In the simple ISO 9164 calculation procedure for transmission heat loss coefficient, HT, it is unclear, and undefined for floor or roof-wall sections, how the parameters in the equations will be calculated. In this paper, a method is proposed for the calculation of ISO 9164 parameters for roof-wall sections. The results obtained by the proposed method for typical roof sections are compared with those obtained by the EN 832/EN 13789/EN ISO 14683 methods and with the L2D values from 2D analysis. A comparison of the floor and roof behaviour is realized using the results of the present and the previous works of the authors. The HT values obtained by the proposed model using the sum of qy through the beam are harmonised with the L2D for floors, which are significantly different from the L2D for roofs with parapet. The results indicate that the L2D values cited in EN 10211-1 are sensitive to the 2D heat flows for floor sections. However, the L2D is not sufficiently sensitive to heat flow from the beam to the parapet and the interactions between the zones within the beam section, whereas the proposed method is more sensitive to the 2D heat flows.
Key words: Thermal bridges, 2D thermal analysis, heat loss, heat transmittance coefficient, thermal analysis.
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