LEED Core & Shell questions

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1. Should Tenant Spaces in LEED Core & Shell projects be modeled with Appendix G systems for the Baseline, and for the Proposed as well if there is no HVAC design?
-OR- Should Tenant Spaces be modeled as "unconditioned" in both the Baseline and Proposed? (-OR- some other option?)

2. What is the intent/purpose of the requirement to model separate electric meters for lighting, plug loads and process loads in the Tenant Spaces? Should the cost from these meters be removed from the building energy cost for EAc1 savings?

3. IF HVAC systems are modeled in the Tenant Spaces, should this energy be assigned to separate meters as well?

LEED Core & Shell Appendix 2 describes how the HVAC systems should be modeled for the Core and Shell Building, but not for the Tenant Spaces. Appendix 2 also describes the requirement for modeling separate meters.

Thank you,

William Bishop, PE, BEMP, BEAP, LEED AP

Bill Bishop's picture
Joined: 2012-02-25
Reputation: 7


On the last? C&S I did, LEED wanted Apprndix G systems for the baseline and proposed in the tenant spaces.? They are looking for a perimeter system to condition each exposure and a core unit.? 5 units per floor for a small building was required.

I don't know the intent of the separate meters.? I did assign a tenant meter and attached all the plug loads and HVAC equipment for those spaces to it.

Paul Diglio

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Joined: 2011-09-30
Reputation: 400

See below

Anthony Hardman, PE, LEED AP BD&C

Anthony Hardman, PE
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Joined: 2011-09-30
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i don't recall the page in the leed 3 manual right off hand but 1)
tenant spaces can be modeled as proposed type (hvac/water/lighting) if
there is a legally binding signed/or master lease agreement specifying
the proposed requirements that all tenants must adhere to and said lease
agreement is uploaded as part of the project documentation. i.e. lower
lighting lpd, increased hvac unit efficiencies/power, and water saving

and 2) there is an equest limit on the number of submeters a project
can have, and a core/shell project requires submeters for each tenant to
be separated out between process, lighting, and hvac, so the number of
meters can add up quickly if you're dealing with a sizeable core/shell
with many tenant spaces.

Patrick J. O'Leary, Jr.'s picture
Joined: 2011-09-30
Reputation: 200

Anthony, Patrick, Bill and the list,

I too have a keen interest in answering the question below (which might only be answered by USGBC):

Per the C&S Appendix 2 guidance (reference noted in Bill's original question below),

* "The core and shell building is defined as the parts of the building that are not tenant space. Any constraints or guidance issued to the tenant, such as a maximum level of lighting density or restrictions on occupancy type, must be outlined in the tenant lease or sales agreement (see Appendix 4)."

* "Model the heating, ventilation, and air-conditioning (HVAC) system as described in the design documents. If the HVAC system is not yet designed, use the same HVAC system as the baseline model, per ANSI/ASHRAE/IESNA Standard 90.1-2007, Table G3.1.1A."

* "If the team is pursuing any additional energy-saving opportunities not associated with the core and shell areas, outline the opportunities or requirements in the tenant lease or sales agreement (see Appendix 4)."

And Appendix 4 (http://www.usgbc.org/resources/appendix-4-tenant-lease-or-sales-agreement ),

* "Compliance through a binding tenant lease or sales agreement can be pursued as an alternative to or in conjunction with the standard approach to LEED for Core & Shell credit documentation. Clearly identify which components of the credit will be implemented as part of the developer's scope of work, and which portions will be part of the tenants' scope of work and enforced through binding tenant lease or sales agreements."

Per guidance above, for spaces not yet designed ASHRAE Baseline is to be presumed, unless specific measures are designed in that enhance the baseline approach. If those measures are in the C&S design intended for tenant use, then they must be included in any binding lease agreement material (such as sales information or design guideline/specification).

What is not clear is if the building approach for tenant fit-out defines a tenant design approach which is different from the baseline. Does anyone have experience with being required to show that the defined approach also performs?


David Ellis

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Joined: 2011-10-02
Reputation: 0

what do you mean by "if the building approach for tenant fit-out defines
a tenant design approach which is different from the baseline..." ?

for leed purposes if the building approach for tenant fit-out is NOT
leed compliant per the appendix 4 quote below (or CS grey box at top of
page 274 of the 2009 edition of the leed reference guide) then the 90.1
baseline must be used in both proposed and baseline.

either the design approach is different from the baseline and complies
with the requirements mentioned (appendix 4/page 274 of 2009 edition) or
it is not & the baseline must be used in both the proposed and baseline
simulations (no savings claimed by whatever is actually in the design
approach that does not meet the leed requirements for sale/lease

my edition of the 2009 edition, page 274, CS grey box title is: Credit
for Tenant-implement Efficiency Measures. it is in the eac1 section,
right after the large requirement table in section 6. calculations.

Patrick J. O'Leary, Jr.'s picture
Joined: 2011-09-30
Reputation: 200

If the shell space is not yet fully designed, the understood guidance is that the ASHRAE baseline system is to be used for the shell spaces. My question is if the shell space intended design approach is evident (by system infrastructure installed to support future tenants) via lease documents, has anyone been required to prove the intended system approach performance as well?


David Ellis

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Joined: 2011-10-02
Reputation: 0

maybe we're not clear on what you're asking. it sounds like you are
asking if anyone has been required to prove system performance for a
cs/tenant improvement after the initial project is complete and a tenant
has moved in and may (or may not) have made changes? answer is no, from
me anyway. at least not until all projects are required to go the
existing building (EB)/ongoing maintenance leed route. or if someone
has a project that was CS & then went EB afterwards.

if you're asking a general approach to submittal question then
(historically) if the shell space is not yet fully designed but the
sale/lease agreement requirements are in force (i.e. have been signed,
or master agreement actually uploaded) then energy savings can be
claimed based on requirements in said sale/lease agreement.

did this on one CS project several years ago. the only proof required
to justify the higher efficiency/lower lpd/building elements was the
master sale/lease agreement that included said requirements for hvac,
plumbing, elecrical, and building envelope (if modifications were made).

Patrick J. O'Leary, Jr.'s picture
Joined: 2011-09-30
Reputation: 200

I have a specific application related to the questions posed by David.

Proposed System - We have a core and shell project that includes a central
CHW and HW plant as well as a dedicated outdoor air unit (with energy
recovery). The design intent is to support tenant installation of fan coil
units with outside air ducted to the spaces from the DOAS unit.

Baseline System - Based on the building size the baseline system is System 7
- VAV with reheat.


1. What should be modeled as the tenant HVAC system in the proposed
model? One approach is to use fan coil units to align with the design
intent. But, this thread has recommended using the Appendix G baseline for
the tenant space, which in our case would be System 7 - VAV with reheat.

2. If we model fan coil units, should we follow appendix G specifics
for fan power and other operating parameters despite the fact that fan coil
units are not specifically an option in Appendix G?

3. I believe the tenant design is complete (or nearly complete) with
fan coil units. Should we make use of the tenant drawings to model the HVAC
system? (The tenant design is under a separate contract.)



Mickey Bush, PE, LEED AP

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Joined: 2011-09-30
Reputation: 0

I've been on several proven provider calls where this has been discussed
with GBCI, and in general, their feeling is:

1) If there are no tenant drawings available, even if the design
*intent* is FCUs with high efficiency ECM motors (or something to that
effect), unless the core and shell scope actually shows specification
and installation of the FCUs, the proposed model should use App G

2) If there are tenant drawings available (particularly if they happen
to cover a large portion of the CS building), then GBCI is OK using your
proposed systems in the proposed model.

However, in all of our projects that have gone thru the proven provider
program, all of them were Core and Shell projects with proposed central
chilled water systems, floor-by-floor VAV AHUs, and future tenant VAV
boxes. In this case, we were designing everything except for the VAV
boxes, so it was really only a question of whether we had to use
parallel FP terminals with 0.33 W / cfm (App G), or if we could use our
design intent which was series VAV low temp FP terminals with higher
efficiency motors.

In your case, you don't have an air distribution system designed, so it
is probably a little more complicated. Your tenants could install
anything from FCUs to VAV AHUS with VAV boxes.

If you have a complete set of tenant drawings, or you require tenants to
use a specific HVAC system via a legally binding lease, then you will
probably be OK using your design intent for the proposed model (YMMV).

You should definitely document this for EAp2/EAc1.

James Hansen, P.E., LEED AP

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Joined: 2011-09-30
Reputation: 200