Dynamic Simulations for Inhomogeneous Components

For highly inhomogeneous components (windows, doors, etc...), imposing sinusoidal temperatures from one side and constant temperature to the other side, could give periodic thermal transmittance exactly with the same definition described in the standard EN 13786. For thermal bridges something similar to the ψ value of steady-state conditions could be defined: the idea is that a homogenous wall as its own periodic thermal transmittance; when a thermal bridge is applied to this wall (for instance with the insertion of a pillar), the simulation will give a new periodic thermal transmittance. The difference between the two periodic thermal transmittances gives information on the effect of the thermal bridge, obtaining something similar to the ψ value. With a Computational Fluid Dynamic analysis, the paper deals with the definition of linear periodic thermal transmittance that could be useful for the response of the whole building envelope (in terms of complex heat flow rate through the inner environment) to the external temperature oscillation. This approach opens the way to define a new Standard to include thermal bridges and inhomogeneous components in general in the dynamic calculations of the buildings envelope.