Your loadbox has six surfaces. Most bodybuilders only specify three. While the industry obsesses over roof insulation and ignores floor radiant heat, builds 50mm floors facing 88°C differentials while installing 75mm roofs facing 53°C, and leaves thermal bridges at every mounting point, your TRU runs 40% harder than necessary. ATP Class C certification requires K ≤ 0.40 W/m²·K whole-body thermal performance—a standard South African bodybuilders rarely measure and never guarantee. We calculated the physics, compared four design scenarios, and quantified why the “cheapest” insulation creates the most expensive operation.