A full lifecycle assessment (LCA) is the most comprehensive and also most commonly accepted way of determining the impact of a product or service.
Depending on the complexity of the assessed product and its supply chain, the assessment can become an extensive activity. To reduce the resource intensity of an LCA, average values are often used, for example for the carbon emissions per kilometer from a 40-tonne diesel lorry or the use of a unit of main grid electricity. However, the more average values are used, the less exact and specific an LCA becomes.
An LCA consists of four steps. First, the scope of the assessment needs to be defined: what function, system or product is to be assessed; the definition of a functional unit; assumptions; and, importantly, the boundaries. The assessment is an iterative process and boundaries may be adjusted through- out the exercise. Nevertheless, standards like PAS 2050 now determine boundaries for the assessment. Although LCAs were initially developed for environmental emissions, and in particular greenhouse gases, the principle can be applied to any impact that a supply chain may cause.
Sustainable Purchasing and Procurement 171 Examples of a functional unit can be the emissions ‘per visit’ for a service, per kilogram of a product, the usual lifetime of product (for example energy savings from the improved energy efficiency of an electrical item), or per driven kilometer.
Second, within the boundaries, all input is recorded and assessed in an inventory analysis which forms the basis of the assessment. Collecting data hereby is often a more complicated task than initially anticipated and trans- ferring input into functional units needs some consideration.
Third, following the analysis of the input side, all emissions are evalu- ated in an impact assessment. This is connected to the inventory data; all inventory data is put into impact categories and then processed within each category. As a result, the contributors to a particular impact can be grouped together. They can have different weightings, depending on their impact;
for example, within the group of greenhouse gases that contribute to global warming, some have worse effects than others and therefore need to be factored differently.
In the last step, the interpretation, the results from inventory analysis and impact assessment are connected to gain knowledge about the environ- mental impact of the assessed product and to make recommendations on improvements (BSI, 2011).
As thorough LCAs have the potential to require significant resources, different levels of detail and sophistication have evolved. The most accurate investigation can be found in a detailed LCA, where all parts are evaluated in detail individually. This requires expert knowledge about the processes and emissions occurring at the individual stages of the supply chain. It also differentiates between global impact and regional impact. The major disad- vantage of the detailed LCA is the effort that is needed to assess the supply chain to such a level of detail. Therefore, more simplified methods – concep- tual LCA and simplified or streamlined LCA – evolved. The conceptual LCA is positioned at the opposite extreme to the detailed assessment. It qualita- tively examines what factors and areas in the lifecycle need to be focused on and then only assesses those. This can, however, only be used as guidance for management, as the limited scope does not comply with the ISO standards for an LCA.
The streamlined LCA is placed in between these two approaches. It allows a comprehensive assessment, but rather uses generic data and does not meas- ure each aspect individually. Therefore, it contains all relevant aspects but does not require the effort of a detailed LCA. Using generic data, however, means the assessment loses accuracy. Simplification can also be achieved through a screening stage in which insignificant emission contributors are
identified and then do not need to be assessed in the analysis. Through this process, the LCA focuses on the key contributors, where the most environ- mental improvement potential lies (BSI, 2011).
The definition of the boundaries for an LCA crucially influences the overall result and environmental performance of a product. The most comprehensive guidelines and definitions for boundaries of LCAs exist in the area of greenhouse gases and carbon footprints. Standardized guide- lines limit deviation in the assessment activity and simplify carbon footprint evaluations. PAS 2050 is currently the most commonly applied standard for carbon footprinting. For example, it provides a threshold so that inputs in the inventory analysis can only be deemed insignificant if they contribute less than 1 per cent of the lifecycle greenhouse gas emissions of a product.
When assessing greenhouse gas emissions, the time dimension of the greenhouse gases’ impact influences the results. A range of greenhouse gases exists and their impact can be more short term or long term after they are released. Depending on the chosen time horizon, the impact of greenhouse gases such as CO2 equivalents changes. The PAS 2050 standard sets 100 years as the time horizon for the impact of emitted greenhouse gases, which needs to be included in the lifecycle assessment. It also specifies how carbon storage is allowed to be considered and that land use changes are included for the first 20 years (Sinden, 2009).
The significance of system boundaries is shown in a study on the carbon footprint of office paper. The study applies three approaches: ISO 14040/14044, PAS 2050 and the framework by the Confederation of European Paper Industries (CEPI). Unsurprisingly, the industry’s frame- work considers the least number of materials in its system boundary and the PAS 2050 standard still included significantly more materials than the ISO standards. In the assessment using the CEPI framework, only 90 per cent of greenhouse gas emissions were accounted for. Cut-off rules were compara- tively narrow; for example, in transportation using the CEPI framework only the journey to the distribution platform is taken into consideration. The ISO 14040/14044 standards considered 98 per cent of greenhouse gas emis- sions compared to the assessment using the PAS 2050 standard. However, they also required significantly less effort in the data collection. The study allocated carbon footprints per tonne of office paper of 860 (CEPI), 930 (ISO 14040/14044) and 950 kgCO2e (PAS 2050). However, when it comes to labelling products with a carbon footprint, the functional unit of a ‘sheet of A4 paper’ might be more accurate, as produced sheets can be of differ- ent weight categories depending on their thickness and density (Dias and Arroja, 2012).
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