[Bldg-sim] Unconditioned Zones

[Whately, Tyler]

Caroline,

I agree with Bill's remarks and you should first see if you can define
that space as "unconditioned" per ASHRAE's definition to get out of the
requirement all together. 

All,

I wanted to see what others peoples thoughts are when we have these
conditioned spaces and must provide heating or cooling even if we really
do not have them in proposed design per Table G3.1, 10. HVAC system. I
have used the method Caroline mentions of raising or lowering set points
in these "non-existing" systems to reduce or eliminate any effect on
simulation comparison.  This seems like a good approach, just wondering
if anyone else thinks this is a valid way to go about this?  A common
case for us would be a data room, where cooling is only provided or a
mechanical equipment room where heating is only provided and heating
output capacity is above the 3.4 Btu/h-sf.

Thanks,

Tyler Whately, E.I.T.
Mechanical Engineer
LEED Accredited Professional

MOSELEY ARCHITECTS
Architecture. Engineering. Interiors. Planning
3200 Norfolk Street
Richmond,  VA 23230
804.794.7555
FAX 804.355.5690
www.moseleyarchitects.com
www.moseleyprojects.com

Please consider the environment before printing this e-mail.


-----Original Message-----
From: Bishop, Bill [mailto:wbishop at pathfinder-ea.com] 
Sent: Thursday, March 04, 2010 2:00 PM
To: Caroline Fluhrer; bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] Unconditioned Zones

Caroline,

I'd argue that the space is unconditioned and requires no heating or
cooling, provided it really is "unconditioned" per the ASHRAE
definition. (See below.)

Per the ASHRAE 90.1 User's Manual (2004 & 2007), p. G-21, regarding
requirements for modeling both heating and cooling:

"This requirement only applies to conditioned space in the building.
Semiheated spaces would only have a heating system; unconditioned spaces
would have neither heating nor cooling systems."

Your "unconditioned zone" meets the ASHRAE definition (see p.13 in the
Standard) unless it is an "enclosed space...heated or cooled indirectly
by being connected to adjacent spaces" and receives 3 air changes per
hour of transfer air. 

Regards,
Bill

William Bishop, EIT, LEED(r) AP | Pathfinder Engineers & Architects LLP
Mechanical Engineer

134 South Fitzhugh Street
Rochester, NY 14608
T: (585) 325-6004 Ext. 114
F: (585) 325-6005

wbishop at pathfinder-ea.com
www.pathfinder-ea.com
P Please strive to live sustainably.

-----Original Message-----
From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Caroline
Fluhrer
Sent: Thursday, March 04, 2010 11:50 AM
To: bldg-sim at lists.onebuilding.org
Subject: [Bldg-sim] Unconditioned Zones

Hi there,

I am responding to some LEED review comments regarding a small
building in Hawaii that only has 2 thermal zones. In reality one of
these zones is conditioned (small split system cooling only) and one
zone is unconditioned (naturally ventilated, no heating or cooling).
The LEED reviewer writes:

"ASHRAE 90.1-2004 Table G3.1.1(b) in the proposed building column
requires that all spaces that are conditioned and occupied in the
proposed design should be simulated as being both heated and cooled
even if no cooling or heating systems are to be installed per Table
G3.1.1(b) in the proposed building column." - this comment makes sense
per G3.1.1b.

The comment continues "Based on the building area, number of floors,
and principal heating source, system type 4: packaged rooftop heat
pump should be modeled for the unconditioned spaces and heating
component of system type 4: packaged rooftop heat pump should be
modeled for the conditioned office spaces unit. Please revise the
proposed and baseline models by modeling the same system type in both
cases in the unconditioned spaces and include heating equipment for
the conditioned office spaces." This second comments seems to say that
I need to put System Type 4 in the unconditioned space in both the
baseline and the proposed model ... does this seem to correct to
others?

If so, it seems to imply that you can never truly have an
unconditioned space in a LEED model? As a workaround, I plan to then
put the setpoints for cooling and heating such that those installed
systems will never turn on (which makes me wonder why a system should
be installed). If I don't do wide setpoints, my proposed model will
not be representative of the actual energy use of the design building.

Any thoughts on this topic would be much appreciated.

Caroline



--
Caroline E. Fluhrer
Built Environment Team
Rocky Mountain Institute

1820 Folsom St.
Boulder, CO 80302 USA
Main: 303.449.5226
Direct: 303.567.8631
Fax: 303.567.8626
Email: cfluhrer at rmi.org
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