Goal: Quantify the environmental impacts of your product and compare different scenarios.
One of the best ways to quantify the environmental impacts of your product or service is life-cycle assessment (LCA). A carbon footprint is a kind of LCA that only measures greenhouse gas emissions, but LCAs can quantify and compare many different types of environmental impacts, from carcinogens to land use to mineral depletion and more. The “ReCiPe” methodology measures eighteen impact categories and can graph them all on one scale for the whole life-cycle of your product. This helps you determine your priorities for green design. For example, here are very rough LCA graphs of typical products in four different product categories:
Rough single-score LCA graphs for four types of products. Image Credit: Faludi MCAD Class 2014
These graphs combine all of the different impact categories mentioned above, to show the biggest opportunities for improvement. For “large electrical” it is reducing energy use or switching to clean energy, and for “housewares and other” (such as furniture), it is choosing better materials and manufacturing methods, etc. However, sometimes the opportunity is not as clear. Notice that in the “often washed apparel” graph, energy and material impacts are similar; in this case, there are large uncertainties for knowing which impact is actually larger.
Watch out: some assumptions can change impacts by orders of magnitude! To avoid this, you can use sensitivity analysis to check your assumptions by trying different inputs or methods. Only trust large differences until you have more precise analyses.
Here is an hour-long video introduction to LCA, describing what it is used for, what is measured, and how to do it:
How To Do LCA
Your estimated LCA for early-stage design will not be rigorous, like the analysis you would need for an Environmental Product Declaration. A properly rigorous LCA can take six months or more to do, but an estimated LCA can take hours. As above, remember rough analyses can have huge uncertainties (such as 30%, 50%, often 100% or more, per datapoint). Only trust large differences until you have more precise analyses. The resources below can be combined with the LCA Exercise so that you can do your own.
You can get a basic working knowledge of how to do LCA from the primer below (similar in content to the video lecture above):
You can learn how to do LCA using SustainableMinds software, using their tutorial. Also note their handy page on how to choose functional units. You can also learn how to do LCA by hand, looking up pre-calculated LCA scores for different materials, manufacturing methods, transportation modes, energy sources, etc., in various publications.
Okala Practitioner is a publication which will teach you to do LCA by hand, with lookup tables and a spreadsheet, and integrate it into your design process. You can use this template spreadsheet, or your own.
Ecolizer 2.0 is a free downloadable table of LCA values. To use it, simply multiply the score per unit by the number of units. For example, if your product uses 2 kg of extruded aluminum and the product gets landfilled at the end of its life, you would look up the impacts per kg of aluminum raw material extraction / production, look up the impacts per kg of extruding aluminum, look up the end-of-life impacts per kg of landfilling aluminum, and multiply them all by two. Then do the same for all other materials, transport, energy, etc., and add it all up. You can use this template spreadsheet, or your own.
This 45-minute video takes you through the exercise linked to below, demonstrating everything step-by-step.