Architecture, Engineering and Construction are currently undergoing an energy-digital transition towards a decarbonised and sustainable scene. Energy assessment of buildings through Building Energy Modelling tools allows for in-depth analyses for energy optimization and establishing quantitative proposals for building improvement. This paper shows a comparative study of three programs used for energy simulation of buildings: TRNSYS, HULC and SG SAVE. They have been applied to four Research and Development (R&D) Projects: the energy assessment of a hospital, the energy behaviour of two partially recycled construction materials, and the cost-effectiveness study of energy efficiency measures and renewable energy at the district level, to validate their handling, precision, and result reliability. The comparative assessment shows SG SAVE is the best-valued software: it is free and easy to use, complies with the Spanish energy regulations more easily than HULC, and along with Open Studio makes complex calculations similar to TRNSYS.
