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How to model stairs opening between floors

asked 2017-07-09 07:08:28 -0500

Avi gravatar image

updated 2017-07-09 12:54:55 -0500

Hello I am new to OS trying to model my future house (residential). I was wondering how to model the opening of the stairs between the floors. Reading relevant posts I came to conclusion that I need to mark the place of the opening in the floor/ceiling as air wall, but since the air wall zone mixture measure is not suitable for floors I am not sure how to proceed.

How severe would be the impact of not connecting the different floors?

Avi

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answered 2017-07-10 09:18:48 -0500

Matt Koch gravatar image

If the first floor has a stairwell and the second floor has a stairwell right above that of the first floor, then I tend to model the first and second floors without their stairwells first, each at its own floor height. Then I add a single stairwell with a total height of the first and second floor combined. Surface matching should take care of the rest.

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@Matt Koch, a few things to be aware of if you do this is making sure the lighting for stair tower is properly accounted for as well as its contribution to the building floor area.

David Goldwasser gravatar imageDavid Goldwasser ( 2017-07-10 14:28:03 -0500 )edit

Thanks for pointing that out. I am assuming - perhaps falsely so - that each floor's area (minus its respective stairwell area) is added up to get the total area for the building, and then only one stairwell area is added to that? The same would apply to elevator shafts. Plus, these areas should only be added if the stair well (or elevator shaft) is conditioned? I would love to get an air flow network going, but have not been able to understand how to do that thus far. Presumably, this would take care of the possibly substantial thermal stack effect that could occur in such a stair well?

Matt Koch gravatar imageMatt Koch ( 2017-07-10 14:54:52 -0500 )edit

@Matt Koch, That is a nice workaround. For my house it would create some issues with daylight as my stairwell is placed a long a 5 meter long vitrine on the east faced.

Avi gravatar imageAvi ( 2017-07-11 00:39:45 -0500 )edit
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answered 2017-07-10 06:44:10 -0500

TNZ Energy gravatar image

I suggest running a model with an air wall and a second run without. This will allow you see the relative impact of using the air wall assembly. My guess is that there would be more of an impact if you are using an airflow network than if you are not. Passive air circulation is going to be important to model in this small structure. It would be great to hear from somebody else about how well the air wall works in horizontal surfaces. Eric

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an "Air Wall" in OpenStudio is mainly intended to allow daylight to pass through a zone boundary that doesn't represent a physical wall or floor when using Radiance for daylighting. When exported to EnergyPlus an "Air Wall" has thermal properties somewhat like a piece of plywood. It doesn't introduce any airflow between the two zones. There are a few measures that use air walls and interior operable windows, to add in zone mixing, but the one's I'm aware of are for very specific use cases.

David Goldwasser gravatar imageDavid Goldwasser ( 2017-07-10 14:31:40 -0500 )edit

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Asked: 2017-07-09 03:13:14 -0500

Seen: 704 times

Last updated: Jul 10 '17