Table of Contents:
Quantification of the CFP
As illustrated by the Table Al and Figures Al and A2 in the Annex, the GHG-statement should be aligned with the needs and requirements of the intended user of the statement. As for an EPD, the quantification and communication should be conducted according to the requirements in the PCR. The methodology for a CFP follows the same 4 steps as for an LCA.
CFP goals and scope
For a CFP. the overall goal is to calculate the potential contribution of a product to global warming expressed as CO,-equivalents. In defining the scope of the CFP study, the system under study, the subsystems and the system elements, the system boundaries, its functional unit, data and data quality requirements should be described. The system boundary shall be the basis used to determine which unit processes contribute to the CFP study. As for EPDs. a product flow diagram, including system elements and an overview of the life cycle stages of the product as shown under the LC-Inventory (LCI), is helpful. For large products, such diagrams can be quite complex and they will vary according to the type of product.
In addition to a diagram, the full documentation of each part of the life cycle that is likely to contribute to GHG-emissions should be undertaken. This can include GHG-emissions during raw material extraction, which often spans several locations worldwide; the manufacture of the product, including transport between production sites and to the retailer and user; and the transportation and energy used during the eud-of-life treatment. Different scenarios might be a part of the analyses.
Depending on the type of product, the use-phase can be quite unpredictable. For products that consume ener gy, it is important that this is described in a consistent way. Similarly, an overview of eud- of-life processes should be included, e.g., collection, packaging and transport, preparation for recycling and reuse, dismantling of components, shredding and sorting material for recycling, energy recovery or incineration.
CFP inventory analysis
During the LCI, the collected data (measured, calculated or estimated), shall be used to quantify the inputs and outputs of unit processes for each system element. The CFP study shall include an identification of actual processes shared with other product systems and deal with them in accordance with relevant allocation procedures.
CFP impact assessment
Figure 2 illustrates a model for impact assessment. According to the ISO 14067-standard (ISO, 2018c), the impact of each GHG-emissions shall be calculated by multiplying the mass of GHG released or removed by the 100-year Global Warming Potential (GWP 100) given by the International Panel for Climate Change (IPCC) in units of kg CO,-equivalents per kg emission (Mhyer et al., 2013). The CFP is the sum of the calculated impacts.
According to the IPCC, the 100-year global warming potential (GWP) is used to represent shorter- term impacts of climate change, reflecting the rate of wanning. 100-year global temperature potential (GTP 100) is used as an indicator for the longer-term impacts of climate change, reflecting the long-term temperature rise. There is no scientific basis for choosing a 100-year tune horizon compared to other time horizons, but the time horizon is a value judgement of an international convention that weighs the effects that are likely to occur over different time horizons (Mhyer et ah, 2013). Furthermore, ISO 14067:2018 (ISO, 2018c) recommends how to calculate and assess, e.g., the impact of removals of CO, into biomass or emissions of biogenic CO,. Similarly, the standard recommends that the most recent IPCC report be used to set the characterisation factors for fossil and biogenic methane.
The final stage, the interpretation of a CFP study, should include an identification of the significant issues regarding the life cycle stages, unit processes, subsystems and flows based on the results of the quantification of the CFP. According to ISO 14026 (ISO, 2017a), the results should be presented in a CFP study report and be further used in footprint communications. The CFP study report shall include information about the system boundary, including the type of inputs and outputs of the system as elementaiy flows, considering then importance for the conclusions of the CFP study. The results shall be documented in mass of CO,-equivalents per functional unit as specified in the PCR. The results of the quantification of the CFP shall be further interpreted according to the defined goal and scope of the CFP study.
Case Study—Galvanised Steel Staircase
This case study considers the carbon foot printing of a Steel staircase, see Figure 3, manufactured in Norway, using LCA methodology. The material flow diagram is illustrated by Figure 4, and the results can be found in the EPD for Lonbakken Mek. Verksted (Fet, 2014).
Figure 3. Steel staircase (Fet, 2014).
The total weight, including fastening brackets and bolts, is approximately 4375 kg. The galvanised steel staircase requires indoor assemblage. The product should last for 100 years, and the results from the
Figure 4. Flow diagram for a steel staircase (Fet, 2014).
analysis are presented per 1 kg steel (declared unit), while the functional unit is defined as per kg building steel structure with an expected service life of 100 years. All calculated environmental impacts (GHG- emissions) from the products life cycle are adjusted to the declared or functional unit.
The life cycle phases in Figure 4 are described by A1-A3 for the production phase, A4-A5 for the transport and on-site assembly, B1-B7 for the use-phase, C1-C3 the end-of life treatment, and finally, D represents a possible system in which the steel output from the end-of-life is recycled, and from which an environmental credit is attained and given to this system. System boundaries are found in the flow diagram. Waste flows, especially cut-offs from the steel manufacturing in A3, are treated within the module they occur.
Cut-off rules and allocation
All major raw materials and all the essential energy is included. Raw materials and energy flows that are included with very small amounts (< 1%) are to be omitted, however, this cut-off rale does not apply for hazardous materials and substances. The allocation is made in accordance with the provisions of EN 15804 (CEN, 2012). Incoming energy, water and waste production in-house are allocated equally among all products through mass allocation. Since the recycled materials used in the product system have no inherent difference in chemical properties from the virgin material they are replacing, they can be treated as per the ISO 14044:2006 guidelines for the closed-loop allocation in an open system. Therefore, all environmental impacts, energy and resource use associated with the production of the recycled materials are allocated to the original product that generated the recycled material.
The scenarios in the different life cycle stages are described by the following information. Truck transport is modelled using a generic 32 t truck dataset for European conditions, as truck sizes will vary depending on the delivery. A conservative approach has therefore been taken, in order to ensure that emissions are not underreported. The distance is measured by the manufacturer, which is the distance from the production site to the site where the steel staircase will be assembled. Transport in A4 is calculated as the actual estimated distance. To account for the impacts generated in the construction phase, electricity has been allocated to the phase by a fraction of 1/3 of the manufacturing phase (A3). With a standard coating thickness in an inland environment, the scenario for the use stages B2-B5 does not include maintenance, repair, replacement or refurbishment over a 100-year horizon.
Electricity used in the manufacturing processes was accounted for using an electricity mix process specific to Norway, giving a GHG-emission factor 0,0172 kg CO,-equivalent per MJ used energy.
Carbon Footprint of the Product (CFP)
As seen from Table 2, the mam contributions to GWP come from the production stage A1-A3. A smaller amount comes fr om transportation, given for this particular scenario. There is a negative value at the D (recovery) phase. This is an environmental credit, whereby we observe CO,-equivalent uptake into the system through the recycling of steel.
CFP as an Instrument for Reducing Carbon Footprint in the Value Chain of a System
This chapter started with the concept of “bringing a system into being”, and using system as a synonym for a product. Products in this case are interpreted as physical man-made systems; however, it can also be interpreted as a sendee. Through the principles of SE, a specification of the product performance along the entire value chain of the product should be prepared based upon a set of defined needs and requirements.
The life cycle value chain of a system might be quite complex, consisting of a set of subsystems, which again represent a combination of many processes and material flows as demonstrated by the classes Al-5, Bl-7, Cl-4 and D. as shown in Table 1 of the case study. Hie CFP-study should report the results of the analyses of each subsystem and, by summing up the report, give information about where in the life cycle of the product the GHG-emissions occur, which module or subsystem gives the highest impact to the CFP. and where there might be potential for GHG-reductions.
Low hanging fruit can be realised by identifying alternative sub-systems, or modules, which have reduced GWP whilst still meeting the needs and requirements in terms of the product’s design. Incentives to investigate where in the system GHG-reductiou can be realised become stronger in the face of carbon taxing and stricter requirements in environmental documentation. On the other hand, the recycling phase of the system can help to reduce GHG-emissions across the whole life cycle of the product.
If the requirements described in the early design phase also include requirements to a CFP below a certain level, then a CFP-report can be used as a decision supporting tool for setting the priorities for which module of the product and where in the product life cycle the potential of reducing the CFP is highest. Results from a CFP-report can be fed back to the design phase where the choices of materials in the actual product take place. Similar for the design of the entire value chain, a CFP-report will contain an overview of the impact caused duiing raw-material extraction, dining pre-production, transportation, etc., and. thereby, give input to the process of designing the supply chain of the product. The ring or feedback structure is the most typical of the patterns in the analytical methods in SE. In the design of a product, the availability of suppliers, the costs of materials, etc., will determine the design of
Table 2. Calculated contribution to GWP from each of the subsystems per 1 kg of steel staircase produced.
the value chain of the products. However, the market situation can often change this pattern, since the choice of suppliers may vary according to new market availability. Similarly, the energy mix, the access to infrastructure and to transport solutions will change over time. To get an optimal solution regarding CFP, all changes in the system must be included in the analyses for GHG-emissions or reductions, and information should be fed back to the decision maker. Such structures are typical in trade-off analyses where iteration is done until an optimal solution or design according to specified needs and requirements is accepted.
The CFP is only one of a variety of environmental impacts that can arise from a product’s life cycle. CFP should not be the sole component of a decision-making process for product improvement. However, in this chapter the focus is on impacts from GHGs, and not the full set of impact categories as seen in an EPD.