Purmerend is Dutch city of 80,000 inhabitants, located just north of Amsterdam. In its search for more sustainable and reliable heating solutions, the city opted for biomass-powered district heating for its citizens’ energy system. Today, around 75% of all buildings are connected to the district-heating network.

Purmerend’s geography makes this system particularly unique. The city, as many others in the Netherlands, lies below sea level and is crossed by dikes and canals, which required a tailored approach. The 600km network works in fact with a sub-stations system,  often located in areas enclosed by dikes. Each substation typically supplies 200–500 customers, including some unusual households: several houseboats are also integrated into the system.

Heat is produced by three plants. The main unit is a 44 MWth biomass boiler whch supplies around 80% of the city’s heat demand, while two gas-fired units provide reserve and peak capacity.

Like many large district-heating networks, Purmerend faces challenges such as peak loads and high-temperature operation, which can lead to heat losses. However, the city has already taken significant steps to improve the system. Replacing aging pipes with modern pre-insulated pipelines has reduced heat losses by 10%, cut water consumption by 50%, and decreased unplanned outages by 84%. Further optimisation is underway.

By lowering operating temperatures and improving return-water performance, Purmerend aims to reduce losses even more and enhance overall efficiency. Despite these challenges, the system remains one of the most advanced and successful district-heating examples in the Netherlands.