This co-authored book provides guidance on approaches to the modelling and simulation of energy systems in the built environment. The intention is to equip readers with the understanding required to compose high integrity models, commission realistic simulations, and interpret predictions to assess life cycle performance and ensure operational resilience. To address the myriad of challenges of the clean energy transition, this co-authored book provides guidance on approaches at various scales and complexities to the modelling and simulation of energy systems in the built environment. The intention is to equip readers with the understanding required to compose high integrity models, commission realistic simulations, and interpret predictions to assess life cycle performance and ensure operational resilience. The book describes the modelling and simulation requirements of the often-competing technology approaches that will progressively underpin sustainable energy solutions.