.[START_REF] Gutowski | Energy payback for energy systems ensembles during growth[END_REF] studied performance of growing energy systems ensembles, identifying an optimum growth rate (largest value of net energy production) and critical growth rate (rate at which the ensemble generates no new energy). A case study on PV ensembles is presented and discussed. Another important aspect for the long-term sustainability of the PV industry is the end-of-life photovoltaic (PV) module recycling, considering the large future expected waste volumes. As indicated by the inclusion of photovoltaic (PV) in the European Union Directive on Waste Electrical and Electronic Equipment (WEEE), end-of-life module recycling is important to the long-term sustainability of the PV industry. In addition, in order to help the management of large future expected waste volumes[START_REF] Sander | Study on the Development of a Take Back and Recovery System for Photovoltaic Products[END_REF], PV recycling can contribute to resource efficiency by preserving valuable raw materials (glass, copper, aluminium, semiconductor materials, etc.) for future use in PV modules or other new products.

Table 1 .

 1 PV System parameters considered

	Available area	400 m 2
	First installation year	2012
	PV modules technology	Si poly-crystalline