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Thick wall partly penetrating a zone

asked 2016-11-04 12:16:39 -0500

Aryan Shahabian's avatar

updated 2016-11-04 13:10:35 -0500

Dear All,

A thick wall passes through a wall of a zone (please see the image below). thick wall partly penetrating a zone

Is it possible to define it in EnergyPlus, taking into account its shading effect as well as its thermal interaction with the zone ? (Please take into account: 1- it is not an exterior shading device with thermal break. It is a continuous wall with significant heat transmittance. 2- The walls of the room include large windows, therefore the inner part of the penetrating wall also recieves sun.)

The only way I could imagine to define the thick wall, is to divide it into two parts (interior and exterior), and then define each part as a zone! So 2 new zones would represent the wall. But these zones won't have any cavity or air inside; because the wall is solid. then the question would be:

What is the minimum size of a zone? Could a zone be as thick as a wall (e.g. 50 cm width)?

What is the maximum thickness of a wall/floor/ceiling/etc. in a zone? Could they occupy the whole space of the zone? i.e. Could a wall have a width equivalent to half of the whole zone's width?

I asked the same question in HoneyBee Grasshopper page. Somebody suggested me to divide the mass into an InternalMass and a ContextSrf. But then there would be 2 problems:

1- It's not possible to assign an E+ construction material to the outer part of the mass (ContextSrf). Therefore its surface temperature would remain the same as the weather around.

2- The internal mass won't be affected by the sun. It also won't thermally interact with the outer part of the mass. Take into account that in reality there is no thermal break between the interior and the exterior parts of the mass. It is a single continuous concrete wall.

Actually I sent the same question in EnergyPlus helpdesk but still haven't received any answers. I would appreciate if you could reply to my question.

Best, Aryan

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Good question, while this particular configuration looks unique if you turn it sideways it's not too different from more typical situation of exterior balcony that isn't thermally broken from the slab. Which is also challenging to model because of thermal-bridge

David Goldwasser's avatar David Goldwasser  ( 2016-11-04 16:28:04 -0500 )edit

Hi David, Many thanks for your reply. I read some posts about thermal-bridge and simulating it using THERM. Still I have a question: Is it possible to define a thermal bridge as a "zone" in EnergyPlus? For instance if there is a balcony with no thermal break.. If the the height of the balcony is 40cm, then define a zone in which the width of its floor and ceiling are 20cm. Could it work out fine? Thanks again

Aryan Shahabian's avatar Aryan Shahabian  ( 2016-11-06 09:23:12 -0500 )edit

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answered 2016-11-04 13:07:03 -0500

Ricardo GAllegos's avatar

updated 2016-11-04 13:43:50 -0500

I think you could split the indoor zone into two zones, divided in the middle by two walls. 1) The thick wall, 2) An air wall.

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Thanks for your reply. Then the problem would be: The external part of the wall won't thermally interact with the internal one

Aryan Shahabian's avatar Aryan Shahabian  ( 2016-11-04 14:58:13 -0500 )edit

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Asked: 2016-11-04 12:16:39 -0500

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Last updated: Nov 04 '16