A building reduces to a function
An energy model answers one question per run. A surrogate — a single function fitted to a small, deliberately chosen set of full simulations — answers in a millisecond, as many times as you like. The article is about how one is built, and mostly about how you check that it is telling the truth, which is the part nobody writes down.
- The problem: why a handful of variables is already thousands of runs.
- The idea, and what is actually being traded away.
- How one is built — choosing the variables, sampling, fitting, encoding.
- How it is checked. Against runs it has never seen.
- What it unlocks: sensitivity, optimisation, an answer in the sketch phase.
- Where it stops. Interpolation only, one model per building, and never the reported number.
No date. It publishes when the runs behind it are finished and checked, and not before.