This paper introduces a methodology to the design of an underground heat exchanger connecting a datacenter - the heat source - to office buildings - the heat sinks. The underground network is a loop through which a baseline mass flow rate of water is circulating, while the buildings heat pumps are directly connected to the loop. Different configurations are examined, based on maximum heat transfer rates and minimum pumping power. The flow system configuration is determined with the objective of distributing to the office buildings the enthalpy dumped by the datacenter to the system. (C) 2016 Elsevier Ltd. All rights reserved.