Life Cycle Assessment and Materiality Assessment Part 3 – What do the numbers mean to you? Posted March 17, 2017 by Julie Sinistore In Part One of this blog series we covered what a Life Cycle Assessment (LCA) is and the importance of a materiality assessment. In Part Two we delved into how to set up an LCA study. We will now explore what the final results might look like and how they can be used. We will continue building on the milk container example explored in Parts One and Two. If the goal is to reduce the overall impacts from the life cycle of the product, than a lower score indicates a lower impact. The goal is to come up with the smallest score or footprint possible. Big is bad. Therefore, important impacts get higher weighting. With that in mind and using the data and weightings in the table below, I created a very simple scoring system for GHG emissions, package recycling and product waste. The glass container has the highest GHG emissions, so if that is set to 100% and the GHG emissions from the other two containers are normalized to that, you get the percentages in the table. When I apply my weighting system, I multiply the weight (8 for GHGs, 10 for food waste and, 7 for recyclability) by the percentage for that category. The final score is the summation of the weight times the percentage for each category. For example, the equation for glass is (100%*8) + (66%*7) + (35%*10) = 16. Using this same method, the score for plastic is 11 and the score for aseptic pack is 9. According to what is important to me, I should choose aseptic pack. Under this system, but using someone else’s weighting, glass gets a score of 12, plastic 9 and aseptic pack 11. Glass is still not favorable, but now their choice is plastic over aseptic pack. While this is an over-simplified example, it illustrates the point that disparate stakeholders can value environmental impacts in different ways. The numbers alone do not tell the whole story. Also, there can be impacts from the life cycle of the product that are not directly measured by LCA (e.g., product spoilage), but which are more important to consumers than impacts that are directly measured by LCA. Finally, if other impacts that can be measured with an LCA were included, such as water use, water quality and, air quality, the calculation could become quite complex, but result in a more holistic assessment of the product system. Consumers are not the only ones who find this type of analysis useful. If I were a glass or plastic bottle manufacturer, this information would tell me that I need to focus on reducing the GHG emissions from the production, use and disposal of my product. Similarly, if I were the producer of aseptic packaging, this information would guide me to focus on the recyclability of my product. If this discussion makes you wonder what the life cycle impacts of your company’s product or service are and how stakeholders might weight those impacts differently, consider conducting an LCA and a materiality assessment together to gain greater insight and set improvement targets that will have the greatest positive impact. Read Part 1 – Life cycle assessment and materiality assessment – should I cry over spilled milk? Read Part 2 – Life cycle assessment and materiality assessment – setting up the study.