Development of heat economy and construction of facade elements

Juhani Olin, Juha Ratvio, Jukka Jokela

Research output: Book/ReportReport

1 Citation (Scopus)


The research project is based on energy-saving efforts, which for their part can be carried through reducing e.g. thermal losses through the wall. The need for developing the facade elements was created, moreover, by changes in the house building sector, with a shift in emphasis on small house construction and with requirements for more attractive outward appearance. This research tends to examine the wall structure as an independent structural entity by studying the possibility of developing the wall structure and means of making it competitive. An improved heat economy will also cause changes in other properties of the wall. The properties of the most commonly used insulating materials such as mineral wool, polystyrene and polyurethane, and their possible use as insulation in concrete facade elements are also studied. Along with the traditional mineral wool insulation, the plastics insulation make new applications possible in certain areas, for example, in cases where the thickness of the concrete wythe and the number of wall ties can be reduced by turning to advantage the strength of plastics insulating materials. The interaction between the concrete wythes influences the carrying capacity of the load-bearing facade element. Depending on the wall ties, the interaction between the wythes can be complete, partial or nil. The best carrying capacity is attainable with a complete interaction, which is produced e.g. by the diagonal truss reinforcement used as wall ties. The diagonal reinforcement induces, however, cold bridges and indirect forces between the wythes. Therefore more flexible anchoring methods are recommended when the sufficient carrying capacity is achieved by them. The purpose of anchoring between the inner and outer concrete layer of the non-bearing element is generally to suspend only the outer layer from the inner layer. It is then advisable to try to arrange the anchoring as flexible as possible, in which case the indirect forces, as well as cracks and deflections induced through these forces can be avoided. The outer layer can also be suspended either partially or completely by means of plastics insulation, when the strength and deformation capacity of the bond between the insulation and the concrete, and those of the insulation, together with the long-term durability of anchoring are ensured. The carrying capacity of the element and the size of the indirect forces due to temperature differences with different types of truss reinforcement were evaluated by means of computer calculations. The strength of truss reinforcement was examined further in laboratory tests, in which the outer wythe of the element was loaded. The external concrete wall is basically of compact structure, but with regard to the heat economy and moisture conditions of the structure it is important that the joints and seams are also tight. On the other hand, by ventilating heat insulation care is taken that the moisture in the structure can escape outdoors. Instructions for design, manufacture and assembly are given in the report, by means of which these requirements can be fulfilled. The development of manufacturing techniques is possible by applying prestressing and sliding form construction techniques, fibre concrete and vacuum concrete techniques, together with the sprayed insulating materials and pastes. The above methods require, however, that standardized products and large manufacturing series are used. In the report, a number of ideas of developing the concrete facade element are proposed. Most favourably judged were: the prestressed wall element of sliding-form construction, the element based on the bearing capacity of plastics insulation and connecting pins, and the element provided with the concentrated anchoring. Bearing capacity, manufacturing techniques and costs of new structures are also discussed.
Original languageEnglish
Place of PublicationEspoo
PublisherVTT Technical Research Centre of Finland
Number of pages166
ISBN (Print)951-38-1953-1
Publication statusPublished - 1984
MoE publication typeD4 Published development or research report or study

Publication series

SeriesValtion teknillinen tutkimuskeskus. Tutkimuksia - Research Reports


  • concrete
  • sandwich structures
  • elements
  • walls
  • facades
  • heat economy


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