[Equest-users] Design day for Appendix G Baseline sizing runs

[Paul Diglio]

John:

In reference to the ASHRAE 90.1-2007 HVAC form that needs to be uploaded to 
LEED, I interpret  the Mandatory Provisions, page 2 entries for 1% Summer DB, 1% 
Summer WB and 99.6% Winter Temp to mean that the model must use these design 
temperatures.

Do you agree?

Paul Diglio




________________________________
From: John T. Forester <JohnTF at BVHis.com>
To: "Bishop, Bill" <wbishop at pathfinder-ea.com>
Cc: "equest-users at lists.onebuilding.org" <equest-users at lists.onebuilding.org>
Sent: Wed, January 12, 2011 1:25:59 PM
Subject: Re: [Equest-users] Design day for Appendix G Baseline sizing runs

Hi Bill,

I've created custom design days in past projects based on the 1% CDD and 99.6% 
HDD and it has actually helped reduce unmet load hours by increasing coil sizes, 
especially in DOA systems.  Chapter 14 of the ASHRAE Fundamentals book will give 
you the climatic data for your location.  You might need the electronic version 
as I don't believe every location is printed in the hard text these days.  The 
data also shows which month is the hottest and coldest.  The data the bottom 
half of the page gives temperature ranges for drybulb and coincident DB/WB for 
each month.  The difference in ranges each month will depend on your location.  
Here in Boston, the hottest month (July) has a DB range of 15.2°F and the 
coldest month (January) has a range of 13.1°F

I've also come across instances where the wizard somehow hard-codes erroneous 
temperatures causing many unmet load hours and troubleshooting will not get you 
anywhere if eQuest is using the wrong design temperatures.  Now, I make a point 
to check the CDD and HDD of all of my models.

John

John T. Forester, P.E., LEED AP, Mechanical Design Engineer I BVH Integrated 
Services I 617.658.9008 tel I 617.244.3753 fax I One Gateway Center Suite 506, 
Newton MA 02458 I www.bvhis.com I Hartford ● New Haven ● Boston
________________________________________
From: equest-users-bounces at lists.onebuilding.org 
[equest-users-bounces at lists.onebuilding.org] On Behalf Of Carol Gardner 
[cmg750 at gmail.com]
Sent: Wednesday, January 12, 2011 12:32 PM
To: Bishop, Bill
Cc: equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] Design day for Appendix G Baseline sizing runs

Hi Bill,

I don't recommend using design days instead of the weather file at this time. I 
have heard in the past that the HDD and CDD schedules that are automatically 
generated don't actually work for sizing if you don't live in California. I 
can't remember the exact details of that rumor but perhaps someone else will. I 
also have heard in the past that it is better to use the weather files as using 
the design day method tends to underpredict the size of the systems. That's all 
we need!  More hours loads not met, yikes!!

So it would be a significant amount of extra work for no real gain.

Cheers,

Carol

On Wed, Jan 12, 2011 at 9:16 AM, Bishop, Bill 
<wbishop at pathfinder-ea.com<mailto:wbishop at pathfinder-ea.com>> wrote:
I have been letting eQUEST determine baseline equipment capacities using the 
weather files selected by the wizard, rather than creating 99.6%/1% design days 
as allowed by G3.1.2.2.1. Does anyone recommend using design days for 
LEED/Appendix G baselines? If so, how do you determine DRYBULB-RANGE, or do you 
set it to zero to run the same DRYBULB-HIGH temperature 24/7/365? Does the 
design day method typically maximize baseline energy consumption compared to 
TMY/TMY2 weather files?

Thanks,
Bill

William Bishop, PE, BEMP, LEED® AP | Pathfinder Engineers & Architects LLP
Mechanical Engineer

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--
Carol Gardner PE
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