How does district energy work?

Local eco-systems for more efficient, sustainable communities

What are district energy systems?

District energy systems are local energy networks that provide heating and cooling to buildings in their district. They do this by supplying hot water or steam for heating systems, and chilled water for air conditioning.

They are an efficient and cost-effective way to reduce the carbon footprint of built-up areas like city centres and industrial parks.
ENGIE has completed over 380 district heating and cooling networks around the world. We have several exciting projects underway in Australia.

How does district energy work?

District Heating

One of the most efficient way to decarbonise cities.

A district heating network is a system that produces heat from a central location using gas, renewable energy or waste heat. Underground pipes then deliver hot water or steam to the heating and hot water systems in buildings in a closed loop. The water is returned to the plant to be heated and returned again and again.

District heating networks can be fed by a diverse range of often renewable, or waste heat, sources including:

  • Waste heat from power stations or industrial processes
  • Energy from waste (EfW) facilities
  • Biomass and biogas fueled boilers and CHP plants
  • Gas-fired CHP units
  • Fuel cells or solar thermal
  • Heat pumps
  • Geothermal sources when available
  • Electric boilers (usually from wind or PV renewable electricity)
District Cooling

The solution for sustainable cities or industrial parks.

A district cooling system produces chilled water in a central location then distributes it to buildings through pipes for their air conditioning. The system comprises:

  • Central chiller plant: generating chilled water for cooling purposes
  • Distribution network: distributing chilled water to buildings
  • Energy transfer station: interface with the buildings’ own air‑conditioning circuits

Pros

District Heating

  • Efficient generation and use of heat for a wide variety of customers
  • Lowering costs of energy generation
  • Fuel flexibility and access to otherwise lost waste heat sources
  • Many energy sources and generation redundancy increases reliability and efficiency
  • Reduced maintenance compares to individual systems
  • Price stability
  • Reduced carbon footprint
  • Freeing up space and reducing the building energy demand (no need for boilers, gas or electricity supply)
  • Less CO2 emissions
  • Renewable energy integration
  • Reduction of noise and space saving on roofs
  • Preservation of the architectural heritage
  • Improvement in energy efficiency
  • No upfront capital cost for the customer
  • Risk transfer to an expert

Pros

District Cooling

  • Less CO2 emissions
  • Reduction of primary energy consumption
  • Controlled and optimized use of chemicals
  • Less chemicals
  • Improvement in energy efficiency
  • Renewable energy integration
  • Reduction of noise and space saving on roofs
  • Preservation of the architectural heritage
  • Control of the collective health risk
  • Reduction of the heat island effect
  • Improved reliability
  • Reduction of building electricity demand
  • No upfront capital cost for the customer
  • Risk transfer to an expert
Often, district energy systems are connected to combined heat and power (CHP) plants
CHP plants are also known as cogeneration plants
CHP plants generate electric power in addition to heating
They can achieve energy efficiencies above 80%
District energy systems operate 24/7/365 and have the ability to withstand major events such as earthquakes and severe weather without interruption