Does anyone have the properties for a hollow steel beam ??

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I am trying to create a lofted glass roof held up by hollow steel beams (a nifty atrium in a swimming pool area at a condo complex !!). But I am no information on a hollow steel beam (about 2 x 4). Hollow.
Any suggestions ??
John Aulbach

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Joined: 2011-09-30
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Hi John,

If these structural beams are simply holding up the roof portion of the envelope (as with steel trusses supporting a steel deck, and similar situations), then I would ignore them in the context of an energy model. Their actual contribution to the movement of heat into/out of the space is essentially just adding building mass, equivalent to steel/aluminum benches along the deck.

If these beams however are an integral component to the roof assembly (akin to studs in a wall construction) and their thermal transmission properties are pertinent to how readily heat will conduct through the roof part of the envelope? then you will want to give them special attention. I would assert that in almost any climate, a steel component like this with surfaces exposed to the interior/humid air may be expected to run a high risk of dropping below dewpoint become a condensing surface (source of interior rain), barring impressive ACH, energy-intensive dehumidification, or seeing the pool drained/covered through such conditions.

I might in the latter scenario start with some of the 90.1 appendix A tables covering the detrimental effects of steel studs in walls ? I think those reference some further research that could lead you to a simple 2D heat transfer approach given the details of your full assembly. If the whole atrium/steel assembly is however really complex, you might want to consider a more invested path in performing (or, if it were me, hiring someone) to perform a 3D heat transfer analysis to determine the whole-assembly performance.

Paging @Neal Kruis ? I suspect he might be able to recommend specific software (for a DIY approach) or people/companies (if you?re in a position to hire this out).

Best of luck!


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Nick Caton, P.E., BEMP
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Energy and Sustainability Services
Energy Performance Contracting

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