Interleuven, a partnership of municipalities in the arrondissement of Leuven, together with the municipality of Tervuren, is realising the new and innovative sustainable business park Keiberg-Vossem. _x000D_ For the business park, there is the ambition to be as self-sufficient as possible in terms of energy based on solar energy with possible residual heat as extra input. To this end, the site invests in generating and storing renewable energy. _x000D_ The heat produced via PV and solar collectors (later residual heat from a company) during sunny periods is stored in an underground water basin and is available for heating in the cold periods. Because of this storage, the heat demand in cold periods can largely be covered by its production during sunny periods. Due to this local production, storage and linking of supply and demand on the site, the impact on the electricity grid is very limited. This way of working prevents ‘inconvenience’ from a new business park to the electricity grid and ensures that the energy needs are largely covered by renewable sources. _x000D_ Heat currently accounts for the majority of Flemish energy consumption. For example, in 2019, Flanders needed 122 TWh of heat and ‘only’ 48 TWh of electricity. For small-scale to medium-sized solutions, the main focus for the time being has been on heat pumps and beo fields (storage in the ground). However, the storage of heat in an underground water buffer has the potential to significantly increase and make more sustainable the degree of self-sufficiency in energy for, for example, business parks, residential areas and apartments. _x000D_ Interleuven is not about one night of ice and is now investing heavily in a common infrastructure that will be managed in consultation with the companies. The aim is to promote cooperation between relevant governments and companies and to form a renewable energy community, in which companies and the developer / manager participate. _x000D_ Concretely, on the Keiberg-Vossem business park, a new SME zone of 4.5 hectares net with 1300m3 of heat buffer basins under the ground will be realized. The water in it is heated to 85 degrees Celsius. On top is a parking lot with electric chargers and PV production. All the buildings on the site are filled with PV and solar collectors that feed the buffer in the summer, both directly and via a heat pump. In addition, heat is also stored that is released during the cooling of the buildings in the summer. As a third source of heat, the possibility is kept open to link residual heat from companies that will settle on the site to the collective heat system. Due to the winter availability of high temperature in the heat buffer, no upgrade with heat pumps will be required of low temperature heat as is the case with heat pumps. The peak consumption of electricity on cold days is therefore limited by the heat buffer system. _x000D_ The heat buffer will be operational in early 2025 and one more cycle can be monitored. This information, together with the cost-benefit analysis, will allow Interleuven and other interested parties to use this heat buffer and installations as a reference and example project. _x000D_