[Equest-users] equest results for system sizing

Mon Sep 19 14:23:52 PDT 2011

Just to throw it into the discussion...eQuest does accept design day inputs.  In Detailed mode, they can be input under the "Project & Site" tab (one each, heating and cooling).  The keywords are covered under "Envelope Components" in the DOE2.2 Volume 3: Topics manual in the help files.  For each design day, the schedules are allowed to be different from the schedules used in the annual simulation so there are keywords for that also.

Is there some reason this wouldn't be used for load calculations?

Jeremy R. Poling, PE, LEED AP+BDC

________________________________

From: equest-users-bounces at lists.onebuilding.org on behalf of Pasha Korber-Gonzalez
Sent: Mon 9/19/2011 10:01 AM
To: Deepika
Cc: equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] equest results for system sizing

Hi Deepika,

The answers you are looking for are dependent on what you are trying to achieve.   As Will had stated that it is not a great idea to use building energy simulation programs as load calculation programs.  The reason for this is two fold:
1)  Only use your tools for what they were designed for---you wouldn't cut an apple with a chain saw, when a simple paring knife will do a much more accurate and efficient job at slicing the apple.   With that example, eQuest/DOE-2 are designed to estimate whole building energy consumption.   It can perform load calculations and analysis, however the energy models are typically an "average" profile of energy use throughout a one year period.   The program doesn't properly size HVAC equipment for the peak heating or cooling days, as it is not always likely that the weatehr file you are using will represent these peak design days that HVAC designers are held too for life-safety purposes.

2)  With so many potential variable unknowns if you are not an experience eQuest/DOE2.2 user there is much opportunity for risk in your design calculations.  As Will pointed out, it is stated very clearly on the building loads reports that these "design load" calcs do not include the impact of ventilation air requirements.  The closest place you can extract this number is from the SV-A reports for each of the HVAC systems you have in your model.  

Are you in the process of designing your building using eQuest, or are you using eQuest to evaluate your HVAC design?  Dependent on your answer will guide how you use eQuest/DOE2.2 to accomplish your task at hand.    

If you are performing your building design load calculations, I also highly recommend that you do not use any whole building energy sim program for that purpose.  Choose another load program (i.e Trace or HAP) and then once you have a completed set of design load calcs then it would be good practice to building your whole building energy model and compare the calculated simulation results with your official design load calcs to find where some of the detail might have been lost.

I've attached a DOE-2.2 document from the eQuest developers that can be used as a navigational reference for the DOE-2 output reports and what types of information and variables can be referenced in each report.  The SV-A report is an output for each AHU (HVAC air system) that you have in your model.  From this report you can find the overall Supply air flow (CFM), and htg & clg capacities.   To find the equipment capacities for your plant equipment you will need to reference the "P" reports in your sim file.

Cheers,
Pasha

On Mon, Sep 19, 2011 at 8:31 AM, Deepika <deepika.khowal at gmail.com> wrote:

	Thanks for the inputs. . 
	So typically use the kw numbers from Equest and use it in trace ? 
	Do you also add a sizing factor ? 

	On Sep 19, 2011, at 6:49 AM, PKConsulting <pasha.pkconsulting at gmail.com> wrote:

		Deepika
		Use the sv-a reports for ahu sizing.

		Pashalu

		On Sep 19, 2011, at 6:33 AM, "Will Mak" < <mailto:wmak at epsteinglobal.com> wmak at epsteinglobal.com> wrote:

			Honestly, I don't like using eQuest for load calcs. I typically use Trane Trace or HAP...

			Especially since the load summary states in big letters that ventilation is not accounted for in the calcs. You could do them separately but still...

			Just my 2 cents.

			William Mak, LEED AP BD+C
			Mechanical Design Engineer

			EPSTEIN
			600 West Fulton Street
			Chicago, Illinois 60661-1259
			D: (312) 429-8116

			From: <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 deepika khowal
			Sent: Sunday, September 18, 2011 5:33 PM
			To: <mailto:equest-users at lists.onebuilding.org> <mailto:equest-users at lists.onebuilding.org> equest-users at lists.onebuilding.org
			Subject: [Equest-users] equest results for system sizing

			Hi all

			I would like to know to get an idea for system sizing based on modeling in equest.

			where in equest do everyone look for sizing Numbers?

			I have always been looking at design sizing tons from air side HVAC tab. But I realized they are very different from detailed report sizing.

			If anyone can direct me through this, it will be helpful.

			1.       Using air-side HVAC summary : design sizing tons

			<image001.jpg>

			2.       Using building peak components, taking the kbtu/hsf number and diving by 12000 to get cooling tons. This number is very low compared to design capacity.

			<image002.jpg>

			3.       Using PS-C report

			<image003.jpg>

			Is there any other report which mechanical designers use to size system?

			Thanks

			 Deepika

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