This is a relic from a change we did during the early days. When Geodesignhub was just launched, we used to have a classic “Attractiveness” / “Vulnerability” type evaluation maps. So every system was either classified as one of the above two type of systems. e.g. Commerce would be classified as “Attractiveness” type system i.e. interventions would be encouraged where it is most attractive. In the same way Green Infrastructure would be classified as “Vulnerability” type system where interventions should be prioritized to the most vulnerable locations.
In this type of classification, we had a a five level evaluation map from “most attractive -> least attractive” and from “most vulnerable -> least vulnerable”. So to demonstrated the impact of someone putting something at the most attractive site, the impact had a +1 color and viceversa for least attractive, so there are 7 impact colors. We switched the evaluation maps to a “ordinal” scale, partly because the attractiveness / vulnerability confusion. e.g. Which type do you think “Agriculture as a business” is? Using the current scale these questions are solved easily and are also easy to understand for people not familiar with GIS. But this means that the scale is unbalanced: one red, one yellow and three greens. Therefore we dont really need the seven impact colors.
Generally impact analysis is one of the weakest portion of the system (by design), it is meant to be crude and simplistic. We recommend for any sophisticated impact analysis, you take you all data and use other software or link that software with Geodesignhub using the API.
Hope this helps, please let me know if you have further questions.