London District Energy Collective Agreement
The largest district heating network in Romania is located in Bucharest. Owned and operated by RADET, it distributes about 24 PJ per year and serves 570,000 households. This represents 68% of Bucharest`s total heat demand (RADET represents 4% more thanks to built-in boilers, or 72% in total). On the other hand, the Pro union and the Finnish Association of Engineers are parties to the collective agreement of energy sector employees, which were joined by the municipal unions (JHL, Tekniikka ja Terveys KTN and the Jyty Public and Private Sector Employees Association). A fifth-generation district heating and cooling system (5GDHC), , also known as cold heat, distributes heat at an almost terrestrial temperature: this minimizes ground heat loss and reduces the need for extensive insulation. Each building in the system uses a heat pump in its own installation room to extract heat from the surrounding circuit when it needs heat, and uses the same heat pump in reverse to release heat when it needs cooling. In this way, the residual heat can be recycled from cooling into buildings that must be heated in a „heat separation network“.  The total temperature inside the ambient circuit is controlled by heat exchange with an aquifer or other water source in order to remain within a temperature range of between 10 and 25 degrees Celsius. The fourth generation is being developed with the transition to the fourth generation, which is already underway in Denmark.  The fourth generation aims to combat climate change and integrate a high proportion of renewable energy into district heating by providing great flexibility to the electricity grid.  Compared to previous generations, temperature levels have been reduced to increase the energy efficiency of the system with supply temperatures of 70oC and lower. Potential sources of heat are industry residual heat, waste-burning cogeneration facilities, biomass power plants, geothermal and solar thermal energy (central solar heating), large-scale heat pumps, residual heat from refrigeration plants and data centres, and other sustainable energy sources.
These energy sources and large-scale thermal storage, including seasonal thermal energy storage, aim to provide flexibility to fourth-generation district heating systems to balance wind and solar power generation, for example by using heat pumps to integrate excess energy when there is a lot of wind energy, or by providing electricity from biomass power plants when electricity is needed.  As a result, large-scale heat pumps are considered a key technology for smart energy systems, with a high proportion of renewable energy up to 100% and advanced fourth-generation useful heat systems.    The first heat pump was installed in Stockholm in 1977 to provide district heating from IBM servers. Today, the installed capacity is about 660 MW of heat, using treated wastewater, seawater, remote cooling, data centers and grocery stores as heat sources.  Another example is the Drammen Fjernvarme district heating project in Norway, which produces 14 MW of water at just 8oC, and industrial heat pumps are demonstrated for district heating systems. Among the possibilities for the use of industrial heat pumps, it should be noted that, as conditions vary from city to city, each district heating system is unique. In addition, nations have different access to primary energy sources and therefore have a different approach to how to approach heating markets within their borders.