Building Retrofit Marginal Abatement Cost Curve (2D)

The 3D version of this simulator renders a city's building stock as a live skyline and lets buildings light up as they're retrofitted. This 2D companion goes straight to the chart real municipal retrofit programs are actually planned against: a marginal abatement cost curve (MACC), the staircase of cost-per-ton bars sorted cheapest-first that shows exactly how far a fixed annual budget reaches into a city's total abatement potential. The same budget-constrained greedy allocation and Wright's-law bulk-procurement learning curve drive both simulators, but here the learning curve and the cumulative CO2-avoided impact tally are drawn out explicitly as their own charts rather than folded into a spatial scene — set the budget, prioritization strategy and learning rate and watch the curve, the learning-cost scatter and the impact strip settle together year by year.