[Equest-users] Fixing unmet hours / outside of throttling range warnings
Mark Darrall
MDarrall at a2so4.com
Mon May 16 08:59:23 PDT 2011
Ah, the difference a setting can make! After playing with throttling ranges and sizing factors and getting only tiny improvements, looking at the zone temperature reports got me thinking to what was happening overnight. I then realized the AHU fans were set to never come on on night cycle, so the building was overheating at night!
Setting night cycle control to "Cycle on First" took care of it all! I now have unmet hours under 150 hours for both models and the design case unmet hours are fewer than baseline. I think I got it!
Thanks for all the help!
MARK DARRALL, AIA, LEED AP BD+C, NCARB
Senior Project Manager
[cid:image001.jpg at 01CC13C0.AF288A60]
DESIGN ENRICHING LIFE // LIFE ENRICHING DESIGN
A2SO4 Architecture, LLC
Union Station
300 South Meridian Street / 250
Indianapolis, Indiana 46225
TEL 317 388 8850
FAX 317 280 0692
MOB 765 749 0841
www.a2so4.com
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From: Mark Darrall [mailto:MDarrall at a2so4.com<mailto:MDarrall at a2so4.com>]
Sent: Tuesday, May 03, 2011 7:19 PM
To: David Eldridge
Subject: RE: [Equest-users] Fixing unmet hours / outside of throttling range warnings
I thought the hood would be one explanation for that. Yes; there is no latent load, either.
I knew I couldn't keep the refrigeration load out, but it was a good way to test my guess.
The system is only 4T, so the refrigeration alone ate up half of it. I found some information from the design engineer among the papers we were given, so I might be able to get into his head a little more on this.
It's nice to know I'm on the right track, though.
I have another problem, too. I don't have enough information on the windows to give certified window properties. The reviewers either want certified values, Window files, or they want us to use the Appendix A Table 8.2 values, which would also put a hurt on the energy use. Thankfully my two worst zones only have a small window each in them.
Do you know any successful workarounds for this problem? I downloaded Window and Thermal, but I really don't have time to learn more software right now. Will fabricators do these evaluations if I give them glass and frames (I might have enough info on hand to put together frame and glass systems).
Dave, thanks so much again.
MARK DARRALL, AIA, LEED AP BD+C, NCARB
Senior Project Manager
[cid:image001.jpg at 01CC13C0.AF288A60]
DESIGN ENRICHING LIFE // LIFE ENRICHING DESIGN
A2SO4 Architecture, LLC
Union Station
300 South Meridian Street / 250
Indianapolis, Indiana 46225
TEL 317 388 8850
FAX 317 280 0692
MOB 765 749 0841
www.a2so4.com
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From: David Eldridge [mailto:dse at grummanbutkus.com<mailto:dse at grummanbutkus.com>]
Sent: Tuesday, May 03, 2011 7:56 PM
To: Mark Darrall
Cc: Paul Diglio
Subject: Re: [Equest-users] Fixing unmet hours / outside of throttling range warnings
The cooking as a zero sensible factor reflects the range hoods drawing that load out before it "hits" the HVAC system. Latent is also zero, correct?
However the refrigeration equipment will actually be putting load onto the HVAC.
How does the 5 W/ft2 compare to the system capacity, as you mention 24,000 BTU/hr, plus lights, people, etc.
So if the HVAC System isn't sized similarly there should be unmet hours.
You need to consider the multiplier schedule for the refrigeration though, as the HVAC was designed for a certain load, which may not be the load all of the time. Or perhaps any of the time.
Changing it to a 0 sensible won't be the appropriate solution if the heat really is rejected to the space.
-DSE
Sent from my iPhone
On May 3, 2011, at 5:55 PM, Mark Darrall <MDarrall at a2so4.com<mailto:MDarrall at a2so4.com>> wrote:
Hi, David and Paul,
My worst zone is 1400 s.f. and includes a kitchen. There is a 30W/s.f. cooking load as well as 5W/s.f. refrigeration load. However, I see that EQUIP-SENSIBLE is 0 for the first, and 1 for the second. But even that is 24000BTUH. Hang on...I'm going to set that 0 and see what happens...YUP! That made the unmet cooling hours go away for that zone. I need to try to dig into what the designer had in mind for this. I think I'm on to something there. Because the other bad zone has a lot of office gear in it...
In the Air-side summary, I've got 1.86 cfm SA/s.f. and 361s.f/T of cooling. Those seem reasonable, at least to me.
Thanks - more later!
MARK DARRALL, AIA, LEED AP BD+C, NCARB
Senior Project Manager
<image001.jpg>
DESIGN ENRICHING LIFE // LIFE ENRICHING DESIGN
A2SO4 Architecture, LLC
Union Station
300 South Meridian Street / 250
Indianapolis, Indiana 46225
TEL 317 388 8850
FAX 317 280 0692
MOB 765 749 0841
www.a2so4.com<http://www.a2so4.com>
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From: David Eldridge [mailto:dse at grummanbutkus.com<mailto:dse at grummanbutkus.com>]
Sent: Monday, May 02, 2011 6:39 PM
To: Mark Darrall; Paul Diglio
Subject: RE: [Equest-users] Fixing unmet hours / outside of throttling range warnings
Is there enough diversity on the internal gains inside the spaces? It is possible that the results are accurately reflecting the input and the gains are too high from the equipment compared to the designer's capacity calculation? Also make sure you don't have any "stealth" gains listed out to the right in the scroll bar in spreadsheet view where you might be double-counting some gains. (lights or equipment)
Another consideration might be that the occupancy schedule and temperature schedules change together at the appropriate times.
Dead-band is the space between the two setpoints - i.e. 6F occupied between heat/cool and 12F unoccupied difference between heat/cool. This should be consistent with the terminology in design circles (and 90.1) as well.
Throttling range is how far off the temperature will get before the device is fully actuated, and goes in both directions of the setpoint, so for the 2F throttling range, the control will be fully activated for cooling at 77F, or 69F for heating...and I see Paul just attached a great description of it.
Anyway, there is likely something else keeping your zones from being controlled properly besides the throttling range. Do the CFM/SF and Ton/SF figures in the air-side summary tab make sense, total capacity for the building reasonable?
David
David S. Eldridge, Jr., P.E., LEED AP BD+C, BEMP, BEAP, HBDP
Grumman/Butkus Associates
From: Mark Darrall [mailto:MDarrall at a2so4.com<mailto:MDarrall at a2so4.com>]
Sent: Monday, May 02, 2011 2:47 PM
To: David Eldridge; Paul Diglio
Subject: RE: [Equest-users] Fixing unmet hours / outside of throttling range warnings
Hi, David and Paul,
Many thanks to you both. Design temps are 75 cooling, 72 heating. Looking at the cooling schedule, it's set for 76 degrees occupied, 82 unoccupied. Heat schedule is 64 unoccupied, 70 occupied. Each system handles one zone. I did not revise the airflow from the design unit sizes.
Cooling unmet hours are real bad for a couple of the zones. Heating unmet hours are minor.
SS-O for the first system (the worst one) shows almost 1700 hours between 75-80 degrees, and 1000 hours over 80 - all during occupied hours.
SO...
I revised the cooling and heating schedules to match the design temps; it only helped a little - moved more hours into the 70-80 deg range, but still had almost 1500 hours outside of range.
I then increased the throttling range from the default 2 degrees to 5 degrees and got the unmet hours down to 11% - almost 970 hours. Appendix G only limits us to 300 hours and within 50 of the baseline building.
How much can the throttling range increase? Is this the same as the 5 degree dead-band 90.1 references?
MARK DARRALL, AIA, LEED AP BD+C, NCARB
Senior Project Manager
<image001.jpg>
DESIGN ENRICHING LIFE // LIFE ENRICHING DESIGN
A2SO4 Architecture, LLC
Union Station
300 South Meridian Street / 250
Indianapolis, Indiana 46225
TEL 317 388 8850
FAX 317 280 0692
MOB 765 749 0841
www.a2so4.com<http://www.a2so4.com>
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From: David Eldridge [mailto:dse at grummanbutkus.com<mailto:dse at grummanbutkus.com>]
Sent: Monday, May 02, 2011 10:49 AM
To: Mark Darrall
Subject: RE: [Equest-users] Fixing unmet hours / outside of throttling range warnings
If you go to the Summary tab of the air-side systems, how do the unmet hours on the right hand side compare for these systems?
Check the SS-O reports for these systems also. Sometimes if the zone sizing temperatures and throttling range aren't consistent with the desired system temperatures there can be a "false unmet hour" reported even though SS-O is fine.
First look at the temperature setpoint for the zones in the zone definition and make sure it is consistent with the temperature schedules used by the AHUs.
David
David S. Eldridge, Jr., P.E., LEED AP BD+C, BEMP, BEAP, HBDP
Grumman/Butkus Associates
From: equest-users-bounces at lists.onebuilding.org<mailto:equest-users-bounces at lists.onebuilding.org> [mailto:equest-users-bounces at lists.onebuilding.org<mailto:equest-users-bounces at lists.onebuilding.org>] On Behalf Of Mark Darrall
Sent: Monday, May 02, 2011 8:21 AM
To: equest-users
Subject: [Equest-users] Fixing unmet hours / outside of throttling range warnings
Good Morning, eQUESTers,
I'm working on my design case model. Here's my ATTN report:
**WARNING**********************************************************************
SYSTEM EL1 Sys1 (PSZ) (G.NNW1) may have inadequate cooling capability
Check COOLING-CAPACITY and MIN-SUPPLY-T for consistency
**WARNING**********************************************************************
SYSTEM EL1 Sys2 (PSZ) (G.WSW2) may have inadequate cooling capability
Check COOLING-CAPACITY and MIN-SUPPLY-T for consistency
**WARNING**********************************************************************
SYSTEM EL1 Sys3 (PSZ) (G.N3) may have inadequate cooling capability
Check COOLING-CAPACITY and MIN-SUPPLY-T for consistency
**WARNING**********************************************************************
SYSTEM EL1 Sys4 (PSZ) (G.S4) may have inadequate cooling capability
Check COOLING-CAPACITY and MIN-SUPPLY-T for consistency
**WARNING**********************************************************************
SYSTEM EL1 Sys5 (PSZ) (G.N5) may have inadequate cooling capability
Check COOLING-CAPACITY and MIN-SUPPLY-T for consistency
**WARNING**********************************************************************
SYSTEM EL1 Sys6 (PSZ) (G.E6) may have inadequate cooling capability
Check COOLING-CAPACITY and MIN-SUPPLY-T for consistency
**WARNING**********************************************************************
SYSTEM EL1 Sys7 (PSZ) (G.C7) has zero outside air for design calculations
This last one I can answer as this system is a R/A only computer room cooler. For the others:
COOLING-CAPACITY comes directly from the HVAC designer and is the capacity of the installed units. I've tried adjusting MIN-SUPPLY-T from 55 to 50 (and this seems to jive with information the coil manufacturer provides) to get a larger delta-T and it only seemed to make things worse somehow. Minimum OSA is 20%, but again, this is a design condition. These units do have enthalpy-controlled economizers.
I'm also getting WAY too many hours outside of throttling range - 15%. My baseline model only has a 3%. I'm way out of whack with Appendix G requirements.
Any suggestions as to settings to modify to clear these? Thank you!
MARK DARRALL, AIA, LEED AP BD+C, NCARB
Senior Project Manager
<image001.jpg>
DESIGN ENRICHING LIFE // LIFE ENRICHING DESIGN
A2SO4 Architecture, LLC
Union Station
300 South Meridian Street / 250
Indianapolis, Indiana 46225
TEL 317 388 8850
FAX 317 280 0692
MOB 765 749 0841
www.a2so4.com<http://www.a2so4.com>
Please consider the environment before printing this e-mail.
CONFIDENTIALITY NOTICE: This email and any files transmitted with it are confidential and intended solely for the use of the individual or entity to which they are addressed. If you are not the intended recipient, you may not review, copy or distribute this message. If you have received this email in error, please notify the sender immediately and delete the original message. Neither the sender nor the company for which he or she works accepts any liability for any damage caused by any virus transmitted by this email.
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