Scores within the fields of fuel game are calculated hierarchically. The overall sustainability score serves as the primary measure of player success, and is calculated as the weighted average value of the three subscores: economic, energy, and environment. Each of these scores is presented as a percentage, with 0 indicating poor performance, and 100 excellent performance. By default the sustainability score is calculated using even weightings of the three other scores, but if the game objectives change, this weighting scheme can be modified in the moderator screen. The calculation of the three subscores is described below.
The economic score is calculated as a function of the player with the most capital on hand. Each players' score reflects the relative proportion of the highest capital; i.e. in a two-player game, if Player A has $10,000 and Player B has $100,000, Player A's economic score is 10%, while Player B's is 100%. Details on how the player's capital is calculated can be found on the Economy Model page.
The energy score is based on the total amount of energy produced or consumed by a farm. The maximum possible amount of net energy gain from refining crops at a field level is estimated to be 2020 GJ, while the maximum energy loss (growing crops without refining them) is approximately 225 GJ. The player's average net energy for all fields is calculated using these bounds to produce a percentage score. Details on how the net energy is calculated can be found on the Energy Model page.
The environmental score is a composite of four different scores, each reflecting the farm's performance in a different environmental metric. These include soil fertility, water quality, insect habitat (measured as bio-control index, or BCI), and CO2 emissions. Each of these elements is calculated using a different environmental sub-model, the result of which is used to compute an individual sub-score for each metric. The sub-scores are calculated as a percentage value by normalizing the player's performance based on the minimum and maximum values possible (just as with the energy values). The overall environmental score is then the average of the four sub-scores. The details of how the sub-models are implemented can be found on the Environmental Models page.