The building's refrigeration machine at the end of its life and the discomfort problems encountered in the past prompted the client and the design office to think about a global approach in the HVAC renovation of this Brussels office building. Given the simultaneous needs for hot and cold, a 4-tube heat pump was installed to cover all the cold needs, and part of the heat needs. In order to ensure that this over-investment is profitable, a 10-year tripartite Energy Performance Contract (EPC) has been drawn up between the customer, the operator and the design office.