Carrying out a simplified LCA implies the following:
Figure 1 - Representation of the aspects to take into account
Step 1 - Set objectives
Setting the objectives of the LCA is key, as it determines the level of detail needed to serve the purpose. The general objective is to compare different PSS scenarios that have the same end purpose, and to assist in the definition of the best options. As an indication and/or example, the goal is not to provide LCA data for Environmental Product Declaration (EPD), nor to provide data with a high level of precision.
Step 2 - Identify the company’s priorities and/or sector specific issues with regards to sustainable development
The identification of the company’s priorities and its stakeholder’s priorities enables to identify the relevant impacts that will be calculated during the LCA (e.g.: acidification, emission of greenhouse gases, etc.).
As an example, taking into account energy consumption in a market where energy costs are very high might be a priority.
Step 3 - Define the relevant steps in the PSS to be taken into account in the LCA
The simplified LCA focuses on the most relevant steps for each PSS, with regards to sustainable development. You should select the relevant steps of each PSS scenario in order to cover between 60-80 % of the selected impacts. The steps considered are often different for each impact.
The quickest way to do this is to call on sectorial / LCA experts, who will be able to pinpoint the relevant steps rapidly, and to use a mass cut off criteria of 60 to 80 %.
Otherwise, you can seek for existing LCA information, which will provide an idea of the relevant steps to consider.
For instance, considering the distribution of mineral water with glass bottles, the phases that are relevant with regards to their environmental impacts are:
- Effluents from the washing of re-used bottles (water pollution);
- Transport of the filled bottles from the producer to the distributor (energy and greenhouse gases);
- Regeneration for reuse or recycling of the water bottles (energy and waste);
- Energy use for on-site production of the bottles.
This implies that a number of steps can be neglected for the simplified LCA: label production, sticking of the labels, energy needed for storage of the water bottles, impacts of the production of the bottle’s cap, transport from the supermarket to the consumer’s home.
Step 4 - Define the flows that will enable to calculate the selected impacts
Once you have identified the relevant steps, you need to identify a selection of flows that will enable to cover approximately 60-80 % of the impacts you have selected.
For instance, in the case of the impact ‘emission of greenhouse gases’, you can identify one or a few of the gases that contributes the most to the emission of greenhouse gases. In the case of a landfill, it would be methane, whereas is the case of a combustion process, it would be carbon dioxide.
Step 5 - Gather data on the selected flows to calculate impacts
Once the list of selected flows has been drawn, you have to collect relevant data for each of the steps identified, for each PSS scenario considered. You should collect data that is readily available: company data or existing LCA data on that sector.
Since the level of detail sought in a simplified LCA is not as high as for a full LCA, you can make use of models to estimate the flows, or make use of data on averages, or make extrapolations.
Step 6 - Calculate the impacts for each PSS scenario and compare the results
The calculation of the impacts should be achieved using standardised methods of calculation (these methods already exists and have been compiled in the LCA software TEAM).
The analysis of the difference in impact between the PSS scenarios should focus only on differences by a factor of 4 or 10. Indeed, considering the aim of the simplified LCA and the level of uncertainty that is higher than for full LCAs, it would not make sense to focus on small differences, as illustrated below:
Figure 2 - Impact of the margins of uncertainties on the interpretation of results
It is recommended to carry out an estimation of the uncertainties in your LCA in order to decide what is the relevant order of magnitude of differences to be considered.
One scenario might be better with regards to one impact but worse than another scenario with regards to another impact (e.g.: scenario minimising GHG emissions but generating more waste).
Step 7 - Establish conclusions
The last step is to draw conclusions on the analysis carried out. The conclusions should be formulated so as to help the development process of the PSS:
- Which scenario seems to have the less overall environmental impact?
- What are the key aspects / steps of the PSS that should be optimised during the design phases so as to make the PSS more sustainable?
Should some incoherencies be found, further data collection can be carried out and an iterative process achieved.