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

[John T. Forester]

Hi Bill,

The simplified compliance path (document referenced below) only becomes an option for projects where the building is two stories or fewer with a gross floor area less than 25,000 sft.

That said, Section G3.1.2.2.1 (page 180 of 90.1-2007) states the following:

Sizing Runs.  Weather conditions used in sizing runs to determine baseline equipment capacities may be based either on hourly historical weather files containing typical peak conditions or on design days developed using 99.6% heating design temperatures and 1% dry-bulb and 1% wet-bulb cooling design temperatures.

It seams clear now that either method is acceptable for App. G compliance.

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<http://www.bvhis.com> I Hartford ● New Haven ● Boston

-----Original Message-----
From: Bishop, Bill [mailto:wbishop at pathfinder-ea.com]
Sent: Thursday, January 13, 2011 9:48 AM
To: John T. Forester; Paul Diglio; Carol Gardner; Howe, Timothy
Cc: equest-users at lists.onebuilding.org
Subject: RE: [Equest-users] Design day for Appendix G Baseline sizing runs

Thanks everybody for your replies!

John, Paul,
Are you referring to this document?:
http://www.ashrae.org/docLib/20080827_9012007_6HVACForms.pdf
While I don't think it's a big deal, I disagree that the use of this document requires the baseline model to be sized using the design day information provided on this form, for three reasons. One, this document is optional for LEED, not required, according to the Beta version of the EAp2 online template that I last used. Two, while I can only guess the intent of the form, the design day section of the form appears to be for reference only (containing other general information such as name, address). I do not see any wording in ASHRAE Standard 90.1-2007 that requires 1%/1%/99.6% temps to be used for mechanical design. Three, this document is for the proposed design. Appendix G specifically says a weather file can be used to size the baseline equipment.

Regards,
Bill Bishop

-----Original Message-----
From: John T. Forester [mailto:JohnTF at BVHis.com]
Sent: Wednesday, January 12, 2011 2:08 PM
To: Paul Diglio; Bishop, Bill
Cc: equest-users at lists.onebuilding.org
Subject: RE: [Equest-users] Design day for Appendix G Baseline sizing runs

Hi Paul,

Yes, I agree.  I'm just not sure how often the HDD and CDD inputs get reviewed/commented on by the USGBC review teams.  Overall for most locations, the default weather file method in eQuest will get you very close to the correct values.

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<http://www.bvhis.com> I Hartford ● New Haven ● Boston
________________________________________
From: Paul Diglio [paul.diglio at sbcglobal.net]
Sent: Wednesday, January 12, 2011 1:58 PM
To: John T. Forester; Bishop, Bill
Cc: equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] Design day for Appendix G Baseline sizing runs

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<http://www.bvhis.com> I Hartford ● New Haven ● Boston
________________________________________
From: equest-users-bounces at lists.onebuilding.org<mailto:equest-users-bounces at lists.onebuilding.org> [equest-users-bounces at lists.onebuilding.org<mailto:equest-users-bounces at lists.onebuilding.org>] On Behalf Of Carol Gardner [cmg750 at gmail.com<mailto:cmg750 at gmail.com>]
Sent: Wednesday, January 12, 2011 12:32 PM
To: Bishop, Bill
Cc: equest-users at lists.onebuilding.org<mailto: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><mailto: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(r) AP | Pathfinder Engineers & Architects LLP
Mechanical Engineer

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Carol Gardner PE
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