This simulation illustrates the accuracy of our heat solver by testing how well it observes the Law of Conservation of Energy (aka the First Law of Thermodynamics). The following model simulates a completely insulative system (i.e., no heat in, no heat out) using a thermal boundary of zero heat flux. As you can see, as the time step increases, the precision decreases. But a small time step (0.01s) is capable of maintaining the total thermal energy at a level as accurate as 99.99% for as long as the simulation runs, regardless of the complexity of the structures in the system!