Hi guys/gals-- it's been a long time since I've posted, mainly because its
been a loooong time since I've been working on energy models.
My skills might be a bit rusty, but you never forget how to 'ride a bike',
truly...
I would like some help with trying to figure out why my hours out of
throttling range are coming in like they are-- I've managed to reduce them,
but they are not in compliance for the LEED review yet. And I have
virtually "peeled" back all of my design inputs in the HVAC systems
(specifically for AHU-15) where the problems are occurring.
Can any of you please help me to take a second look at my file and see if
you can find what aspect of the inputs are pushing out my throttling
hours? I appreciate any insight/info/time you can provide, The attached
file is in a cold Michigan climate, it has a college schedule, and basic
loads with LED lighting system, so nothing internal should be pushing the
loads and controls out of throttling range. I'm available to chat about
this if any of you would like too. Ph 308-763-1593.
I've been struggling with getting the hours in range for a few months
now... please help. Thank you!
Hi Pasha,
The unmet load hours are coming from AHU-15. I noticed the following items that may help you debug the issue:
1. The SS-R report indicates that the zone L2ComputerLabZone is within the 100+ part load range for 8760 hours/yr. This is causing AHU-15 to not be able to reset its supply air temperature which means you are doing a lot of simultaneous heating and cooling in the other zones, especially at the perimeter. This could reduce unmet load hours and it will also reduce energy use if you put that zone on its own single zone system.
2. You are using the Powered Induction Unit system type but have all of the zone terminal types set to Std VAV Terminal. You should set any perimeter zones to either Series or Parallel PIU terminal type. This will allow those zones to pull induced air from warmer core zones with the Std VAV Terminal terminal type. Note that if you want to keep L2ComputerLabZone on AHU-15, applying the correct terminal types may help also since that zone will have excess heat to share with other zones.
3. You set OA ratio at the system level of 0.22 but the SV-A report states 0.454. If the correct value is 0.22, then you need to reduce the cfm/person OA input found at the zones because these will override the system level OA ratio.
4. You might want to check that the supply airflow and design cooling supply air temperature and zone reheat delta T are sufficient for the loads. You are hard coding the supply airflow at the system, it might be helpful to set it at the zone if you know the required airflow per zone (I?ve found that eQUEST doesn?t do a great job at distributing airflow to the zones sometimes).
5. Switching the zone thermostat type to Reverse Action from Proportional helps also (I did a quick test and overall unmet hours went from 65 to 55%).
6. SS-O report seems to show more unmet heating hours in the morning, therefore it may be worth revising the fan schedule to include up to 6 hours of optimum start period (use a value of -999).
Good luck.
Alex Chapin PE, BEMP, LEED AP BD+C, O+M
Energy Engineer | Mason & Hanger
A Day & Zimmermann Company
O 804.521.7072
4880 Sadler Road, Suite 300 | Glen Allen, VA 23060
masonandhanger.com
An ISO 9001 Certified Company
Building a More Secure World ?
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Hi Alex- This is great, thank you! I appreciate your help and taking time
to review my model details. I've been stuck on this file for a few months
now and my enthusiasm is nill, now. Thank you 1000x
Regarding your feedback, I'll jump on your suggestions today and check
things out.
I had previously (up until yesterday) been running the AHU as VAV, but
decided to throw it over to PIU to see if that helped with anything. I had
also been running the T-stats as Reverse Action (system default), but in
the warnings the notes suggested the proportional control so I had switched
that too-- so weird that you were able to see a reduction in the throttling
hours when you changed it. Are you by chance running your eQuest version
is DOE 2.3 mode? I typically haven't been running my files with 2.3, so if
you are doing this I will switch my program to see how this aids me.
I appreciate your insight on the OA ration value at the system level, so I
will make those adjustments at the zone CFM/person. I also appreciate and
agree with what you stated in item 4 about the zone level airflows, My long
past experience also showed that eQuest doesn't properly distribute
airflows from the system level, so I will go back and adjust my inputs
properly zone by zone (of course I was being 'lazy' when I set this up and
trying to hit the target with a fast & swift approach). Thank you for the
insight and "nudge" to do things right. LOL
Item 6- good idea on the fan schedules... I know at some point last year I
think I had set the fan schedules to -999 operation, but I remember
changing them back to on/off scheduling when I was trying to force a
balance in the model file.
I know it sounds funny, but it is fun to receive feedback and help from our
fellow eQuest modelers, so again Thank you--- our little isolated eQuest
'islands' that we work on sometimes get so lonely and makes us crazy! LOL
I'll let you know how these adjustments work.
Have a great day.
Pasha Korber
ph 308-763-1593
On Wed, Jan 13, 2021 at 7:14 AM Chapin, Alex N <
Hi Pasha,
I?m glad that I can be helpful. Hopefully you can figure it out.
I used eQUEST v. 3.65.7175 in DOE 2.2 mode. I normally use DOE 2.3 mode for my projects but I switched to 2.2 mode since it seemed like that?s what the file was based on.
I agree that it is tough being on your own little eQUEST ?island?. That?s why I try to contribute to this email list when I can.
Thanks,
Alex
Alex Chapin PE, BEMP, LEED AP BD+C, O+M
Energy Engineer | Mason & Hanger
A Day & Zimmermann Company
O 804.521.7072
4880 Sadler Road, Suite 300 | Glen Allen, VA 23060
masonandhanger.com
An ISO 9001 Certified Company
Building a More Secure World ?
CAUTION - THIS EMAIL MAY CONTAIN CONFIDENTIAL INFORMATION
This electronic mail transmission and any accompanying documents may contain information belonging to the sender, which may be proprietary, confidential, and/or otherwise subject to restrictions on disclosure beyond the intended recipient. This information is intended only for the use of the individual or entity to whom this electronic mail transmission was sent as indicated above. If you are not the intended recipient, any disclosure, copying, distribution, or action taken in reliance on the contents of the information contained in this transmission is strictly prohibited. If you have received this transmission in error, please call 1-703-955-5702 and delete this transmission. Thank you.