| For those users that do not want to use the default weighting factors, we recommend using the mixing triangle. The triangle can be used to graphically depict the outcome of product comparisons for all possible weighting sets. Download free Triangle Tool software Each point within the triangle represents a combination of weights that add up to a 100%. (Click on image to enlarge)  The mixing triangle: The marked weighting point is positioned where Human Health is weighted 50%, Ecosystem Quality 40% and energy Resources 10%. The point is defined by following each side until the dotted flashes leave towards the point in the triangle (based on Hofstetter 1998). A key feature is the possibility to draw lines of indifference. These are lines representing weighting factors for which product A and B have the same environmental loads. The lines of indifference divides the triangle into areas of weighting sets for which product A is
favourable to product B and vice versa. The weighting triangle can display the result of an LCA without knowing the weighting factors. According to Hofstetter, such a representation is a very useful tool to enhance the transparency of the weighting process, as it shows under which conditions (which weighting factors) product A is better than B. The stakeholders do not have to set discrete weights, but they have to agree whether it is plausible that the weights would fulfill the conditions under which A is better than B or not. Such a discussion process turns LCA into a consensus building process, instead of a tool that produces simple single truths. Our mission is not the development of a consensus building tool, but there is no reason not to use this methodology as such, if the conditions facilitate an open discussion with the stakeholders. More information on this subject can be found in [Hofstetter 1999]  The line of indifference in the weighting triangle and the sub-areas with their specific ranking orders (B>A means that alternative B is environmentally superior to A and the eco-index A is higher than B). The Triangle Concept is developed by Patrick Hofstetter, Arthur Braunschweig, Thomas Mettier, Ruedi Müller-Wenk and Olav Tietje, as published in
Journal of Industrial Ecology. Download Triangle Tool |
