U-Value of a ventilated façade

Alles zu DELPHIN, dem Programm zur hygrothermischen Bauteilsimulation.

Moderatoren: ghorwin, fechner, ruisinger

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Haalsaad
Beiträge: 19
Registriert: 25 Mär 2020, 16:55

U-Value of a ventilated façade

Beitrag von Haalsaad »

Dear Delphin-Team,

I am simulating a highly-ventilated facade (wall + ventilated air gap + cladding). I want to calculate the U-Value of the facade from the temperature difference and the heat flux through the construction (1D simulation). Which approach is the correct one to create a TotalFluxHeat output?

a. [Single] at the interior surface (Boundary flux)
b. [Single] at the first element adjacent to the interior air
c. [Mean] at the whole construction (Field flux)

Follow up question: I am using an [AirChange] and a [LongWaveRadiation] sources to simulate the highly-ventilated façade. From the above listed options, if I was to use option (c) and extract the mean value of heat flux from all the elements, should I export the heat flux from the whole construction (wall + ventilated air gap + cladding), or should I only select the elements of the wall and ignore the air gap and the cladding? Thank you very much for your help!
fechner
Beiträge: 90
Registriert: 19 Dez 2018, 09:32

Re: U-Value of a ventilated façade

Beitrag von fechner »

Hello,

Normally a) is ok. For a 1D construction 'Single' is Ok. For 2D you have to use 'Mean'.

Method c) makes no sense for my point of view. A U-value should reflect the heat losses of a room through a wall. A heat loss means a loss from the room air. This leads to the fact that you have to use the heat flow over the inner boundary.
Haalsaad
Beiträge: 19
Registriert: 25 Mär 2020, 16:55

Re: U-Value of a ventilated façade

Beitrag von Haalsaad »

Thank you very much!
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