KPI GHG intermediate output

[divyasharma-arup]

I think there is likely to be a scaling factor we will need to consider depending on how the sim is configured. In our own sims, buses tend to represent "real world" buses so they can take up the right amount of space in the sim, whereas the number of cars align with the sampled population. So, when we aggregate, we need to "scale back" the car emissions to "real world" numbers so that buses and cars are comparable.

I'm not too clear on the requested solution, but I have the steps below in mind:

1. We need to decide how we handle vehicles that are potentially at different scales in the sim. Ideally a user wouldn't have to think through whether they are looking at "real world" or "sim scale" values, but it should be transparent to them. I think perhaps a user will need to input some specific information, and we will need to be clear that the emissions KPI reflects "real world" values. This means we need to scale the cars to "real world" numbers, and then we can aggregate this safely with bus emissions to get total emissions.
2. It'll be helpful to have the intermediate output show emissions by mode and veh-km if possible. It makes it easier to understand the calculation of the KPI. If that means we have to drop the "emissions per capita" column, that's ok. We should recognise the emissions calculation is likely to evolve in the next few phases of work.

Open to ideas, suggestions.