The HEATWISE project aims to tackle various thermal management challenges in tertiary buildings with a significant IT load. The project has specific objectives to develop and validate (to TRL 4 and 5) its technological innovation in two interrelated aspects: for IT system equipment in facility rooms and for a complete building management level. The innovation toward achieving energy efficiency and thermal management optimization follows up on a detailed thermal need analysis framework and theoretical validation, and is fulfilled through four novel solutions: i) Hybrid future-proof cooling hardware solution for high-density data processing based on two-phase dielectric liquid cooling and air immersion ii) Digital twin-supported holistic high-density data processing management system with a smart workload orchestration system, iii) Integrated multi-objective building energy management system covering both IT equipment needs and human presence, and iv) Self-assessment tool for energy management needs in tertiary buildings with power-intensive IT systems. On top of that, the project will develop a knowledge-sharing platform to showcase potential improvement pathways in energy optimization of tertiary buildings and maximize the project's impact. The project consortium consists of 12 partners from 8 different countries across the EU and with a more global inclusion; including 3 universities, 3 research centers, 4 SMEs, 1 large company, and 1 national standardization body, making sure that all the required expertise for a successful accomplishment of the project and future exploitation exist, and the partners complement each other in the most optimal manner. The technologies will be demonstrated in different specific designs and integrations in a university, a supercomputing research centre, industrial and office buildings, in Denmark, Poland, Turkey, and Switzerland, with extended investigations for medical centres and hotels as impactful tertiary building categories.