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Multi-Family Baseline Model

asked 2019-11-13 13:15:20 -0500

updated 2020-01-19 12:09:42 -0500

Dear all, I have a question regarding how to simulate the baseline fenestration U-value for the multifamily project. When I read ASHRAE 90.1-2013 Appendix G Table G3.1.5, no clear explanation has been found. So the baseline fenestration type will be assumed the same as the proposed building when I do the appendix G model. However, when I read the LEED guideline for multifamily projects, it mentioned "When the proposed design is a wood-framed building, fenestration in the baseline design shall be based on prescriptive requirements for vertical glazing with nonmetal framing within Std. 90.1-2010 Table 5.5. When the proposed design is a non-wood-framed building, fenestration in the baseline design shall be based on prescriptive requirements for vertical glazing with metal framing within Std. 90.1-2010 Table 5.5.".

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answered 2019-11-13 15:58:11 -0500

bbrannon4 gravatar image

I think you may be missing a section in 90.1. It pretty clearly defines what envelope constructions to use. I don't see a table G3.1.11, but if you look in the main table G3.1 No. 5 Building Envelope, in the Baseline portion under Vertical Fenestration Assemblies, it directly references the tables is Section 5 (Table 5.5-1 - 5.5-8). In these tables you can look up your climate zone and then since you are doing a multi-family building, use the Residential column.

So the LEED guideline is correct, and this is also written directly in 90.1. In general, no constructions should be modeled int he baseline as identical to the proposed unless it's an existing and unaltered facade portion.

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Thank you, yes I intended to reference G3.1 No. 5 Building Envelope but put the wrong number. I agree with you that G3.1.5 references table 5.5-1 to 5.5-8. However, there are different fenestration types in these tables (eg. Nonmental framing, all, metal framing, fixed and so on). My question is how do I decide which type of fenestration should be used. LEED mentioned it depends on the proposed building construction, I assume it means the proposed wall construction type will be used to decide the fenestration type for the baseline model.

EnergyPlus question gravatar image EnergyPlus question  ( 2019-11-14 13:29:31 -0500 )edit

Yes, it depends on the proposed construction framing, but this is about glazing, so the proposed wall construction doesn't matter. If your proposed window assembly is non metal (such as wood, vinyl, fiberglass, etc), then you have only one option to pick, but if it is metal (which is much more common, especially if you have a curtain wall or something), then you chose based on if they are operable or not.

bbrannon4 gravatar image bbrannon4  ( 2019-11-14 13:54:27 -0500 )edit

I see, I think this is the method I used previously. But the way LEED Guideline wording it sounds like wall to me at first. Thank you for clarifying about it.

EnergyPlus question gravatar image EnergyPlus question  ( 2019-11-14 16:09:53 -0500 )edit

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Asked: 2019-11-13 13:15:20 -0500

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Last updated: Nov 14 '19