U-Value of a ventilated façade

Alles zu DELPHIN, dem Programm zur hygrothermischen Bauteilsimulation.

Moderatoren: ghorwin, fechner, ruisinger

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Haalsaad
Beiträge: 15
Registriert: Mi 25. Mär 2020, 15:55

U-Value of a ventilated façade

Beitrag von Haalsaad » Do 2. Apr 2020, 13:26

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: 35
Registriert: Mi 19. Dez 2018, 08:32

Re: U-Value of a ventilated façade

Beitrag von fechner » Do 2. Apr 2020, 13:49

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: 15
Registriert: Mi 25. Mär 2020, 15:55

Re: U-Value of a ventilated façade

Beitrag von Haalsaad » Do 2. Apr 2020, 16:00

Thank you very much!

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