Double skin - Solar reflection and natural ventilation

Advanced 3D solar analysis for a building and its site.
ClementP
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Joined: Fri Nov 28, 2014 1:53 pm

Double skin - Solar reflection and natural ventilation

Postby ClementP » Fri Nov 28, 2014 4:08 pm

Hi,

I am trying to simulated the thermal reaction of double skin.
The structure is define as a room with an external simple glazing/45cm of air (in the room)/internal double glazing. The external glazing have some very narrow opening to allow natural ventilation.

Image

The aim of my study is to observe the rise of temperature during mid-season and summer. The main issues are sun and natural ventilation.

Concerning the sun, I read the "calculation method (apache sim)" and extract several points of interest :

- Solar tracking : Allows the sun ray to go into the room beyond the one in contact with the exterior (p.25)

- Solar ray distribution : When the ray is going throw transparent surface, it is divided in 3 resultants : absorb, transmit and reflect (p.26). Solar factor are applying for internal glazing and even the rays who leave the room are transmit as diffuse in the adjacent room (so it returns to my double skin).

- Diffuse ray distribution : radiation transmit to transparent surface is (like external radiation) divided in the same 3 resultants. This process occur up to 10 times.

Here is my comprehension of the phenomenon :

Image

Is that right? If yes, I miss an information : How much iteration is there for external solar radiation ? The user guide speaks of 10 for diffuse but does not mention the case of direct ray.


Regarding the natural ventilation, I wondering if the "thermal draw" of air is simulated for differents opening (up and down) in the same surface. Here is an example :

Image

The tight glaze represent the hole and have a continuisly open profil in MACROFLOW.

Thanks for you response,
Clément Prévost

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