[bldg-sim] Modeling buildings with natural ventilation forAppendix G

Michael,

I cannot find Addendum AG - it is not on the list of approved addenda and I
cannot find it under the public review drafts. Can you point me to where I
might find it?

Marcus Sheffer
Energy Opportunities, Inc/a 7group Company
1200 E Camping Area Road, Wellsville, PA 17365
717-292-2636, sheffer@xxxxxxxxxxxxxx
www.sevengroup.com

-----Original Message-----
From: Michael Rosenberg [mailto:Michael.Rosenberg@xxxxxxxxxxx]
Sent: Thursday, December 21, 2006 4:03 PM
To: bldg-sim@xxxxxxxx; sheffer@xxxxxxxxxxxxxx
Subject: Re: [bldg-sim] Modeling buildings with natural ventilation
forAppendix G

Marcus,

I am on the ASHRAE 90.1 ECB subcommittee. I do not think at this point
that we are working on any additional methodology to credit natural
ventilation. Addendum AG already changed the following:

In the proposed building.
HVAC Fan Schedules. Schedules for HVAC fans that provide outdoor air
for ventilation shall run continuously whenever spaces are occupied and
shall be cycled on and off to meet heating and cooling loads during
unoccupied hours.

This implies that HVAC fans that are only meeting thermal load may
cycle on and off, and was meant to allow fan credit for natural
ventilation system (as simple as operable windows). The proposed
building still calls for cooling as a requirement, but the thought is,
that if model simulates natural ventilation and the cooling load is met
that way, the fan and cooling coil will not operate to meet load and the
design will be credited. The problem is that most LEED models are done
using DOE2, which has severe limitations when it comes to modeling
natural ventilation. It is my understanding that other programs do a
better job of this.

The subcommittee also thought that an exceptional calculation method
might be used if the natural ventilation simulation was be done in a
stand alone program and then an appropriate infiltration schedule was
input into a program like DOE2, reducing the use of mechanical cooling.

Mike

Michael Rosenberg
Oregon Department of Energy
625 Marion St. N.E.
Salem, OR 97301-3742
Phone : (503) 373-7809
Fax: (503) 373-7806

>>> "Marcus Sheffer" <sheffer@xxxxxxxxxxxxxx> 12/21/06 11:58AM >>>
Mike,

The exception calculation method you describe is absolutely correct.

Obtaining savings for natural ventilation within LEED however is
another
story. I am one of the certification reviewers and also vice-chair of
the
EA TAG. My understanding is that to date the USGBC has not allowed
natural
ventilation to fully count under EAc1 even if submitted as an
exceptional
calculation method. The TAG is awaiting the work of the 90.1
subcommittee
you mention to develop a uniform methodology.

Perhaps your submission will be the one to set the precedent. Thanks
to all
for helping to blaze the trail.

Marcus Sheffer

Energy Opportunities, Inc/a 7group Company

1200 E Camping Area Road, Wellsville, PA 17365

717-292-2636, <mailto:sheffer@xxxxxxxxxxxxxx> sheffer@xxxxxxxxxxxxxx

www.sevengroup.com

_____

From: bldg-sim@xxxxxxxx [mailto:bldg-sim@xxxxxxxx] On Behalf Of Mike
Tillou
Sent: Thursday, December 21, 2006 2:03 PM
To: bldg-sim@xxxxxxxx
Subject: [bldg-sim] Modeling buildings with natural ventilation for
Appendix
G

Not yet...I have a project with natural ventilation using this method
that
will be submitted for final review in Feb-Mar 2007.

MMT

Michael Tillou, PE
ETC Group, Inc - Energy Engineering for a Sustainable Future
Ph:413-458-9870

-----Original Message-----
From: bldg-sim@xxxxxxxx [mailto:bldg-sim@xxxxxxxx] On Behalf Of Peter
Alspach
Sent: Tuesday, December 19, 2006 1:34 PM
To: bldg-sim@xxxxxxxx
Subject: [bldg-sim] Modeling buildings with natural ventilation for
Appendix
G

Mike,

Have you succeeded in getting a naturally ventilated building through
the
USGBC with this method?

If so, I am sure all would be glad to hear it.

Peter

_____

From: bldg-sim@xxxxxxxx [mailto:bldg-sim@xxxxxxxx] On Behalf Of Mike
Tillou
Sent: Tuesday, December 19, 2006 7:18 AM
To: bldg-sim@xxxxxxxx
Subject: [bldg-sim] Modeling buildings with natural ventilation for
Appendix
G

Ramana,

The ASHRAE 90.1 ECB sub-committee is working on a methodology for
simulating
natural ventilation within the framework of Appendix G but I don't
think its
finished yet. In the meantime here is what I would recommend.

Appendix G / 90.1 ECB allows you to use an exception calculation method
to
simulate hybrid systems or unique efficiency measures to demonstrate
above-standard performance. I think this would certainly apply in
your
case.

Here's what I have done on projects requiring an exception calculation
method.

1. Establish your energy cost budget and your design energy case
following
the Appendix G guidelines.

2. Create a second model using the Design Energy Case as the baseline
and
make the necessary modifications to simulate radiant heating / no
cooling
via natural ventilation.

3. Report the energy savings from your exception calculation as a line
item
at the end of your LEED EA-1 summary table (similar to how renewable
energy
is reported).

4. Include a seperate summary table for the exception calculation
showing
the energy end-use breakdown and how you arrived at the cost savings.
Show
both the baseline and proposed energy use.

5. Make sure the savings are reasonable and prudent for the system you
are
proposing.

6. Document any changes to the model especially changes to schedules
that
were necessary to properly simulate your system.

7. Make it easy for someone to review your assumptions and the
methodology
you used to estimate the savings

I hope this helps. Good luck.

Mike

Michael Tillou, PE
ETC Group, Inc - Energy Engineering for a Sustainable Future
Ph:413-458-9870

-----Original Message-----
From: bldg-sim@xxxxxxxx [mailto:bldg-sim@xxxxxxxx] On Behalf Of Ramana
Koti
Sent: Monday, December 18, 2006 4:53 PM
To: bldg-sim@xxxxxxxx
Subject: [bldg-sim] Modeling buildings with natural ventilation for
Appendix
G

Dear all,

Is ignoring natural ventilation in both proposed and baseline designs
an
accepted/fair way of modeling based on Appendix G (ASHRAE 90.1-2004)?

Part of the proposed design has (radiant heating + natural ventilation)
with
no cooling which was modeled as a radiant slab, no cooling, natural
ventilation ignored.

But the Baseline HVAC system based on Appendix G is System 5: Packaged
VAV
w/Reheat. (Natural ventilation can be modeled based on Air Change
method or
Sherman Grimsrud method though I do not know how to do it).

I cannot decide how to make the baseline and proposed comparable with
respect to Natural Ventilation (in a manner acceptable to LEED
review),
suggestions will be appreciated.

Thanks,

Ramana Koti, Sustainable Building Analyst
LEED AP

ELEMENTS | a division of berkebile nelson immenschuh mcdowell
architects
106 W. 14th Street Suite 200
Kansas City, Missouri 64105

p 816.783.1635 f 816.783.1501
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