This Insights paper highlights recent findings of ESIPP research on the use and development of simulation, optimisation, and artificial intelligence-based data-driven techniques for modelling building and energy systems at different scales. The methodologies presented in this Insights paper can facilitate building energy refurbishment decision-making and accelerate technical solutions for different building energy retrofit scenarios. This will aid the development of future energy policy scenarios, support decreasing the carbon footprint of the building sector, and facilitate renewable energy integration and demand response implementation of the housing stock by 2050.