Have you done the math that shows that the centralized "long time to heat-up" system, even assuming a certain amount of wasted heat, is actually less efficient

Have you done the math that shows that the centralized "long time to heat-up" system, even assuming a certain amount of wasted heat, is actually less efficient than per-unit, fast-to-heat-up system? It's quite possible that 1. the loss from people opening their windows because it's too hot is still actually less than the loss of having a per-unit heating system. 2. the expense of adapting the system to allow per-unit controls is actually higher than the loss of people opening their windows because it's too hot. I mean, it's also possible that the decision to centralize it was based on false assumptions, and that it actually is less efficient. But never underestimate the power of efficiencies of scale.