The heat generating plant in Malbork began operating in the mid-1960s. In 1991, an independent company, Przedsiębiorstwo Energetyki Cieplnej in Malbork was set up; six years later, it became the property of the Malbork district. When ECO SA took over the majority stake in May 2007 the company changed its name to ECO Malbork Sp. z o.o.
The operations include the towns of Malbork and Prabuty, as well as Ryjewo district. It produces and supplies heat according to the high standards applicable within the entire ECO Group. Currently, the company's priority is to expand the network and to reach to as many clients as possible, providing ease of access worthy of a 21st century consumer. This is facilitated by the Integrated Management System, based on such standards as the ISO 9001:2000 quality management standard, the ISO 14001:2000 environment management standard and the PN-N18001:2004 safety management norm.