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NC-v4 EAp2:Minimum energy performance

Curtain wall system

Hi all,

We are working on a new building with a curtain wall system and are wondering how we should be modeling the Baseline building fenestration. I presume we should we be going with the curtain wall option of ASHRAE 90.1-2010; however, are the opaque elements included or is it only the glazing element of the fenestration inlcuded in that option? 

Thank you.

Kind regards,

Nikos

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Marcus Sheffer
LEED Fellow
7group / Energy Opportunities
LEEDuser Expert
4454 thumbs up

Thu, 10/15/2020 - 13:59

Opaque elements of a curtain wall system are considered wall, not window. See the definitions in the front of 90.1.

Thu, 10/15/2020 - 14:40

Hi Marcus, According to ASHRAE 90.1-2010 for climate zone 3, the requirement for metal framing (curtainwall) is a U-value of 3.41, correct? What I would like to know is whether this values takes into account the opaque wall elements, as well, or it is only the glazed part which is included? If this value applies to both glazed and opaque wall elements, then am I right to think that we could possibly build the building envelope using an overall U-value of 3.41? Thanks. Kind regards, Nikos
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Marcus Sheffer
LEED Fellow
7group / Energy Opportunities
LEEDuser Expert
4454 thumbs up

Thu, 10/15/2020 - 15:06

Yes that is correct. It does not account for the spandrel panels. Those are considered a wall. Some of the framing would be associated with the windows and some with the walls. So the parts for the curtainwall system with windows would include the frames associated with those windows and would be included in the U-value you mention.

Fri, 10/16/2020 - 09:17

Thanks Marcus - that makes sense indeed.

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