by Linda Bertelsen
Hohenberg, aerial view, Isoplus

Sustainability has gained increasing attention and importance in society, including the energy industry. Besides the topic’s importance for district heating providers, the sector aims to contribute to it in the most feasible way. If a pre-insulated pipe network is produced following the EN standards, the customers can expect a very long thermal lifetime. This means choosing a pipe system today is choosing it for the next generation.

By Jens Rasmussen, Technical Manager, Isoplus and Sabrina Fröhlich, PR Head of Marketing, Isoplus

Published in Hot Cool, edition no. 4/2023 | ISSN 0904 9681 |

How can it be ensured the products meet the expectations and demands of the next generation of young people, and what are these?

In the article “The District Heating business model 2050 – possible pathways “, published by DBDH (Danish Board of District Heating) in the HOT|COOL magazine, a group of mixed stakeholders attempted to understand possible future customer values and business models for district heating.

Some of the main outlooks of this study were:

      • Heat supply is completely decarbonized, and it is standard to recover waste heat of both high and low temperatures.
      • We live in a circular economy and, because of circularity, coupled sectors
      • A high level of digitalization is standard

    See the article “The DH business model 2050” in the HOT/COOL magazine, issue no. 3, 2023, published by The Danish Board of District Heating (DBDH)

    How can manufacturers of pre-insulated pipes contribute to these expectations?

        1. Ensure the feedstock delivered downstream within the supply chain has the lowest possible carbon footprint.
          To ensure a long lifetime, pre-insulated pipes are standardized products of very high quality, and this should never be jeopardized. All initiatives concerning design and material properties must fulfill the requirements of EN13941-1.
          A new concept has recently been introduced, offering a solution for a more environmentally friendly PE outer casing. It aims to reduce the carbon footprint caused by district heating networks worldwide.

          The raw material used for this solution is a zero-carbon alternative to traditional fossil-based PE, and it is set to change the production and use of PE in the district heating business. When energy utilities choose this concept, they get the same high-quality PE as they are used to. Still, they get ISCC certificates guaranteeing that the same amount of PE is produced from renewable sources such as plant-based waste materials and used cooking oil for the bought PE.

          With the ISCC-certified PE, you spare the environment 1.9 tons of CO2 per ton of PE* compared with PE based on fossil raw materials, even without compromising the EN 253 norm. The solution is based on the mass balance principle – a major benefit.

          * The CO2 savings were calculated based on the rules laid down in the ISO standards on LCA: ISO 14040:2006, ISO 14044:2006, and ISO 14067:2013

        2. Ensure the production process respects the environmental impact and ensures the upstream transport of the products has the lowest possible carbon footprint.

          The most critical elements of ensuring this are:
          – Electrification of the production and internal transport
          – Heating coming from sustainable local suppliers
          – Increase transport by train whenever possible
          – Fulfillment of the ISO 14001 certification

          The initiatives mentioned above must be an aim for the entire industry. The more that is accomplished in this regard, the more focus can be placed on downstream supply chain efforts to develop and deliver sustainable products.

        3. Secure that the products are recycled for the right purposes.

          Besides enabling the usage of recycled feedstock, recycling the pre-insulated pipe systems after their lifetime must be improved. What are the recycling possibilities for the components of pre-insulated pipes?

          PUR foam
          Both manufacturers of pre-insulated pipe systems and suppliers of the feedstock for foam are researching the possibilities of recycling the PUR foam of the pre-insulated pipes after the end of its lifetime, so far without a breakthrough solution for full-scale production.

          PE outer casing
          To ensure the quality and lifetime of the PE and in accordance with EN253, only non-degraded rework from the manufacturers’ own production process can be recycled and lead back to the new PE outer casing production.
          With a constant demand increase for sustainable products, recycled PE from the manufacturers’ own production doesn’t fulfill the market demand, and the overall availability of feedstock from recycled PE is decreasing.
          The introduced more sustainable concept meets these requirements without compromising the EN253, and the availability of feedstock for plant-based waste materials is not challenged either, according to the suppliers.

          Steel pipe
          Steel accounts for the largest carbon footprint contribution in producing pre-insulated pipe systems. EN13941-1 regulates the quality of the steel pipes needing to be graded P235GH. Many steel mills already provide the market with pipes of steel grade P235GH with a considerable amount of recycled steel.
          Still, there should be a way to reduce the carbon footprint. The steel pipe manufacturing industry must focus on electrifying its production operations, ensuring a sustainable power source.

        4. Focus on digitalization wherever possible.
          To support digitalization within the industry, the possibilities, among others, are:

          – Alarm systems for surveying the network condition concerning if there is a leakage on either the PE outer casing or the steel carrier pipe.
          – Transmitting information from alarm boxes via the GSM network
          Alarm boxes sending information via the GSM network can also forward information other than the alarm measurements, such as water level in wells or other critical champers, temperature, pressure, and flow.
          – Transmitting information via the cu alarm wires embedded in the PUR foam.
          It is even possible to embed a separate wire for separate information for all kinds of characters.
          – Quality assurance of the casing joint installation
          The documentation and quality control for installing casing joints must be digitized.
          The sense and possibility to incorporate the collected digitized data into a GIS system should be investigated for a fully integrated quality system of the casing joint installation.
          – District heating stakeholders should have the possibility to access calculation programs online. Manufacturers of pre-insulated pipes for district energy should offer this service on their website. It should allow the calculation of optimized dimensions of the steel carrier pipe and the insulation series.

        5. Produce products that can transport energy with the lowest possible environmental impact.
          The heat loss of a district heating network causes a considerable CO2 footprint, and it is imperative to focus on its reduction in the network. This can be done in many ways, and choosing the right pipe system is crucial.
          If comparing the heat loss of a single pipe to a double pipe, the choice seems obvious. The below figures show the savings in heat loss for dimensions ø88,9 to ø219,1 series 2 single and double pipe is between 36% – 52%

      Dimension steel ød mm Heat loss single pipe W/m trench Heat loss double pipe W/m trench Savings heat loss W/m trench Savings heat loss in %
      88,9 34,8 22,1 12,7 36
      139,7 42,3 20,5 21,8 52
      219,1 50,2 25,3 24,9 50


          • Flow temperature = 110°C
          • Return temperature = 80°C
          • Soil temperature = 8°C
          • Normal soil conditions
          • Soil covers 800 mm
          • λ50 Values of the PUR foam = 0,025 W/mK (new value)
          • 1% saved kW means saving 1% of the CO2 emission, no matter what fuel is used for the boiler.


        Many relevant aspects must be considered to choose the right pipe network for the next generation. The quality of the pipe system with an optimum service life is essential. A long service life ensures the operating costs and protection of the environment.

        Buying EHP-certified products, ensuring all products fulfill EN13941, buying from an ISO 9001-certified manufacturer, and ensuring a correct static design of the pipe network assures all this.

        In addition to quality, environmental aspects must be taken into account.

        Besides the carbon footprint of the product, the production process and transportation of the feedstock and finished products must be analyzed, as the environmental impact within the production process, such as handling of chemicals and waste.

        For further information please contact: Jens Rasmussen, j.rasmussen@isoplus.dk

        Meet the authors

        Jens Rasmussen
        Technical Manager, Isoplus
        Sabrina Fröhlich
        PR, Head of Marketing, Isoplus
        “How to choose a pipe network for the next generation heating transition” was published in Hot Cool, edition no. 4/2023
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