THUMBS UP aims to develop and demonstrate thermal energy storage (TES) at daily (based on environmental friendly PCM) and weekly level (based on TCM sorption technology) solutions to be easily integrated in EU buildings (both connected and not-connected to DHN) to increase their energy efficiency as well as to exploit Power-to-Heat (PtH) approaches also to make EU Buildings as grid flexibility actors. THUMBS UP wants to overcome all the limits of state-of-the-art building-integrated PCM and TCM TES technologies, increasing TES energy density and reducing CAPEX. THUMBS UP innovates at different levels, from modelling to materials and enhance heat exchanger solutions, targeting demonstration at TRL 7. High-performance TES solutions part of an EU sustainable economy is a factor at the core of THUMBS UP. The project develops truly i) bio-based PCMs from raw materials currently wasted in the EU food industry, turning them into valuable TES materials and ii) TCMs relying exclusively on non-hazardous materials and on water as working fluid. THUMBS UP TES will be demonstrated in 3 demosites (a single-family building in Spain and 2 multi-family buildings in Sweden/Spain) in different EU climates and energy market contexts also to assess THUMBS UP replication potential in two replication sites (ITA, NL). Via its demonstration and replication campaign, THUMBS UP promotes TES role as key enabling technology to optimize thermal comfort and energy efficiency in buildings as well as to promote PtH as facilitator of RES grid integration in a sector coupling approach, to be studied via innovative modelling tools. THUMBS UP gives specific attention to how to fully integrate TES solutions into buildings and wider smart energy networks by combining the technology advancements with TES-tailored digital innovations. THUMBS UP widens the capability to control, monitor and forecasts how to operate building-integrated TES systems to provide services toward both the H&C and power sector.