Functional Unit – What do we mean? How does it help us? GREENLIGHT ALLIANCE IRENE MAZZEI, PHD.
As the way ahead becomes a little bit clearer in terms of sustainability metrics, we start to dive deeper into key features that allow data to be used more easily in a wider variety of scenarios. In this case, the Functional Unit.
The last few articles in this series focused on the definition of Life Cycle Assessment (LCA) and its use as environmental impact quantification methodology, but also on the way we can apply it to lighting products. Considering the complexity of LCA, it is important that common awareness and understanding is built in industrial settings regarding this methodology and how to process the information we obtain from it. As life cycle thinking and LCA-based reporting are starting to make their way into product information requirements and B2C communication, some questions inevitably arise on the most appropriate use of this information, especially regarding comparing results for products. It is important to keep in mind that any comparison exercise must be based on results obtained following the same methodology, rules, assumptions and datasets. Research has been carried out showing that variations in LCA results were observed when different Product Category Rules (PCR) [1], databases [2] and assessment methods [3] were applied. However, when handed over a report containing LCA results, such as an Environmental Product Declaration (EPD), it is generally not possible to know all the detailed methodological choices that led to those results; this is also why it is recommended not to compare EPD results across different EPD programs. Focusing on EPDs – which are starting to be more 112 / 113
and more adopted in the lighting industry – as described in a previous article in this series, the endorsement by LightingEurope of PEP Ecopassport’s PSR0014 [4] as the most complete and robust PCR for lighting products wishes to achieve a more standardised approach to lighting LCA to produce EPDs. This would reduce and ideally eliminate the result variability associated with LCA rules, thus supporting more significant product comparison exercises. Included in PSR0014 guidelines is the definition of a Functional Unit (FU) for lighting products. A Functional Unit describes a quantity of a product based on the performance it delivers in its intended application; to explain this concept, let’s consider a simple example: We would like to define a Functional Unit for the LCA of laundry detergent. The function of the product is to wash clothes, therefore a valid Functional Unit could be “washing 50 standard laundry loads”. A less useful Functional Unit would be “one bottle of laundry detergent”. In the first example, the validity of the FU is connected to the fact that the environmental impacts declared in the EPD can be reported in relation to the use we make of the product, which remains consistent and independent on the characteristics of the product. Therefore, if the function that one unit of our specific product can fulfil (i.e. the Declared Unit (DU)