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Heated stadium seating: Sit & Heat devised it, Sirris made it!

In early 2015, when the Dutch SME Sit & Heat contacted Sirris to produce a heated stadium seat, it knocked on the right door. A few years earlier, Sirris had already developed applications for slightly conductive thermoplastic materials. Unlike conventional, fully insulating plastics, an electric current can flow though this type of material. The current meets with resistance, which releases heat. It is the ideal solution for Sit & Heat.
  • A few years ago, Sirris developed a thermoplastic material with an electrically conductive charge.
  • In 2015, Sirris adapted this principle to develop heated stadium seating for Sit & Heat.
  • A stadium in the Netherlands will be the first to be fitted out with a few thousand of these seats.


Sit & Heat develops heated seats and cushions as a comfortable and more eco-friendly solution for terraces and boats, stadiums, caravans, churches and gardens. It is a good example of an SME built around an original idea, dreamt up in 2008 by its founder, Dutchman Jorg Rijkschroeff.


“We had already succeeded in making an electric current flow through plastic. Since plastic is a poor conductor, it heats up.”

Heated, resistant and coloured plastic 

Although the principle of semi-conductive thermoplastic material was already a reality, the optimal composition and form still needed to be determined to ensure that the seats could be heated without being distorted by the heat and/or the supporters’ excitement. The second challenge for Sirris was how to make the seats an attractive colour, since their conductive capacity is linked to the addition of carbon black, which has a fairly unappealing colour.

Co-injection moulding

As with most great ideas, Sirris's solution was a simple one. The seats will be produced through the co-injection moulding of two different materials: a coloured top layer in classical propylene and a heated bottom layer in polypropylene charged with carbon black. As the materials of the two layers are compatible, they will naturally bond during the co-injection moulding, which makes the production process simpler and more practical.

First stadium fitted out in 2016

A prototype developed by Sirris in 2015 showed that the seat quickly reaches the desired temperature in stadium conditions while keeping its solidity. Sit & Heat is now in the process of incorporating the technique into the products of a British stadium seating manufacturer. The first pilot run will be installed in 2016, and the first stadium is expected to be fitted out with a few thousand seats in 2017.