LEED EA comments about Model Area and the architecture GFA

9 posts / 0 new
Last post

Dear All friends,

I got a LEED EA Cr1 review comment from GBCI.
It's about the model area and architecture Gross square footage. The total building area in the simulation report is 1,121,319.6 square feet and the area in architecture documents is 1,161,727.32 square feet. The comments said that the area value in the model should be consistent with all other credits and LEED online and/or provide a supplemental narrative explaining the discrepancy.

As a energy modeller I think all of you know that the area in the model could not be easily consistent with the architecture CAD drawings. Although In the footprint drawing stage I was very care about each floor' area(because I understand the area in the model should be consistent with CAD drawings especially when it was for a LEED model), it still results discrepancy in the two area values.

Now the difference about the two area values is about 40407.4 sqft (3754sqm), and it is only 3% of the total area. It's hard to revise the model in this stage, but what I should do to explain the discrepancy. Does anybody here have experience to deal with this problem? And do you know how much difference (%) could be accepted by the review team?

Thanks for your attention.

Jie Zhang

Jenny Zhang's picture
Offline
Joined: 2011-09-30
Reputation: 0

is your building single story or multiple story? 40,000 sf is a huge
difference. two things i would check first are:

1. are parts of the building, in the architectural square footage,
exterior? i.e the 1st floor plan sf the architect is using has canopy
area, or is there a walkway under part(s) of the building if it is
multistory?

where did the architect get the sf number they are using? and how does
it impact calculations in other points?

2. does part of the building have plenums? plenum zones in the sv-a
reports will show up in the area sf so if you have a vertical building &
some floors have plenums while others don't this can skew the sf on the
sv-a reports though not on the sf reported as the building/floor
footprints.

Patrick J. O'Leary, Jr.'s picture
Joined: 2011-09-30
Reputation: 0

Patrick,
Thanks very much for your quick reply.
It is a 4-floors retail podium and about 27 floors office tower. Also has a big basement, the total gross floor area is about 1121319 sqft. 40,000sf is a big value but a small percentage for my building.
No plenum zones in our models and I think the area discrepancy is because the outlines of our models? footprint is not the same as the architecture drawings. I have done some simplifies when building the geometry.

I will check according to your reminders. It would be lucky if some outdoor areas is in architecture gross floor areas.

Do you know how small the difference could be accepted by the review team?

Regards

Jie

Jenny Zhang's picture
Offline
Joined: 2011-09-30
Reputation: 0

Hi Jenny,

We have had this issue before as well, there is a box on EAp2 / EAc1 (sorry I never remember which until I am in the form) where you can tick to say your energy model has a different floor area from the architecture plans. This seems to work, you can then write a narrative in response to the comments explaining why.

The second thing that LEED seem to look for is that the floor area is consistent across credits. I think that the tick box in EAp2 / EAc1 negates the need for that but it is worth checking with the other LEED credits to see if you can align with them.

I don?t know how helpful that is but I thought it might be worth mentioning.

Good luck

Annie

Dr. A. Marston, Ph.D. LEED(r) AP BEMP

Annie Marston's picture
Offline
Joined: 2011-10-02
Reputation: 0

Jenny:

Per the attached Advanced Energy Modeling for LEED V2-1, which is available for
free download from LEED On-line, page 30, it states that a 10% variance for
built up areas is allowed.

I have submitted projects to LEED with a 3% or greater deviance and have not had
a problem. We can only trace the CAD drawings and if they are not to scale or
if the design team does not include all wall thickness in the gross square foot
area, the model and design areas may vary.

Paul Diglio, CEM, CBCP

Paul Diglio's picture
Offline
Joined: 2011-09-30
Reputation: 400

You should be fine if you enter the value here:

[cid:image003.png at 01CE1597.B558BE20]

Vikram Sami, LEED AP BD+C

Sami, Vikram's picture
Offline
Joined: 2011-09-30
Reputation: -1

Ouch.

I have had these comments before. They want them to match. The easiest
thing would be for the Architect to change their numbers, but they are
not going to like that.

Have you identified a particular area that doesn't match? It may be
only 3%, and you could argue that, but the ANSI standard for building
area that we are asked to use for homes says within 1 sq. ft. and that's
way less than one percent.

I'd say it's worth submitting the question to USGBC.

Actually, 40,000 sq. ft. shouldn't be hard to find... Where is it?

Robert Wichert P.Eng. LEED AP BD&C

RobertWichert's picture
Offline
Joined: 2011-10-02
Reputation: 201

When you traced the outline of the building, did you use the exterior face? If you used the centerline or inside face you could easily be missing that much space in a large building. eQuest doesn?t assign a thickness to exterior walls in its area calculations and we have made the argument that our number was representative of the conditioned area before when we had small discrepancies.

Brendan Hall

Hall, Brendan's picture
Offline
Joined: 2011-09-30
Reputation: 1

This post is very interesting. Thanks for sharing.

mayweather vs maidana tickets

gumi's picture
Offline
Joined: 2014-04-17
Reputation: 0