[Equest-users] Thermal Blocks

[Nick Caton]

Hi Jeff!

 

It sounds like it's simply a quantity of systems issue then.  

 

90.1 & LEED reviewers would have you use one system per "thermal block"
for packaged baseline systems (#1-4).  I like Bill's clarification, and
agree "thermal block" (90.1's term) is too fuzzy in the context of an
eQuest project, so I'll continue using eQuest terminology.  

 

Re-worded specifically for eQuest:  I'd generally expect each baseline
system to have either a single zone, or a "floor-level" zone & its
corresponding plenum zone, if I were looking over your shoulder at the
HVAC component tree.  You probably shouldn't have any more zones than
that grouped under any one baseline system.  

 

The SV-A reports list the zones under each system - same as the
component tree under the HVAC tab.  Scan through those listings, and I
expect you'll see what triggered this comment from your reviewer, if it
isn't already apparent ;).  

 

~Nick

 

 

 

NICK CATON, E.I.T.

PROJECT ENGINEER

Smith & Boucher Engineers

25501 west valley parkway

olathe ks 66061

direct 913 344.0036

fax 913 345.0617

www.smithboucher.com 

 

From: equest-users-bounces at lists.onebuilding.org
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Jeff
Ross-Bain
Sent: Wednesday, May 04, 2011 11:00 AM
To: 'Bishop, Bill'; 'Paul Diglio'; 'equest-users'
Subject: Re: [Equest-users] Thermal Blocks

 

Here is the comment - it could be that I drew a blank - the comments so
far have helped to clear up the issue. I initially interpreted the
comment to imply a separate shell for each thermal block. 

 

According to the SV-A report, the Baseline Case was not modeled with a
separate PSZ-AC serving each thermal block as requested.

 

However, I do appreciate the comments regarding thermal blocks and they
have been very helpful.

 

Thanks for the response,

 

Jeffrey G Ross-Bain, PE, LEED AP, BEMP

404-228-2893 office 

404-408-2577 mobile
www.rbgb.com

________________________________

From: Bishop, Bill [mailto:wbishop at pathfinder-ea.com] 
Sent: Wednesday, May 04, 2011 11:18 AM
To: Paul Diglio; Jeff Ross-Bain; equest-users
Subject: RE: [Equest-users] Thermal Blocks

 

I'm also curious to hear Jeff's LEED reviewer interpretation of thermal
blocks. I'll add some general comments.

 

I believe it is incorrect use of terminology to talk about "multiple
zones per thermal block" in eQUEST.

 

The words space and zone both have specific meanings in eQUEST. For each
space, there is a single corresponding zone.

Multiple zones can be applied to a single system. (Unfortunately,
multiple systems cannot be applied to a single zone, but that is another
thread.)

The term thermal block does not have a precise meaning in eQUEST, but I
would not describe the group of zones assigned to a single system as a
thermal block.

 

If you wanted to try to model the exact intent of a proposed design, you
would model each thermally-unique area as its own space/zone. A
generalization is that a zone is an area served by a single thermostat.

To simplify a model, similar zones can be combined into thermal blocks
per the guidelines in ASHRAE Standard 90.1.

Modelers have to make judgments calls on if/how to combine zones into
thermal blocks.

 

In eQUEST, the decision to combine zones into thermal blocks really
should be done at the wizard input level, when the zones are defined.
You combine multiple zones per the design intent into a single zone
definition for simulation purposes.

You don't have multiple zones in a thermal block. Each thermal block is
defined/modeled as a single eQUEST zone.

You could still assign multiple thermal blocks/zones to a single system,
but I would be wary of over-simplifying a proposed design.

 

Regards,

Bill

 

 

 

From: equest-users-bounces at lists.onebuilding.org
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Paul
Diglio
Sent: Wednesday, May 04, 2011 9:21 AM
To: Jeff Ross-Bain; equest-users
Subject: Re: [Equest-users] Thermal Blocks

 

Jeff:

ASHRAE 90.1 allow spaces of similar thermal characteristics to be
combined in thermal blocks.  I do not include what you call support
spaces because the load and occupancy is much different than, say a
classroom.  I would define the corridor as a separate zone within the
thermal block but served by the same HVAC system.  This allows you to
have a different set-point, airflow, occupancy and schedules for the
corridor.

You do not have to define a separate shell for each block, you can
define the block by custom zones in the wizard.

I divide up a thermal block into as many reasonable zones as possible.
This allows me to find out which area of the thermal block is causing
any unmet heating or cooling hours.  It also allows me to change the
HVAC system control zone to that zone which is the hardest to satisfy in
the summer and winter.  These zones can be served by a single HVAC
system.

For a proposed model that needs to conform to an actual design, defining
multiple zones per thermal block allows you to balance the airflow to
zones that have unmet hours without increasing the overall airflow of
the HVAC system.  I define the zonal airflow in the Zone tab.  I reduce
the airflow to the zones without any unmet hours and increase the
airflow to those zones that have unmet hours.  I do not define the total
fan CFM in the Airside Systems tab.

What were the comments from the LEED reviewer?

Paul Diglio

 

 

________________________________

From: Jeff Ross-Bain <jeff at rbgb.com>
To: equest-users <equest-users at lists.onebuilding.org>
Sent: Wed, May 4, 2011 9:05:15 AM
Subject: [Equest-users] Thermal Blocks

Hi All,

 

Are there any additional discussions out there regarding thermal blocks
besides what is in ASHRAE Standard 90.1 and the User's Guide? I have
received comments back from a LEED reviewer that seems to reflect an
interpretation of that concept which I have not seen before.

 

In a nutshell, does each thermal block require a separate shell with
individual HVAC system? I understand the concept of having individual
thermal blocks or combining these if they are similar space use
categories. I am assuming then that the similar space use categories
(say a college classroom building) can also include support spaces such
as corridors, storage spaces, faculty offices, etc. 

 

So if several thermal blocks are combined into one, can they not be
served by a single, similar type of HVAC system?

 

I hope that I have made myself clear and many thanks for your thoughts
and comments.

 

Regards,

 

Jeffrey G Ross-Bain, PE, LEED AP, BEMP

404-228-2893 office 

404-408-2577 mobile
www.rbgb.com

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20110504/65857e1b/attachment-0002.htm>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: image/jpeg
Size: 1459 bytes
Desc: image002.jpg
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20110504/65857e1b/attachment-0004.jpeg>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: image/jpeg
Size: 20862 bytes
Desc: image003.jpg
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20110504/65857e1b/attachment-0005.jpeg>