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NC-v4 EAp2:Minimum energy performance

Lighting Building Area Method Takeoff Clarification

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RDK E&S
Energy Engineer / Sustainability Specialist
NV5
LEEDuser Basic Member
15 thumbs up

Hi, 

I'm working on a project and am using the Building Area Method for Lighting in the Baseline and Proposed; this large manufacturing facility has a significant amount of Warehouse space (25% of building area). I'm looking for guidance for a few details: 

  1. I saw on another post the using more than 1 building types for the Baseline's lighting is acceptable. For this project, I'm considering using the "Manufacturing facility" and "Warehouse" building types from Table 9.5.1. I didn't see any language in ASHRAE 90.1-2010 about acceptability of using more than 1 building type. Does anyone know where this indicated in the Code? Or is simply industry best practice?
  2. I am hoping to save time with takeoffs and use a Comcheck to get a building wide LPD. However, the ComCheck will provide a single building LPD (total interior wattage/total area), and won't have distinct LPDs for the "Manufacturing facility" and "Warehouse" building areas used for the Baseline. Is it acceptable to use 2 Building Areas in the Baseline while using a single, overall building LPD applied to the whole building in the Proposed? I understand using two distinct LPD's will certainly be more accurate, but will incur significantly more time during model pre-processing. 
  3. I am breaking out the Warehouse and Manufacturing facility building areas separately as there is a significant difference in LPD to avoid LEED comments. However, it would certainly help our savings if were allowed to use the "Manufacturing facility" for the entire building. Does anyone know if the "Manufacturing facility" Building Area includes a significant amount of Warehouse space in the calculations? My initial reaction is that some Warehouse area is included in that average, but I'm looking for feedback. 
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Michael Brown
Energy Analyst & Energy Systems Design Engineer
HKS
LEEDuser Expert
7 thumbs up

Wed, 09/25/2019 - 22:17

I believe your referring to this post correct? https://leeduser.buildinggreen.com/forum/building-area-method-interior-lpd This post on Energy Models.com my be useful (its a LONG feed, so I've summarized below) http://energy-models.com/forum/energy-modeling-software/equest/leed-title-24-ashrae-901/building-area-method-ashrae-901 There will be a small time savings in Baseline model creation by not determining and entering space-by-space power usage into the model. 90.1's wording about "...if a lighting design exists..." points me towards space-by-space if at all possible. But GBCI seems to accept both, regardless of possible Building Area Method inaccuracies which as Nick pointed out may or may not be significant. 1. Use the same method in both cases. 2. Several people think 90.1 suggests space-by-space if the lighting system is designed. a. Not always (ever?) enforced/requested by GBCI. b. When the model is being used to inform the design or calculate incentives, this is the more accurate approach if there is variance in the spaces for control types, LPD values, and occupancy schedules. 3. Although Building Area Method may not provide the most accurate predictions of energy usage, it may still be "legal" for EAC1 point calculation purposes.
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RDK E&S
Energy Engineer / Sustainability Specialist
NV5
LEEDuser Basic Member
15 thumbs up

Thu, 09/26/2019 - 17:38

Hi Michael,  I appreciate your time in responding my post, but I'm a bit confused. I'm still looking for clarification from ASHRAE 90.1-2010 specifically to address #1. I'm confident I can use the Building-Area-Method per ASHRAE 90.1 2010 9.2.1, and Appendix G clearly indicates that Building area method is fine per "Lighting power ... shall be determined using the same categorization procedure (building area... method) and categories as the proposed design...". 
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Waleed AlGhamdi
Sustainability Enabler
Eskew+Dumez+Ripple
LEEDuser Basic Member
20 thumbs up

Mon, 09/30/2019 - 15:26

Short answer: you're allowed. From ASHRAE 90.1 2010 User Manual, page 9-31:  "... The Building Area Method is the easiest way of determining the interior lighting power allowance of an entire building or an entire occupancy in a multi‑occupancy building." "... If a single permit application includes the lighting systems for more than one occupancy, you can make trade‑offs between the occupancies but only if both occupancies use the same method to determine the lighting power allowance. If one occupancy uses the Building Area Method, then trade-offs are not allowed." The caveat: use Building Area Method for all occupancies. 
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Waleed AlGhamdi
Sustainability Enabler
Eskew+Dumez+Ripple
LEEDuser Basic Member
20 thumbs up

Mon, 09/30/2019 - 15:45

Also, many ambiguities of the code are better explained in the User Manual doc. I highly recommend it when in doubt.
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Marcus Sheffer
LEED Fellow
7group / Energy Opportunities
LEEDuser Expert
4454 thumbs up

Tue, 10/01/2019 - 21:06

1. LEED projects have been allowed to use more than one BAM space type in the same project if there is a clear delineation between the two (or more) space types. 2. I do not think that this approach would be accepted. 3. You would likely be asked to separate the areas.

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