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Purmerend's network resurrection

Purmerend, Netherlands
District Heating 2.0
Purmerend's network resurrection
Purmerend's network resurrection
Purmerend's network resurrection
Purmerend's network resurrection
Purmerend's network resurrection
Purmerend's network resurrection
Purmerend's network resurrection
Purmerend's network resurrection
Purmerend's network resurrection

As one of the largest DH projects in The Netherlands, Purmerend shows how a corroded and under-capacitated network, suffering from heavy leakages and energy losses, could be re-engineered in a smart solution that is sustainable, reliable and highly valued by its users. Thanks to the close cooperation of Thermaflex and Stadsverwarming Purmerend (SVP), the local district heating supplier, 25,000 users so far can benefit from affordable heat and potable water.

The district-heating network in Purmerend is situated in an area with a high ground water level, so the old steel pipes of the district heating network suffered heavily from the corrosion that resulted from this, and its damage to the insulation. This emphasized the need to switch to plastic pipes. Purmerend also wanted to make the district-heating network sustainable, yet economical. They wanted to be prepared for the future, when they would like to use biomass and geothermal energy for heating purposes. Their major problem: connections located in difficult crawling spaces underneath the houses where Dutch legislation does not even allow for steel welding.


In May 2010 a newly engineered network was designed with a reduced need for materials, time and labor, using our flexible, pre-insulated Flexalen pipes with easy house connections (Flexalink). The situation in Purmerend was complex. With the new approach, Slimnet, everything was calculated accurately and every step taken with care. A pilot project was started, and quickly persuaded both the municipality and SVP that Flexalink was the best possible solution for Purmerend. In 5 years time, 4,000 houses were connected to the district-heating network. The switch to green, clean energy was made in cooperation with the National Forestry Commission for the supply of biomass. Starting from 2014, they have provided 100,000 tons of woodchips per year for the production of clean, sustainable heat. This way, 80% of the users will be supplied by sustainable heat, saving 50,000 tons of CO2.


A fast renovation was needed to keep the downtime of the heating/hot water supply short. Speed and space conditions were crucial to keep the disturbances to a minimum for the local government and the residents of Purmerend. The existing district-heating network in Purmerend failed to meet the performance demands, so the focus was laid on improving heat loss and securing a full-proof and hassle-free district heating network.

“We didn’t just look at the parts to be replaced, but used the opportunity to redesign the complete district heating network. Thermaflex’ pipes have smaller diameters, but secured much greater heat returns compared to our old steel system. This way we were able to lower the nominal pressure with almost 1 bar. This meant less water was needed in the network and very attractive energy savings.” Martijn van Lier, Technical Manager at SVP explains.


An exceptionally fast connection of about 4,000 houses meant there was very little disturbance for the local residents. Initially, they had been particularly sceptical due to the earlier issues with the network, but ultimately they were positive and grateful of the renovation project once the results became clear.


Precise pre-fabrication per section made it particularly easy for the installer to plan the implementation and reduce time and space requirements. Complaints quickly dropped and the maintenance scheme of the network drastically changed, as maintenance was minimized.


Main advantages for SVP:

  • Ambitious renovation targets were met, due to high-speed house connections with minimal disturbance, leading to positive end-user response
  • Installation staff trained by Thermaflex
  • Reduced impact on the environment due to rapid installation
  • Long term reliable performance due to prefabrication and factory pressure tests

“In our situation, a plastic piping system was recommended. It is highly resistant against humid conditions, and can also be delivered in long lengths. This was an important asset in our existing environment so as to minimize the disturbance for the residents” declares van Lier.

Our additional contribution:

  • Joint development of a renovation concept avoiding open flame connections in the crawl spaces
  • Development of a high speed installation concept
  • Tailor-made Flexalink for quick, easy, and secure house connections
  • Installation trainings/on site supervision for HAK (pipe installers)
  • Project preparation (material lists, network design, logistics)
  • Pre-fabricated and customized supply of materials


SVP - Stadsverwarming Purmerend (Heat supplier/Network operator)

HAK (Contractor)

Additional Info

Read the full article here or check out the video below (in Dutch).

  • 4000 homes
  • reconnected
  • 50000 tons
  • of CO² saved
  • 84 %
  • cut in unplanned maintenance
  • 50 %
  • cut in water supply
  • 10 %
  • cut in heat loss
    5 years
    Christian Broks
    Regional DHC specialist
    Sub.: Thermaflex Netherlands
    Purmerend, Netherlands
    0066dda5 7659 4da3 830a 743637e5af6a

    Get in touch

    Thermaflex International
    +31 416 567 777
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      New ‘Slimnet’ for 4,000 homes is blueprint for the future PDF 562 KB Preview Download Mail

    Purmerend’s district heating resurrection at steep returns: In September 2015, the multiannual renovation project for 4,000 homes concluded for the city of Purmerend, the Netherlands. The cooperation between Thermaflex and local district heating company Stadsverwarming Purmerend saw the successful end of SVP’s ‘SlimNet’ program, aimed at reviving Purmerend’s deteriorated district heating network. Read the full article here.

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      Successful in the past - prepared for the future (PBPSA) PDF 1619 KB Preview Download Mail

    This brochure is giving an introduction to Polybutene including a review of the performance of Polybutene pressure piping systems in meeting the needs of sustainable building regulations.

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