“Computational Civil Engineering - "Intersections" International Journal

“Computational Civil Engineering 2005”, International SymposiumIaşi, România, May 27, 2005Dynamic thermal behavior of building components.Calculation methodsRodica Rotberg 11 Ph.D., Technical University “Gh. Asachi” IasiSummaryEuropean standard prEN ISO 13786 specifies the characteristics related todynamic thermal behaviour of complete building components and gives methodsfor their calculation, data required, period of thermal variations.The paper presents matrix transfer method for thermal calculus of buildingelements, and examples of applicationKEYWORDS: building, dynamic thermal characteristics, calculation methods1. INTRODUCTIONThe steady-state R value, traditionally used to measure energy performance of abuilding envelope does not accurately reflect the dynamic thermal behaviour of allcomplex building envelope systems. In this way, the effects of thermal inertia areneglected, or, in a better case, are taken into account by means of some correctioncoefficients.Currently, the standard modeling practice is to replace complex materialconfigurations by one dimensional multi-layer structures with similar R values andsimilar material arrangements. Unfortunately, such simplifications cannotaccurately represent the complicated dynamic heat transfer that takes place in manycurrently used wall and roof assemblies.Simplified models were developed based on classical heat transfer theory andresistance-capacitance analogues. The simplified procedures apply only to planecomponents. They are based on the penetration depth of a heat wave calculated forthe material adjacent to the surface.European standard prEN ISO 13786 specifies the characteristics related todynamic thermal behaviour of complete building components and gives methodsfor their calculation, data required, period of thermal variations.