[Equest-users] HHW reset controls in eQuest

[Busman, Michael R]

Dominique,

Let me preface by saying that for years I've joked that the San Diego climate is so benign you could remove the walls and roof (or at least their insulating values) and it won't affect loads much.

I only had time to look at a few things quickly, which might explain some of your questions.  I've noticed in the past that using the EEM wizard inserts some default values that you might not be aware of.  For example, on air-cooled DX equipment if you specify an evaporative pre-cooler before the condenser, pumping power gets inserted.  If you have a pre-cooler with no pump that operates on building supply pressure, you have to go into detailed edit mode to zero out the pump power.  In the DD wizard you can also see some of the default values on the air-side or water side tabs and clicking on a component.

Anyway, your gas goes up a little in the economizer run.  The baseline for system #1 shows 0% outside air in the DD Wizard Project Navigator.  Without looking at hourly zone loads, it's possible the system is trying to satisfy the cooling of a zone with O.A. and causing some additional heating in other zones.

In the HHW variable flow run, electric only goes down 1% and gas goes up 5%.  If you click on the waterside tab of the DD Wizard screen, you'll see you have an atmospheric boiler located outdoors.  In this instance, this might not make much difference, but this boiler type and location could have higher standby losses.  If you click the airside tab, you'll see that you have 3-way hot water valves.  A 3-way valve system design is going to be virtually constant volume all the time.  Looking at the PS-E end use energy report shows that the reduction in electric is from pumping.  Not a lot of kWh, but this will result in less pump heat added to the HHW and the amount of increased gas is within reason if you convert the kWh to therms (about 127 therms of heat, not gas). Not all of the electric is going to end up as pump heat gain. If the motor is air-cooled, that drops the difference between the 127 therms of heat and 72 therms of increased gas, so the increase is within reason.

The 5 kWh in electric for the HHW supply temp reset run may be the result of a few hours that the VFDs have to speed up to satisfy zone temps.  It's so small to be insignificant.  No difference in gas consumption is hard to comment on without studying the input file or consulting the DOE-2 manuals.  You might want to do this to see what calculation algorithms are used, how much piping is assigned and how it is assigned, what pipe insulating values, or if the program defaults to the piping being located in conditioned or unconditioned space.

Sorry I couldn't be more helpful but I don't have the time today to explore this deeper.  For shakes and giggles, you might try changing the weather file to someplace like Chicago and see what kind of results you get.

My best,

Mike Busman


Michael R. Busman, CEM
Lead Project Engineer II

Chevron Energy Solutions
A Division of Chevron U.S.A., Inc.
145 S. State College Blvd.
Brea, CA  92821
Direct  714-671-3561
Fax     714-671-3438
eFax   866-420-0335 (Include my Full Name followed by "CAI:MHTZ" on Cover Sheet)
Mobile 310-387-2083
mbusman at chevron.com<mailto:mbusman at chevron.com>



From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Dominique Michaud
Sent: Tuesday, September 17, 2013 9:51 AM
To: equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] HHW reset controls in eQuest

Fellow eQuest modelers,

I'm reposting my last query (see below) with an example of one of the eQuest models that I have been having trouble with. Again, I'm having trouble modeling some very simple (IMO) heating hot water/boiler energy efficiency measures. I'm just not seeing the amount of savings I'm expecting. I'm even seeing negative savings for some measures (this is especially frustrating).

My offer of a beer to anyone who helps me solve my problem still stands, though I'll have to restrict my offer to US/Canada destinations. Did I mention I'm in San Diego<http://travel.nytimes.com/2012/05/27/travel/san-diegos-thriving-craft-beer-scene.html?pagewanted=all&_r=0>?

Thanks in advance for your help.

Dominique Michaud | Project Engineer
SC Engineers, Inc. <http://www.scengineers.net/>
17075 Via Del Campo, San Diego, CA 92127<http://maps.google.com/maps?hl=en&cp=40&gs_id=2&xhr=t&q=17075+Via+Del+Campo,+San+Diego,+CA+92127&gs_upl=&bav=on.2,or.r_gc.r_pw.,cf.osb&biw=1280&bih=583&wrapid=tljp132371020953200&um=1&ie=UTF-8&hq=&hnear=0x80dbf72707811bcf:0xafda74b7e473e651,17075+Via+Del+C>
P: 858.946.0333 | C: 858.436.4213 |F: 858.946.0334
dominique at scengineers.net<mailto:dominique at scengineers.net> | www.scengineers.net<http://www.scengineers.net/>



From: Dominique Michaud [mailto:dominique at scengineers.net]
Sent: Friday, September 13, 2013 5:35 PM
To: 'equest-users at lists.onebuilding.org'
Subject: HHW reset controls in eQuest

Fellow eQuest modelers,

I am experiencing a great deal of grief trying to model HHW/boiler energy efficiency measures using eQuest. I am trying to model HHW temperature resets based on outside air temperature and boiler lockout strategies.

Under the DD Wizard, "Hot Water System Control and Schedule > Setpoint is:"  drop-down list I've selected "OA Reset" and allowed the resulting hi/low temperature values to default, namely HW Max Temp: 180.0F and HW Min Temp: 140.0F (see attached screenshot).

Digging into the BDL, I noticed this issue:

     *5356 * "B5HW Lp Heat Reset Sch-D" = DAY-SCHEDULE-PD
     *5357 *    TYPE             = RESET-TEMP
     *5358 *    SUPPLY-LO        = 140
-CAUTION-------------------------- === -------------------------------------------------------
-CAUTION--- VALUE GREATER THAN MAXIMUM OF 0.1200E+03
     *5359 *    SUPPLY-HI        = 180
-CAUTION-------------------------- === -------------------------------------------------------
-CAUTION--- VALUE GREATER THAN MAXIMUM OF 0.1200E+03
     *5360 *    OUTSIDE-LO       = 30
     *5361 *    OUTSIDE-HI       = 65
     *5362 *    ..

However, it looks as though the values are accepted for the reset schedule:

-NOTE- - -         DATA FOR     B5HW Lp Heat Reset Sch-D
-INPUT - - - - - - - - - - - - - - - - - - - - - - - -  TYPE             = RESET-TEMP
-INPUT - -                                              OUTSIDE-HI       =                      65.0000 F
-INPUT - -                                              OUTSIDE-LO       =                      30.0000 F
-INPUT - -                                              SUPPLY-HI        =                     180.0000 F
-INPUT - -                                              SUPPLY-LO        =                     140.0000 F
-DEFAULT - - - - - - - - - - - - - - - - - - - - - - -  DAY-HOURS        =                       1.0000
-DEFAULT -                                              DAY-HOURS        =                      24.0000


When I run the model I end up negative natural gas savings (i.e. more gas usage than in my baseline case). No matter what dials I try to turn with this EE measure, I consistently end up with negative savings. Even more frustrating, when I try to run a OA temperature lockout for the boiler, I get even more energy use than my baseline model!

Can anyone provide me with some guidance on what I need to do to get my model to run these EEMs correctly? Help put me on the path to solving these problems and I will buy you a beer...

(Note: I am using eQuest 3.64 Build 7130 - the latest release)

Thank you for any assistance you can provide.

Yours,

Dominique Michaud | Project Engineer
SC Engineers, Inc. <http://www.scengineers.net/>
17075 Via Del Campo, San Diego, CA 92127<http://maps.google.com/maps?hl=en&cp=40&gs_id=2&xhr=t&q=17075+Via+Del+Campo,+San+Diego,+CA+92127&gs_upl=&bav=on.2,or.r_gc.r_pw.,cf.osb&biw=1280&bih=583&wrapid=tljp132371020953200&um=1&ie=UTF-8&hq=&hnear=0x80dbf72707811bcf:0xafda74b7e473e651,17075+Via+Del+C>
P: 858.946.0333 | C: 858.436.4213 |F: 858.946.0334
dominique at scengineers.net<mailto:dominique at scengineers.net> | www.scengineers.net<http://www.scengineers.net/>

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