EQUEST QUESTION

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I am trying to learn E-Quest and I am trying to model a building that I
have already modeled with Energy Pro. The gas usage from E-Quest is
very very low compared to both actual and Energy Pro. It is a hot water
reheat VAV system with a boiler and a water cooled condenser. The
actual gas use is 17891 Therms, from the bills. Energy Pro predicts
17600 Therms. E-Quest predicts 580 Therms. This makes no sense to me,
but it is clearly my error. I have gone over the inputs several times.

Is there anything that occurs to anybody that would make gas usage that
far off?

Electrical from E-Quest is 453 MWh. Electrical from Energy Pro is 422
MWh. Electrical actual is 543 MWh. The building has lots of
unaccounted-for process equipment, so I'm not so worried about being low
on electrical. It's not too far off. But the gas use is just way too
low. Hot water is showing up at 3 Therms a month.

This is the first model I have done with E-Quest, so I apologize for
even asking. It's obviously something stupid that I have done.

Robert Wichert P.Eng. LEED AP

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I've always found the default plug & lighting loads in eQuest to be on the
high-side which has a significant affect on space temperatures and space
conditioning energy.

Chris Flood

Chris

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I would take a look at your unmet load hours in the perimeter spaces. If
they're high it's likely that you have a heating air flow rate or supply
air temperature issue.

Morgan Heater, P.E. BEMP, LEED AP

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You might want to take the online eQuest course from
http://energy-models.com/training/equest/course-objectives
I found it to be very helpful when learning eQuest.

I would guess your issue is occupancy differences, or deep in the HVAC
system like Morgan suggests..

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A quick thought: REHEAT-DELTA-T is a zonal input that has specifically caught me and others multiple times for systems with reheat. It's something that isn't optional for some systems, and doesn't have a default coming out of the wizards so you have to physically enter something (I typically right-click and enter stuff like this as a user-defined default - blue text - more in the archives if you're interested). If you leave the inputs blank the reheat won't engage.

If it's not that, efficiencies are relatively easy to check. I would scan your reheat and preheat inputs (if applicable) next: Right-click and review the DOES2 help entries under heat, reheat, and preheat (at the zones) for any inputs you've allowed to default/leave blank - you might just need to fill in one more box ;).

NICK CATON, P.E.

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Hello,
?
I would kindly ask for information please.
I am doing energy modeling for LEED EAc1 complinace in Energy Pro. It is a mixed use building (retail and residential). The HVAC system is as follows: ?for RETAIL: ?Unconditioned fresh air is supplied by roof mounted supply fan (SF) to the zone where? one portion is mixed with ?indoor air and ?introduced to the indoor unit of split electrically driven heat pump. The other portion of the fresh air is supplied around kitchen hood serving as an air curtain and?exhaust is by kitchen hoods. For residential - electrical baseboard heaters only + natural ventilation.
Corridors are not conditioned but just ventilated (fresh air supply + exhaust for each corridor per floor)
My?concerns are as follows?.
?
1) ?How to model retail HVAC system? One room is one zone.
My approach would be:
@ system level/Split DX/Heating and Cooling capacity of outdoor unit/ Enter fan cfm and HP for outdoor unit as per cut sheet
@ zone level/ zonal system/select variable refrigerant flow (just to account for heating and cooling capacity), enter heating and cooling capacity of indoor unit / fan tab enter cfm from ?fan cut sheet (mixed air)
@ room level/ exhaust fan tab/ enter cfm being exhausted (to account kitchen hoods)
?
How to model SF? Perhaps to include additional zone and room, where internal loads are zero, room is unconditioned with cfm and HP entered @ zone level? ??
?
2) How to model electrical baseboard heaters? One room is one zone.
My approach would be: @ system level , select any system without heating/cooling. At zone level, select e.g. VAV box and put Heating Output only.
?
3) How to model ventilation for corridors?. One zone includes corridors on several levels
My approach would be:
@ system level: select any system without heating/cooling, no input for fan
@zone level/ select e.g. VAV box or diffuser/ enter air supply cfm ?but without heating/cooling
@ room level/ exhaust fan tab/ enter cfm being exhausted
?
?Thanks,Sasa
?
?

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A follow up for Robert and others:

I recall Robert mentioning he's new with eQuest so my response was probably a bit cryptic, and I happen to have a model open and appropriate for illustrating what I'm talking about. This is a good opportunity to clarify my advice for reheat systems and share some more tidbits all eQuest users should be aware of.

Recognizing this is [bldg-sim], what follows is eQuest-specific procedure/advice geared for new/intermediate users:

REHEAT-DELTA-T is an input after the wizards and in detailed mode. It can be input for the system and/or for the zones served - where you define it is determined by the type of system you are using (right-click the input field and read the associated help topic for more details).

Navigate to the 'Airside systems tab' and then double-click on a conditioned zone (not a plenum) under a system in the tree on the left. From there, you can find the zone heating tab:
[cid:image002.png at 01CCFD08.F4822F80]

Alternatively, you can find REHEAT-DELTA-T for a system by double-clicking a system and navigating to the heating > Coil/Capacity tab. My advice below is that if you are seeing white boxes, then you may want to try entering something.

In a typical scenario, this number is added to the discharge temperature defined at the system level, indirectly defining the discharge temperature for your terminal boxes... In the example above I wanted the box to put out 100F heating air per the HVAC design, and the central unit was discharging 68F, so I arrived at setting a 32F delta.

I mentioned "user-defined defaults" / "blue text" as well: suffice to say that is something every intermediate/advanced user really should know about, but beginners can comfortably put off to learn later. It's merely a means of using the program more efficiently. Again, instructions are in the archives ;).

Finally, I and others will commonly say "read the help for that input" and I recognize this may not seem intuitive/easy given the massiveness of the DOE2 help file and how little is in the actual eQuest help file. This comes up often, so here's a quick visual of what some of us are getting at:

[cid:image001.png at 01CCFD1D.EBE00DB0]

Almost EVERY input field has a corresponding help entry in the various help resources that come with eQuest. You can most easily find them by right-clicking the field you want to learn more about for a context menu, then mousing over the first item: "Item Help" This will bring up one or more references that will bring you straight to something pertinent to what you're looking at, most of the time. All eQuest users are ultimately self-taught to some extent, and this way of using the resources at your fingertips is something not to miss!

Best of luck!

NICK CATON, P.E.

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