In this project, the extension of the existing cooling capacity was realised with an Aquifer Thermal Energy Storage (ATES) instead of a conventional chiller. Compared with a chiller, the use of ATES reduced the electricity consumption for cooling by 50%. Moreover, the heat that was extracted from the ventilation supply air in summer was stored in the aquifer to be utilised in winter for (pre)heating ventilation air. The integration of the ATES system in the installation with 2 chillers enabled also short-term cold storage in summer. Therefore, the risk of cold shortage due to climatic influences (warm summer and/or mild winter), was compensated for without costly investments in extra chiller capacity. Furthermore, the combined use of the aquifer system for seasonal cold and heat storage, as well as short-term cold storage made the system more profitable. Consequently ATES can also be attractive for smaller projects with existing cooling systems that have to be extended. Therefore, this will enlarge the market potential for ATES. For instance, in the first half of summer 1994 (April, May, June and July) the storage delivered 256 MWhth (megawatt hours of heat) cold and 82,000 kWhe (kilowatt hours of electricity) were saved. No additional cooling was applied thanks to the lower temperature in the cold storage.

The project demonstrated:

- That the required extension of the cooling capacity in the hospital can be realised by storage or "winter cold" in a sand-layer (aquifer) in the soil, and that such a storage system can be integrated in the existing cooling system.

- The technical and economical feasibility of combined seasonal cold and heat storage in an aquifer for cooling and (pre)heating ventilation supply air.

- And the advantages of using the aquifer for short time storage of cold that is loaded at night with the available chillers, thus creating extra facilities for energy management and compensating for risks of cold shortage due to climatic influences.