The research in energy efficient and sustainable technologies for buildings is currently an important issue because of their high-energy consumption. In this regard, VO₂-based thermochromic windows are showing promising results in terms of their energy savings ability. However, no previous study has investigated their life cycle environmental impacts and, in order to develop a sustainable product from its foundations, these environmental issues should be accounted since the early stage development. Therefore, the first objective of this work is to conduct a life cycle assessment (LCA) of VO₂-based technologies for passive thermal control. Moreover, a second objective is to address a more generic question related to the use of prospective LCA in early stage research in materials engineering laboratories. For this purpose, a comparative LCA between a VO₂-based thermochromic window and a standard window is performed, studying the environmental impacts from the VO₂ production until the end-of-life. The nonrenewable and renewable cumulative energy demands as well as the impact on climate change are studied. Results show that there is a positive balance between the thermochromic and the standard window environmental impacts. Moreover, guidance to lower the environmental impacts associated to the production phase is given.