Certification systems like LEED and BREEAM award a fixed number of points per category for measurable design choices (better glazing, low-flow fixtures, recycled materials, daylighting, native landscaping…). The building's total score decides its tier, and — critically — extra points get more expensive the more you already have: the easy, cheap wins get claimed first, and each additional point in a category demands a deeper, costlier intervention.
cost(p) = k · p^1.6 (per category, k = category's $/point base rate)
total cost = Σ cost(p_i) over the 6 categories
tier: 40+ Certified · 50+ Silver · 60+ Gold · 80+ Platinum (of 100)
- Category sliders — how many of each category's available points you pursue. Point towers on the right grow to match; unfilled slots stay dim outlines.
- Power-law cost — going from 5→6 points costs far less than 25→26 points in the same category, reflecting real diminishing returns (the cheap credits — bike racks, low-flow toilets — run out fast; the expensive ones — deep envelope retrofits, on-site renewables — don't).
- Budget cap — the money you actually have. Categories that push total cost over the cap turn red; the sim does not stop you, so you can see exactly how far over you'd go.
- Auto-fill — greedily buys whichever category's next point is cheapest until Gold (60 pts) is reached or the budget runs out, a simple demonstration of cost-effective credit-chasing.
Real-world relevance: this is the actual trade-off a project team faces when targeting a certification tier — where to spend a limited green-building premium for the most points per dollar.