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The Working Environment in LCA

3 Application of the method

3.1 Inventory
      3.1.1 Inventory procedure
      3.1.2 Matching the inventory and the database
3.2 Impact assessment
      3.2.1 Normalisation
      3.2.2 Weighting
3.3 Interpretation
      3.3.1 Interpretation following inventory
      3.3.2 Interpretation after normalisation
3.4 The method applied on a case
      3.4.1 Making a flowchart
      3.4.2 Aggregation from the component list
      3.4.3 Energy and transportation
      3.4.4 Matching the aggregated information with the database
      3.4.5 The calculations
      3.4.6 Creating a better overview
      3.4.7 Creating the graphic overview
      3.4.8 Normalisation

The method has been developed with the purpose of including the working environment in LCA. One of the main goals of LCA is generally to give an overview of the main impacts in the life cycle of a product, for example in product development. A LCA of the working environment that is based on sector assessments can meet this general goal because it gives an indication of where in the life cycle the main impacts can be expected and how big they are.

The process of making an LCA with inclusion of the working environment does not differ from a ”normal” LCA. The main difference is that important indicators for working environmental impacts are included, giving the possibility for an assessment of whether the results of changes in material composition and applied processes also causes significant changes in the overall impacts.

3.1 Inventory

The method has been developed with the aim of being integrated in the overall EDIP-method and eventually also being a part of the EDIP PC-tool. The PC-tool can however not handle the changes in data format and impact assessment that are the consequence of the new method. It is recommended that the changes be implemented when revising the current version of the PC-tool. This will cause the working environment to be a naturally integrated part of the overall assessment.

Until a PC-tool can handle the database it is recommended that a working environmental LCA should be performed separately, using a spreadsheet. A spreadsheet in EXCEL-format containing the database can be downloaded from the web-site of LCA Center (www.lca-center.dk/cms/site.asp?p=2217). A procedure for use of this spreadsheet is outlined in the following paragraphs and exemplified in section 3.4. It should be noticed that the outlined procedure is only a suggestion and that other practitioners may choose to handle the data by another procedure. This will not be detrimental to the precision and reliability as long as the procedure and the limitations of the database is described in a transparent way.

3.1.1 Inventory procedure

1. The first step is to calculate the materials flows for the product. The most precise calculations are obtained by using the EDIP PC-tool or another LCA-program and use the results directly for further calculations of the working environmental impacts. The advantage of using a dedicated PC-program is that material flows from previous and unseen activities in the life cycle will be automatically included.
   
   Another, but less precise procedure is to use the component list for the product for calculation of in-going material flows (see e.g. Table 4). If this procedure is used, the practitioner will have to make special considerations regarding the activities earlier in the life cycle. As an example, the material  input for production of one kilo of primary plastics - generally speaking - is one kilo of crude oil and one kilo of natural gas. These inputs must be accounted for. The primary plastic is subsequently processed, and here there are several processes to choose from in the database – see step 2. The material loss in these processes is however relatively small and can often be neglected. In the case described in section 3.4 the component list is used for the calculations together with a supplementary calculation of the amount of energy resources that enters the life cycle.
2. The materials flows calculated in the first step are now distributed (aggregated) on relevant processes in the developed database (see the example in Table 7, section 3.4). Before this can be done it is therefore necessary to establish a good overview of all the processes in the database. As an example, the weight of all iron- and steel components are added in order to calculate the impacts from production of the basic raw materials (“Danish iron- and steelworks” in the database). In order to calculate the impacts from the following manufacturing processes, the weight of the components is distributed on relevant processes. In the case described in section 3.4, the basic iron and steel is processed in two different sectors, i.e. “Production of screws, springs, etc.” and “Productions of other metal products”. Another example is that the database contains information on nine different types of plastic processing, two of which are relevant in the case. The results of the second step is that a more operational overview is established, i.e. the number of material and process combinations has been reduced significantly.
3. The aggregated material flows from step 2 are now entered into a spreadsheet. This can for example be done by entering information on each process regarding material, process name, NACE-code and weight in four columns.
4. For each process the weight is multiplied with the impacts per weight unit for each of the effect categories. In practice this can be done in many ways, e.g. by adding ten columns with the same headings as in the developed database. In each of the cells in the ten columns, a formula of the type “= A*B” is entered, where “A” refers to the address of the cell containing information on the weight of the material and “B” refers to the address of the cell in the database that contains information on the impact per weight unit for the relevant effect category and process.
5. When the formulas have been entered the spreadsheet automatically per forms the calculations. The resulting figures can subsequently be added in order to calculate the total impacts in each effect category. It is also possible to make further groupings/aggregations of the processes and thereby create other and perhaps more operational overviews. In the case in section 3.4 it was chosen to add the life cycle impacts relating to components made from different materials (plastic, steel, paper/cardboard, etc.) in order to compare these to each other and to other activities like assembling, transportation and production of energy resources. It is also possible to add the impacts from processes in different phases in the life cycle, e.g. by adding the impacts from different types of raw material production, material processing, assembly and transportation, respectively.
6. It is not possible to give a more precise description of the options that are available, simply because each case has its own characteristics with respect to goal and scope of the LCA as well as the material composition and the life cycle of the product(s) under examination. The case in section 3.4 can be used for inspiration, but the database is in principle open for all types of calculations and associated interpretations.

3.1.2 Matching the inventory and the database

When developing the database the aim was to find information for as many typical ”LCA-activities” as possible. However, one of the largest uncertainties in the calculation procedure is probably to find data sets in the database that matches the actual activities.

This problem is caused by the fact that many thousand product groups have to be related to a relatively small number of sectors, less than 300. In the project, Statistics Denmark who has the copyright to the information did this. In practice, the procedure implies that many processes are described by the same set of data although they are significantly different. One example is that the sector ”Production of plastic packaging” uses thermoforming, injection moulding, blow moulding, extrusion, foaming, etc. of all types of plastic.

For other types of processes a single set of data is used to describe a complicated process sequence. An example is ”Production of household appliances” which generally is done in an assembly line and involves a number of persons. The data format for such processes is the same as for other processes; i.e. the impacts are given per produced unit of weight .This means that for a household appliance weighing 5 kilo, the impacts in the database must be multiplied with 0.005 (the database figures are per ton) in order to calculate the impacts per appliance for the assembly process.

Another uncertainty is that it is not possible to take the impacts from previous processes into consideration unless they are specified. This is for example the case for production of energy resources; e.g. the impacts from production of household appliances only include the production itself and not the production of the energy used in the production. When using a spreadsheet for the calculations, it is not possible to make the iterations that are an integrated part of the EDIP PC-tool. Both types of uncertainties are judged to be of minor importance, but may be avoided if the database is integrated in the PC-tool.

3.2 Impact assessment

When the inventory data have been calculated it is not necessary to process them further in order to make an impact assessment. The reason for this is that the inventory is measured in category endpoint in the cause-effect chain. The potential effects are in other words measured directly in the inventory.

The working environmental impacts differ in this respect from most other impact categories, where the potential impacts are measured much earlier in the cause-effect chain. As an example, the category endpoint for global warming is regional changes in temperature and their associated socioeconomic effects following desertification or increased water levels. These effects cannot be measured directly, and instead the impact assessment is performed in two steps. Firstly, emissions are classified as contributing to global warming (e.g. CO² and CH⁴) and secondly their contribution is calculated by multiplying with their potential for causing the effect, e.g. by taking their specific ability to absorb IR-light and their residence time in the atmosphere.

3.2.1 Normalisation

The aim of the normalisation step in EDIP is to give an overview of the relative importance of the single effect categories. This is done by relating the actual (calculated) impact to the average impact caused by a person in the relevant geographic area. Hereby, the normalisation step becomes similar to that used in other impact categories in EDIP.

In the present methodology, the basis for the normalisation is easily identified as the total number of reported working environmental accidents and damages in Denmark, distributed evenly on the number of Danes in the same period of time. As for the other calculations, the normalisation factors in Table 3 have been calculated as a three-year average for 1995-1997.

The procedure is thus simple, using the total number of accidents and work-related diseases as reported to the Danish Labour Inspectorate and dividing with the number of inhabitants in Denmark.

The normalisation reference or person equivalent can be interpreted in the way that if every Dane was working, one out of a hundred persons would experience an accident at work every year.

Table 3. Normalisation factors for working environmental impacts

The normalisation reference for the working environment is comparable to the normalisation reference for other environmental impacts, e.g. the contribution of an average Dane to acidification is calculated by dividing the total Danish contribution to acidification with the number of inhabitants in Denmark.

When performing the normalisation step, i.e. using the person equivalent, it is possible to examine both how the working environment differs between products and how important the working environment is in comparison with the impacts in the natural environment.

In Table 3, another set of normalisation factors, “The worker equivalents”, is found. This set of figures show the probability for an average worker of experiencing an accident or report a work-related disease in a year. The only difference between the two sets of factors is that the worker equivalent is calculated using the number of employed persons in Denmark. The worker equivalent is suggested for use in specific working environmental LCAs, where absolute figures may give more suitable information than when using the Danish population as the normalisation reference. It should however be stressed that when the worker equivalent is used in normalisation, comparisons with other effect categories can not be made.

3.2.2 Weighting

The normalisation procedure for the working environment gives information on which effects that will be most frequently observed in the life cycle of a product. However, the most frequently observed effects are not necessarily the most problematic, e.g. fatal accidents must be regarded as more serious than hearing damages.

To account for this, the general EDIP methodology introduces an optional impact assessment step, namely weighting. The weighting of the impacts in the natural environment is done by using political targets for reduction in emissions.

This is however only possible to a limited degree for the working environment, as the only specified target is that the number of fatal accidents shall be reduced to zero before year 2005. In addition, the Danish minister of labour has identified a number of other impacts that are of special concern and therefore should be reduced or totally avoided by year 2005:

• Hearing damages
• Occupational exposure to carcinogenic substances and work-related damages to the central nervous system caused by exposure to solvents or heavy metals
• Injuries to children and adolescents at work
• Damages to health caused by psycho-social risk factors at work
• Sickness or serious annoyances caused by an unsatisfactory indoor climate
• Damages and injuries caused by lifting of heavy burdens or by monotonous repeated work
  

No specific goals have been specified for these impacts and it is also not possible to relate all the concerned impacts to the effect categories used in the methodology.

It is therefore suggested to exclude the weighting step from the assessment of working environmental impacts for the moment being. As a consequence, when comparing impacts in the natural environment to impacts in the working environment, this should be done following the normalisation step.

In the end, it is the judgement of the LCA-practitioner whether the results following normalisation are suitable for decision support or a supplementary interpretation of the results is necessary to compensate for the lack of weighting in the method. On the longer term, weighting methods using economic indicators can be developed and used to assess the relative seriousness of the single impacts. A possible database for this is information from the worker compensation board or workers experience insurance companies, where a price or value is attached to the many types of injuries and damages that may occur. It should be remarked that this type of weighting is not comparable to the general weighting method in EDIP.

3.3 Interpretation

The method has so far only been tested on a single case and it is therefore difficult to give precise guidelines as to how the results can be interpreted. The primary recommendation is to use information from both the basic inventory/impact assessment and the subsequent normalisation in the interpretation.

3.3.1 Interpretation following inventory

Following the inventory/impact assessment it is possible to establish an  overview of how much each of the activities contributes to the single effect categories. This can for example be illustrated in a bar diagram, summing the activities up to 100%.

At the same level it can also be illustrated how many accidents and injuries a product causes, measured in absolute numbers. The unit for this information is accidents/injuries per functional unit. A three-dimensional matrix (combining the absolute number of accidents and injuries with each life cycle phase and each effect category) can create the full overview, but in practice, a two-dimensional illustration is more operational.

3.3.2 Interpretation after normalisation

Following the normalisation it can be assessed which effect categories that are the most important in the life cycle of a product. This can for example be evidenced by using a diagram depicting the normalised values, measured in person equivalents and summed up for the whole life cycle. In this way the fact that some types of accidents and injuries are reported more frequently than others can be taken into account.

The interpretation of this kind of results is independent of the choice of person equivalents or worker equivalents as the normalisation base. It is however recommended to use person equivalents if comparison with other impact categories is performed.

The normalised values can also be used for another type of interpretation. By dividing the worker equivalent with the impact from a product or a functional unit it is calculated, how many products can be produced (or functional units fulfilled) before the average impact of a worker is reached. In this case the worker equivalent is used for the calculations because it gives more meaningful numbers.

The recommendations outlined above are illustrated in a case in the following sections.

3.4 The method applied on a case

The chosen case – an office chair – has also been used in other parts of the LCA-method development and consensus project. One of the reasons for choosing this case is that large parts of a LCA has already been performed, e.g. much of the necessary information was available also for the working environmental part of the LCA. No further data collection was performed in the present project.

3.4.1 Making a flowchart

The starting point for the LCA is a component list for the product with information on material type, weight and applied processes (e.g. surface treated or injection moulded). In order to create a better overview of the 

  comprehensive list of components, it is suggested as a first step that a flowchart for the generic material types (plastics, steel, metals, paper, etc.) is established.

The flowchart for the office chair is shown in Figure 1. The shaded boxes show the activities that could not be included in the calculations because of missing information. This is for example the case for forestry and surface treatment because the developed database does not contain data on these processes. Extraction of energy for transportation is also not included because the actual consumption was not calculated in the basic information for the study.

Figure 1. Flow chart for the ofice chair

3.4.2 Aggregation from the component list

The component list gives information on the amount of materials used in the product. Table 4 shows an excerpt from the component list for the office chair.

Table 4. Excerpt from the component list for the office chair

The office chair is made from more than 180 components that can be aggregated with respect to the basic material type and the weight (Table 5).

* Not included in the calculations

Table 5. Material content in the office chair

The data in Table 5 are used as input for the calculations of the impacts. The main aggregation is that different types of steel and plastics are found under two headings, steel and plastics, as it is not possible to make further discrimination in the database.

In the calculations it is assumed that the seat and back of the office chair will be replaced three times in the lifetime of the chair. The additional consumption of materials for this is included in the above figures.

3.4.3 Energy and transportation

The impacts from production of energy raw materials and transportation are also included in the assessment.

The overall consumption of oil, gas and coal for energy production and material feedstock has been used for the calculation, as no detailed information for the single materials was available. Production of electricity is only considered for the assembly process at the producers, as this was the only process for which this information was available.

For transportation, only national transportation in Denmark is considered and it is assumed that all transportation is performed by truck.

Transportation between earlier parts of the supply chain is not considered, but the extra transportation associated with replacement of seats and backs of the chair is included in the calculations.

The aggregated figures for consumption of energy raw materials and transportation are shown in Table 6.

Table 6. Energy and transportation data

3.4.4 Matching the aggregated information with the database

An integrated part of aggregating the data in the component list is to find sectors in the database, for which the activities match those in the life cycle. Table 7 shows the sectors that were chosen to match the activities in the life cycle of the office chair.  

* Not included in the calculations

Table 7. Sectors included in the calculations

Production of bronze is not included in the calculations because no sector in the database matches this activity directly. The potential error in this omission is however very small as the amount of bronze in the office chair is almost negligible. If an increased level of detail is requested, bronze could be included by using other processes, e.g. a combination of production of copper and production of lead, zinc and tin.

For steel and plastics, a number of sectors have been used to describe the life cycle, thereby giving the possibility for a more detailed assessment. For plastics, the life cycle starts with extraction of oil and natural gas, followed by production of basic plastics and ending with production of plastic packaging and production of other plastic products. For steel, the life cycle starts with production of steel and subsequently a division into production of screws and production of other steel products.

3.4.5 The calculations

The next step in the procedure is to multiply the information in Table 7 with the impacts per ton material that can be found in the database. It is important to observe that the units must match each other, e.g. weight is stated in tons.

  The calculations can most easily be performed in a spreadsheet. About 60 unit processes contribute to one or more impacts in the life cycle of an office chair. In the spreadsheet it is possible to see exactly how many accidents and damages each process causes and it is also simple to add the impacts to get an overview of the total impacts.

3.4.6 Creating a better overview

In order to create a better overview of the importance of each material or component it is suggested that the information is aggregated in the same way as was done with respect to the information is the component list, i.e. on the material level.

As an example all processes involved in the production of plastic components are aggregated, the exception being extraction of oil and natural gas that is aggregated under the heading energy production. The same can be done for other materials and process where appropriate, and the simplified overview can be presented in a new spreadsheet that gives better possibilities for a graphic presentation. This size of the new spreadsheet for the office chair is indicated in Table 8, where the number of processes has been reduced from about 50 to 14.

Click here to see the Table.

Table 8. An example of a spreadsheet with aggregated information

3.4.7 Creating the graphic overview

It is relatively simple to use the aggregated information in Table 8 for a graphic presentation of the results, provided the practitioner has some general experience with spreadsheet management. A number of possibilities are available and some of these are demonstrated in the following figures.

The first suggestion is to make a figure that illustrates the relative contribution from materials/processes to the total impacts from the product –the expected accidents and damages. This overview is presented for the office chair in Figure 2.

Figure 2. The relative contribution of materials and processes to the overall impacts from the office chair

As can be seen from Figure 2, the assembly process is the most important process for many of the impact categories considered by the method. However, both plastics and steel also have a large impact in some categories, e.g. plastics as a whole causes more airways diseases than the assembly process and steel production together.

It can also be seen from the figure that transportation only has a significant contribution to one impact category, accounting for about 10% of the expected fatal accidents. For all other impact categories, transportation contributes only with an insignificant part. For energy production, the contribution cannot be observed in the illustration. It should, however, be remembered that the database for production of electricity, especially extraction of coal, is of a poor quality.

Looking at the absolute contribution to the single impacts from each of the materials and processes can create another type of overview. An example is shown in Figure 3, where the number of expected accidents per million office chairs is allocated to each of the materials and processes. This overview is often valuable, as the database for accidents is the most complete, i.e. this information has been collected for all processes.

  It can be seen from the figure that the assembly process is the most important process with respect to the risk of accidents. It can also be seen that steel is more important than plastics. This is not the case for other impact categories as indicated in Figure 2.

Figure 3. The contribution of single materials to the overall number of accidents in the life cycle of an office chair

The materials rubber, glue and grease only account for a minor contribution, primarily because of their low weight. Energy production and transportation is also of minor importance.

3.4.8 Normalisation

The results from the impact assessment can subsequently be normalised in order to gain knowledge on which effects that is most affected by the activities in the life cycle of a product. The normalisation is done by relating the expected number of accidents and damages to the average reporting frequency for an average Danish citizen. In practice, this is done by dividing the number of accidents and damages from the product with the normalisation references given in Table 3. With this calculation, the impacts can be stated in person equivalents, i.e. the same unit that is used for other impact categories in the EDIP method (1 person equivalent = 1 PE = 1000 milli person equivalents = 1000 mPE). 

  Figure 4 shows the normalised impacts from the office chair. It can be seen that the life cycle activities has the most significant effect on CNS-function damage, with an impact that amounts to about twice as much as the other impact categories.

Figure 4. Normalised effects potential for the office chair

The effect potential measured in milli-person equivalents is an expression of how large a part of the annual impact on an average citizen that is caused by the production of an office chair. With respect to CNS-function damage only 25 chairs can be produced before the average impact is reached, while for skin diseases, 77 chairs can be produced.

The normalised results can be further detailed in the same way as was done in the impact assessment. In Figure 5 is shown how the single activities contribute to the expected accidents. It can be seen that the average annual impact from accidents in the assembly process is reached when each worker has assembled about 170 chairs. With respect to the steel used in the chair, the average annual impact is reached when steel for 370 chairs has been produced and processed into components.

Figure 5. Normalised values for accidents in the life cycle of the office chair

The results emerging from each step in the impact assessment are open for a more detailed assessment and interpretation. For each of the materials used in the product it is thus possible to distribute the impacts on the processes in the life cycle, normally 2-4 processes for each material. In doing so, a more precise assessment of where the largest impacts can be found is obtained. This increase in the level of detail can easily be achieved with the established inventory and may be a better basis for a dialogue between suppliers and producers about how to improve the working environment. In the case of the office chair an obvious choice will be to emphasise the need to avoid organic solvents, as these are a well-known cause of the dominating effect, CNS-function disorder.

Another possibility is to compare the results from an assessment of two different products, e.g. two office chairs. This type of comparison has not been performed in the current project, as only information on one office chair was available.

A third possibility is to compare the results from the working environmental LCA with the results from the other impact categories. With such a comparison the most obvious goal of including the working environment can be reached, i.e. that it is possible to see whether changes in choice of materials, components or manufacturing processes lead to an (unwanted) change in the working environmental impacts. This comparison with several types of effect categories has not been performed in the present study, as the results from the assessment of the impacts on the natural environment or resource consumption are not known.

The method provides new possibilities to integrate the working environment into LCA. It is, however, emphasized that it is often the conditions at and prioritisations of the single companies that is determining for the prevalence og working-related injuries. A company that has a certified management system for the working environment (e.g. OHSAS 18001) is able to document efforts that go beyond regulatory demands. By choosing such a supplier it is ensured that their working environment is the best possible within the given sector and that there is a possibility for improvement through dialogue.

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Version 1.0 December 2004, © Danish Environmental Protection Agency