Heating Hours Unmet

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Equesters,

I have a packaged single zone system using DX cooling and Furnace heating
that serves 7 different zones and is controlled by the corridor zone. This
is supposed to replicate "System 3" in ASHRAE 90.1 appendix G. I have many
unmet heating hours (including my system control zone). I have let eQuest
auto size equipment capacities and and cfm. I have tried doing everything I
can think of to reduce the number of unmet hours. My OA volumes are pretty
small and shouldn't be affecting it. I expected possibly a few unmet hours
in some of the zones, but not in my control zone, the corridor, and not to
this magnitude. I get the following warning message seen below, I'm not
sure what it means by "Baseboard-Rating"? Any ideas on what this means or
how I could reduce the number of unmet heating hours?

**WARNING********************************************************************
**
ZONE EL1 Food Storage Zn (G.S2)
might have insufficient heating capability.
Check that the SYSTEM or ZONE HEATING-CAPACITY plus this
ZONEs BASEBOARD-RATING is adequate to maintain the ZONE
specified DESIGN-HEAT-T for the calculated peak ZONE load
(see LS-A or LS-B for the ZONE peak load.)

Thanks for your help,

Kyle Nisonger

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Kyle,

Try this first: eQuest expects a single-zone system to serve just that -
a single zone. You'll need to have a separate single zone system
created for each zone you need to assign to that system. Once that is
done, eQuest will then be able to address the thermostats in each zone
adequately and you should see a rather dramatic drop in your unmet
heating hours, possibly eliminating them altogether.

After that, if unmet heating hours remain there are a number of other
things to look at. Let us know if the above works first.

JEREMY R. POLING, PE, LEED AP

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Kyle,
Like Jeremy says, if you are modeling System 3 in Appendix G then you
should have one system per zone (as described in the 90.1 User's Manual,
p.G-23). One thing to check for unmet heating hours is your zone
BASEBOARD-CTRL (assuming you have perimeter heating). Set it to
Thermostatic. If you try to satisfy multiple zones with one single zone
system, try changing the control zone, manually adjusting the supply
flow to individual zones, and/or setting interior walls to "Air" walls
where appropriate (such as for zones where air is supplied to one and
returned from the adjacent zone).
Regards,

William Bishop, EIT, LEED(r) AP

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In the DD Wizard, screen 23, it asks for the exterior lighting load in
W/ft2. Where is it getting the square feet to determine the Watts? Is
there a way to tell it how much area outside you're trying to light? If
not, why is there a W/ft2 input?

-Jason

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Jason,

I believe I tested that out once and the W/SF is the building exterior
wall area. I generally don't find this wizard screen all that helpful.

Jonathan M. Curtin, EIT, LEED(r) AP

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Where do you suggest I go to enter exterior lighting for a LEED project?

-Jason

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Jason,

You can create an electric sub-meter in the detailed edit mode.

-Jonathan

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To add exterior lighting, you can go to the Utility & Economics screen. Direct loads - exterior. Energy will show up as "Ext Usage" on the BEPS/BEPU reports.

William Bishop, EIT, LEED? AP

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Thank you to all, it makes sense now.

-Jason

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Jason,

I agree with Jonathan - this part of the wizard is not too helpful. I usually leave it set to the default and then when I am in the detailed edit mode I adjust it to the actual kW load for the design. If this is for an ASHRAE 90.1 Appendix G model, then I separately calculate the kW for the baseline model and input that.

The site lighting is tacked onto the meter in eQuest as a separate load with its own schedule. You'll need to adjust the total load there.

JEREMY R. POLING, PE, LEED AP

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I have assigned each zone it's own single zone system, but I still am coming
up with about the same number of unmet hours. I can manually adjust the
design cfm to lower them, but this seems futile trying to play around with it
to get it just right. Shouldn't eQuest automatically size the equip. and
cfm's to meet the load? Another question I have is why doesn't the percent
of hours outside of the throttling range on the BEPS report match up with the
number of unmet hours on the SS-R report? I have attached my project files
if anyone has time to look at them. I appreciate your help.

Thanks,

Kyle Nisonger

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Kyle:
?
We need the.INP file, not the -2.INP file. It also appears with that, you are running parametrics. We also then need the .PRD file as well.
?
John Aulbach

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John,

I've attached the two files you requested, but I don't think they are
necessary because my parametric runs only incorporate rotating the building
to meet LEED.

Thanks for your help, sorry for the confusion.

Kyle Nisonger

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Kyle:

Your unmet hours are all in the morning warmup in the cooler months.

You might try COINCIDENT for Sizing-Option.

The SS-R unmet hours agree with the "Air Side" HVAC Summary Tab, when you click on the tree Diagram to the left on the Project name. Why the BEPS has a different number is unknown to me.

I believe others need to take a stab at this..so I reattach your eQuest files for their perusal.

SIZING-OPTION
Takes a code-word that specifies whether the system's
SUPPLY-FLOW equals the sum of the zone flows (NON-COINCIDENT) or is based on the
peak block load (COINCIDENT). The reason that NON-COINCIDENT is the default is
due to the reduced lighting power and better window treatment that most
designers use today. If the number of hours with "loads not met" is too high
with SIZING-OPTION = NON-COINCIDENT, you should increase the air-side system
capacity by setting SIZING-RATIO > 1.0.
NON-COINCIDENT?????? SUPPLY-FLOW is sized using the sum of the
peak loads of the individual zones. (These peaks usually occur at different
times and are, therefore, non-coincident.)
COINCIDENT?????????????? SUPPLY-FLOW is sized using the peak
value of the sum of the loads of the zones on the system.

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