[Bldg-sim] Thermal Zones

[Nick Caton]

Hi Attiq,

It's easy to blur how "thermal zoning" should/shouldn't be handled without sufficient context.  Recognize that this term can have slightly different implications/definitions when you are discussing HVAC design, energy modeling, and LEED/90.1 requirements.  Context is critical.

More specifically, there are often multiple right answers to how you can choose to define thermal zones for a given model: rest assured it will be your call to make (and justify) in the end.  I generally start by defining which areas are covered by the different conditioning systems.  Then, if you have multizone systems, divide those floor areas up into zones with respect to the associated system.  One way to think of that is "one zone per thermostat."  These zones may or may not be defined by interior partitions.

Further, if the model's complexity is anticipated to be unwieldy down the road, I'll consider consolidating zones with similar load profiles, occupancy characteristics, & systems (i.e. a series of contiguous private offices along a shared perimeter).  90.1 and the 90.1 User's manual go into more depth in regards to what is considered acceptable.  Also, be mindful of procedural limitations for your energy modeling software/tools of choice when making these zoning simplification decisions - your chosen software may dictate to what extent this even makes sense from a time-efficiency perspective.

Specific to LEED and multi-tenanted buildings, it has been my experience that LEED reviewers will demand the most recent tenant layouts/information at the time of model review be incorporated into the model.  If your present design includes any un-tenanted "shell" space for future tenants, you'd be well advised to plan ahead as you assemble your model for how you might address needing to re-zone parts of the project in the indeterminate future.  Additionally, I have read LEED core & shell includes guidelines for how to address the future loads of such spaces (Equipment, LPD's and so forth), though I believe you can choose to document different figures if there are building performance specs the future tenants are to be held to.
Best of luck!

~Nick
[cid:489575314 at 22072009-0ABB]

NICK CATON, P.E.
SENIOR ENGINEER

Smith & Boucher Engineers
25501 west valley parkway, suite 200
olathe, ks 66061
direct 913.344.0036
fax 913.345.0617
www.smithboucher.com

From: bldg-sim-bounces at lists.onebuilding.org [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of javed iqbal
Sent: Wednesday, February 13, 2013 11:44 AM
To: Attiq Ur Rahman
Cc: bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] Thermal Zones

You should check following link to get better idea on Thermal Zoning.

http://www.bembook.ibpsa.us/index.php?title=Thermal_Zoning_Determination


On Wed, Feb 13, 2013 at 11:25 AM, Attiq Ur Rahman <AUR at cjbrownenergy.com<mailto:AUR at cjbrownenergy.com>> wrote:
I am modeling an office building for LEED which will house different tenants that will consists of a dental clinic and medical clinic etc. There are number of different spaces in the building. Energy Modeling for LEED how many thermal zones do I need to model.


Sincerely,
Attiq ur Rahman


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--

Javed Iqbal, LEED AP, CEA
Energy Analyst
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