[Equest-users] Removing Unmet Hours?

Fri Oct 21 13:37:16 PDT 2016

Hi Kumar,

Responses below in red and tagged with [NC] for those who aren't seeing this with formatting.

There's some broader/overarching advice in the final paragraphs you might want to read first.

~Nick

[cid:image001.png at 01D22B78.1A765C00]
Nick Caton, P.E., BEMP
  Senior Energy Engineer
  Energy and Sustainability Services
  Schneider Electric

D  913.564.6361
M  785.410.3317
E  nicholas.caton at schneider-electric.com<mailto:nicholas.caton at schneider-electric.com>
F  913.564.6380

15200 Santa Fe Trail Drive
Suite 204
Lenexa, KS 66219
United States

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From: Equest-users [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Saurabh Kumar Srivastava via Equest-users
Sent: Thursday, October 20, 2016 10:41 PM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] Removing Unmet Hours?

Hey Guys!

I was just removing the Unmet hours from my Proposed and Baseline Models and have encountered a  few questions.
It would be really nice if you could let me know the correct approach!

Proposed Case
- As the Proposed building has District Heating (hot water via Steam Meter) there are a lot of Unmet hours (approx. 5000)
[NC] Caution: This doesn't make sense as a causality without further context.  District steam should be capable of heating a building to comfort.
Also observing: a magnitude of 5000 unmet hours (presumably all heating and coincident hours, by context) suggests you aren't delivering ANY heat through a full season, or perhaps your thermostats are asking for something unrealistic.

- To design the radiators I've use Baseboard heating with Control as Thermostatic.
[NC] OK.  I'd confirm in SV reports that you're getting reasonable capacities if you aren't already specifying - I've found the autosizing isn't always reliable and I have to hard-enter capacities at times.
- Increased the Min Air flow ratio in the Zones of the VAV system to almost 0.9
[NC] Pushing all terminal minimum airflows up to 0.9 sounds unrealistic to my experience for correctly applied VAV systems if you intend to model everything working properly...  It may be appropriate to raise the minimum for specific zones however exhibiting difficulties to help eQUEST distribute airflow when/where needed.  Inputs for min airflow and max heating airflow ratios at the system (central) fan should also be considered.
- Increased Throttling range to 5°R
[NC] This can be counterproductive to reducing unmet hours in some cases.  Rather than fiddle with this dial for a desired result, try to affirm and match actual controls/design.
- Increased Reheat Delta T to 35°F
[NC] d35 is within reason for reheat coils.  Better to confirm against coil design/selections, as it can vary, but I wouldn't be as concerned with this choice.
There is no restraint on the amount of heat the building wants.  Hence, I wish the building receives unlimited heating from the Hot Water(Purchased Heat),So whatever is the requirement ,it is sufficed by the Heating system.
This may lead to reduction in Heating Unmet hours.
Your LOOP-OPERATION input (typically) determines whether heating is restricted when it's called for by a system/coil (either due to temperature, scheduling, or some combination).  Sounds like you want DEMAND-ONLY or STANDBY, paired with a steam meter rather than a boiler.
1)How can I do this, to reduce the Heating Unmet hours?
[NC] I think you're asking how you can check your suspicions that the loop is not delivering heat when needed.

·         Firstly, you'd probably see a warning/caution to this effect in the ATTN report if this were the case.

·         Secondly:  Project & Site tab --> Create an Hourly Report --> Create a custom block for your HW loop (you might want to create a few if you have multiple HHW loops) --> select the result options (tickboxes) to report on hourly coil loads, flows, and any of the loop operation flags that may help complete the picture.  Also create a block to track your steam meter's output. --> Assign those blocks to the new report you made --> Close the hourly results dialog, simulate, then export hourly results (File, Export, Hourly results) --> You should be able to review exactly what's being asked for vs. what's being provided each hour of the simulation (I'd suggest doing some algebra to find & quantify any differences - consider pump heating contributions while you're at it).

Baseline Case : System 7
- As the VAV system is with Reheat, and the heating is through Hot water(Purchased heat).
1)Would it be right to Keep Baseboard Heating using Hot water on to counter Unmet hours?
[NC] I might consider this as a "band aid fix" if I were running out of time on a deadline, but relative to "fixing" airside delivery this is likely to be detrimental to your performance rating (energies associated with air movement and ventilation loads might be left unaccounted for).  You're better advised to strip baseboard heating out of your baseline and figure out how to get your airside heating operational.
Unmet hours is Approx 5000.
[NC] Sounds like you should fix your proposed case first and apply whatever changes are appropriate to your baseline - they're both "broken" in a similar magnitude.

- As per G3.1.3.12, The Min Air Flow ratio is to be 0.4
2)Can I increase it to counter Unmet Cooling and Heating hours?
[NC] Yes, but per above I would only advise this on a "spot" basis to address specific zones exhibiting unmet hours.  Typically these are cases where eQUEST's airflow sizing routines don't catch relatively high internal/skin loads for something like a corner office or corridor vestibule.

As the Project Deadline is 28/10/16. I really needed advice.
[NC] Block out any time you need for documentation to establish your "pencils down" point, and mark your calendar.  If between here and that point you determine you're not likely to make it, communicate that you need more time/help/resources to those that need to hear it inside your company.  Be advised there are independent consultants monitoring these lists & available for hire who could be a resource if engaged with enough time before your deadline to review and catch up on your development efforts to-date.

Focus on your Proposed case.  Save a separate copy, and take a moment to reverse (or reconsider/research) any arbitrary tweaks you've made so far in the name of making unmet hours go away (thankfully it looks like you're in a good habit of self-documenting such edits).  Your actual goal is to find and resolve the cause of the hours and those tweaks have a high probability of obfuscating the true causes.  Document your reasoning and edits to facilitate carrying those changes over to the Baseline model later.  My intuition/hunch is you need to carefully review where the unmet hours are occurring (everywhere? 1 or a few specific zones?).  Also review thermostat schedules and application (don't place thermostats where they don't exist) to be sure the calls for conditioning are reasonable.  Also review system fan schedules & operation to ensure they're responding to calls as they come.

Please Feel Free to add any suggestion or approach strategies! :)

Best Regards

Kumar

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