Highly Efficient Hybrid Systems – Wall Heating on Interior Insulation (H-WIHS)

Schematische Darstellung der Funktionsweise von Wandaufbau mit Wandheizung
© Fraunhofer IBP
Bild links: Schematische Darstellung der hygrothermischen Wirkung einer Wandheizung mit Innendämmung an einer Bestandswand montiert. Bild rechts: Schematische Darstellung mit vertikalem Schnitt durch einen Wandaufbau mit Wandheizung auf Innendämmung (H-WIHS) mit Bezeichnung der Bauteilschichten.

When wall heating systems are installed on exterior walls in existing buildings, adding interior insulation is particularly beneficial. It reduces heat loss through the exterior wall and, at the same time, allows a transition to surface heating systems, which offer enhanced thermal comfort, lower flow temperatures, and better integration with renewable energy sources. This combination is best approached as a comprehensive, highly energy-efficient Wall Heating-Interior Insulation Hybrid System (H-WIHS). To realize this concept, 10 manufacturing companies and 2 trade associations are working in close collaboration with Fraunhofer IBP in a project funded by the German Federal Ministry for Economic Affairs and Climate Action (BMWK). The implementation of six real-world test areas at the Fraunhofer Center in Benediktbeuern enables a broad-based study and demonstration aimed at knowledge transfer.

Project goals

The goal is to combine the benefits of interior insulation and wall heating into a single high-performance retrofit solution for existing buildings as highly energy-efficient wall heating-interior insulation hybrid systems (H-WIHS).

To overcome current limitations of the non-verifiable or simplified verification methods for improved thermal insulation with H-WIHS, the project conducts systematic scientific investigations into the drying potential of wall heating applied to interior insulation systems. Different H-WIHS combinations are being implemented at the Fraunhofer Center in Benediktbeuern and examined under real-world conditions in the lab test stand of the MEGA platform (Modular Platform for Energy-Efficient Building Services). The resulting data serves as a foundation for computational studies and demonstration-based training.

Project status

The systems are currently being installed and commissioned in the historic Alte Schäfflerei building at the Benediktbeuern Monastery. On the ground floor, an H-WIHS in a drywall configuration has been implemented (Figure 1). At the MEGA platform, preparations for lab testing have been completed (Figure 2).

Einbau der Innendämmung aus Kalziumsilikat-Platten
© Fraunhofer IBP
Bild 1: Im linken Bild ist die originale Wandoberfläche mit den Messsensoren zur Messung von Temperatur, Feuchte und Wärmefluss auf zwei Wandhöhen erkennbar. Einige Wochen später wurden die Innendämmung aus Kalziumsilikat-Platten sowie die Wandheizrohre aus Kupfer bereits aufgebracht.
drei Testflächen im Laborprüfstand der MEGA-Plattform
© Fraunhofer IBP
Bild 2: Im Laborprüfstand der MEGA-Plattform befinden sich drei Testflächen aus Holzfaserdämmung (links), Mineralschaumplatten (Mitte) und Kalziumsilikat-Platten (rechts) kurz vor der Fertigstellung.

Project partners

  • Cooperation Partners
  • ArgillaTherm GmbH
  • Clina Heiz- und Kühlelemente GmbH
  • Etex Group
  • HASIT Trockenmörtel GmbH
  • St. Gobain GmbH G+H AG
  • Knauf Gips KG
  • naturbo Lehmputz-Trockenbausysteme GmbH & Co. KG
  • Schütz GmbH & Co.KGaA

Component Suppliers

  • Typha Technik Naturbaustoffe
  • VIEGA GmbH & Co.KG

Professional associations

  • Federal Association of German Heating Manufacturers (BDH)
  • Interior Insulation Trade Association (FVID)