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LPD Space-by-Space Method v.s. Building Area Method

asked 2019-12-31 14:04:06 -0500

updated 2020-01-19 12:07:35 -0500

Dear all, I have a question regarding LPD space-by-space method v.s LPD building area method. I would like to know if I use the space-by-space method for the baseline model, do I have to use the space-by-space method for the proposed model or it doesn't matter. This means I can use the space-by-space method for the baseline model but use the building area method for the proposed model. Thank you!

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It has been moved

EnergyPlus question gravatar imageEnergyPlus question ( 2020-01-03 09:29:40 -0500 )edit

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answered 2020-01-07 16:06:25 -0500

updated 2020-01-15 17:35:11 -0500

Per ASHRAE 90.1-2016 and ASHRAE 90.1-2019, only space by space method mentioned that can be used for the baseline model. From LEED 4.1 as well. "Baseline: All building spaces area modeled using the Space-by-Space Method. (Previous versions of ASHRAE allowed projects to use the space-by-space or building-area method)" From my understanding it means the proposed model should only use Space-by-Space Method. However, if the lighting neither exists nor is specified, lighting power for the proposed model shall be determined in accordance with the building area method and the baseline model should use the Building Area Method as well.

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This is not true for 90.1-2016. The PNNL manual for the PRM in 90.1-2016 allows both SbS and BAM as long as both the baseline and proposed use the same method.

Luis Lara gravatar imageLuis Lara ( 2020-01-08 13:14:56 -0500 )edit

Thank you for mentioning this reference "https://www.pnnl.gov/main/publications/external/technical_reports/PNNL-26917.pdf". It clarifies "the baseline model should use Space by Space in accordance with Standard 90.1-2016 Table G3.7, except where lighting neither exists nor is submitted with design documents, the lighting classification method shall be the same as proposed." From my understanding, it means only the Space by Space method can be used for the baseline model unless the lighting information is unknown. If it is unknown the baseline building should follow the proposed building.

EnergyPlus question gravatar imageEnergyPlus question ( 2020-01-13 10:45:36 -0500 )edit

Follow the previous comment. I think your comment is correct if only under this condition: If the space types are known, the proposed model has to use the Space by Space method but not the Building Area method for LPD. In this way, the baseline model will always the same as the proposed model. Please correct me if my understanding is wrong.

EnergyPlus question gravatar imageEnergyPlus question ( 2020-01-13 10:53:21 -0500 )edit

I found the certain answer from LEED 4.1 as well. "Baseline: All building spaces area modeled using the Space-by-Space Method. (Previous versions of ASHRAE allowed projects to use the space-by-space or building-area method)"

EnergyPlus question gravatar imageEnergyPlus question ( 2020-01-13 11:05:18 -0500 )edit
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I just attended a webinar by the DOE on changes to Standard 90.1-2019. They clarified that you will always use the space-by-space method in the baseline.

Luis Lara gravatar imageLuis Lara ( 2020-01-23 13:14:17 -0500 )edit
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answered 2020-01-01 20:14:56 -0500

The baseline and proposed models must use the same method per Table G3.1 No. 6. Lighting.

Baseline Building Performance

Lighting power in the baseline building design shall be determined using the same categorization procedure (building area or space-by-space method) and categories as the proposed design with lighting power set equal to the maximum allowed for the corresponding method and category in Section 9.2...

You can use more than one Building Area Method building type for buildings that have distinct areas, such as parking garages.

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What about ASHRAE90.1-2019. Per Table G3.1 No.6, it seems only Space-by-Space method can be used for the baseline model. However, per G 1.2.1 building area or space-by-space method can both be used for the proposed model. Does that mean in ASHRAE 90.1-2019, proposed model can use building area method when the baseline model uses space-by-space method?

EnergyPlus question gravatar imageEnergyPlus question ( 2020-01-02 12:11:17 -0500 )edit

I don't have a copy of 2019, but 2016 G 1.2.1 b. says you can use either Table G3.7 (SbS) or G3.8 (BAM).

MatthewSteen gravatar imageMatthewSteen ( 2020-01-02 12:26:59 -0500 )edit

Yeah, I found this sentence as well, but G1.2.1 only talking about proposed model. If you go 2016 G3.1 No.6, it mentioned only table G3.7 can be used for the baseline model as well. I checked the manual of 2016, it mentioned only table G3.7 for the baseline model. That is why I got confused.

EnergyPlus question gravatar imageEnergyPlus question ( 2020-01-02 12:31:17 -0500 )edit

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Asked: 2019-12-31 14:04:06 -0500

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Last updated: Jan 15