Hey everyone,
The hospital I am working has different footprints for each level (see snapshot below). While going thru the bldg. envelope in detailed mode, I noticed that the surfaces separating interior floors are modeled as exterior roofs. Now it?s been a while since I?ve modeled using eQUEST but I?m sure these surfaces should be modeled as interior floors.
So a couple questions:
1) What did I miss in the DD Wizard? One shell was made for each elevation, and for the each above grade floor, below is the input entered for the floor info. Is this where I made my mistake? Or do I need to model the shells with and without roofs separately?
2) Is there a fast way to change what?s needed without deleting each ?interior roof? and replacing it with an interior floor or going back into the DD wizard? Pretty sure not but here?s hoping!
Thanks everyone. Hope your mid-week is going well!!
Darryl Kasun
Hello Darryl:
It may be worse than you think.
From the looks of the image it also appears that you have plenums in the building, which further complicates the simulation, and for reasons that are not always obvious. For example, in DOE-2 if you declare the return air path as having a plenum and then assign the walls, roof, floor, etc. to that plenum as the zone, then the heat gain/loss from that surface is assigned to the air that is returning from the zone on its way back to the HVAC system and therefore, it will not show up in the peak load in LOADS because it is a heat gain to the return air and not the zone. You can prove this to yourself using the SAMP1 file that comes with DOE-2.
For example, in the SAMP1.INP file that comes with DOE-2, RUN 3A, there is a single story 5 zone model with a plenum. What you will notice when you run this model is there is no roof load in LOADS because the single story building has a plenum and the roof load has been assigned to the plenum as the zone. The load from the roof does show up when you assign a SYSTEM where it then appears as heat gain/loss from the return air.
To ?see? the load from the roof you have to remove the plenum and re-proportion the roof to the zone area. Then the roof shows up in the component loads in the LOADS peak load report.
I suspect that deep inside the bowels of the model you showed below this is going on.
Jeff
8=! 8=) :=) 8=) ;=) 8=) 8=( 8=) 8=() 8=) 8=| 8=) :=') 8=) 8=?
Jeff S. Haberl, Ph.D.,P.E.inactive,FASHRAE,FIBPSA,......jhaberl at tamu.edu
Professor........................................................................Office Ph: 979-845-6507
Department of Architecture............................................Lab Ph:979-845-6065
Energy Systems Laboratory...........................................FAX: 979-862-2457
Texas A&M University...................................................77843-3581
College Station, Texas, USA, 77843..............................URL:www.esl.tamu.edu
8=/ 8=) :=) 8=) ;=) 8=) 8=() 8=) :=) 8=) 8=! 8=) 8=? 8=) 8=0
Hello Darryl:
Yes, the heating/cooling loads should be showing up in the SYSTEMS reports. However, it will be in a ?lump? that does not allow you to separate out the individual components. You can switch it on/off by using the direct return option, but then this chops out those surfaces from participating in the simulation, depending on how you?ve linked up the plenums to the spaces in the next-to commands (or how the DOE2.2 robot does it).
You can see the loads in the plenums, but it will not show up in the UNMET loads because there is no thermostat in the plenum?hence no UNMET loads.
Jeff
PS: That?s off the top of my head?the eQUEST manual might shed more light on this.
8=! 8=) :=) 8=) ;=) 8=) 8=( 8=) 8=() 8=) 8=| 8=) :=') 8=) 8=?
Jeff S. Haberl, Ph.D.,P.E.inactive,FASHRAE,FIBPSA,......jhaberl at tamu.edu
Professor........................................................................Office Ph: 979-845-6507
Department of Architecture............................................Lab Ph:979-845-6065
Energy Systems Laboratory...........................................FAX: 979-862-2457
Texas A&M University...................................................77843-3581
College Station, Texas, USA, 77843..............................URL:www.esl.tamu.edu
8=/ 8=) :=) 8=) ;=) 8=) 8=() 8=) :=) 8=) 8=! 8=) 8=? 8=) 8=0
Hi Jeff,
I think I'm on the same page as you now. Let me give a little information
about this project just so I can assure myself I'm modeling this correctly.
I have the design drawings/specs for a hospital which using as the inputs
for the eQUEST model. The majority of spaces are heated/cooled/ventilated
by central AHUs with VAVs c/w reheat coils along the perimeter. If I model
the zones without plenums, do I not run the risk of seeing unmet loads in
the perimeter zones as the reheat coils may not be large enough for say the
peak heating load for that zone?.
Hi ,
I`m still learning e-quest
if you finish this project could you send as case study......I`m looking
for case study from A to Z could send to me as a link on drive
thanks in advanced
Hi Darryl,
From what I understand, your problem comes from the fact that when you specify a roof on a shell (Wizard, page 3), a roof is created for every zone of that shell regardless of what?s directly over the zone. In example, you can have a 3rd floor zone with a roof even though there?s another zone directly above it on the 4th floor.
Unfortunately, eQUEST does not make this ?check?.
To avoid this problem, you can of the following:
A. Model zones with roofs in separate shells than those without roofs
B. Manually delete the excess roofs in the detailed design phase and replace them with ceiling.
C. Model roofs only for the top floor and manually add extra roofs for those zones not on the top floor.
D. Assign insulation values of R = 10000 (eQUEST maximum) to the excess roofs.
Whatever option you choose, you might encounter some zones with partial roofs which might cause you some problems. Meaning the exposed roof of the zone doesn?t match the full footprint of the zone. This will net you weird zone patterns if you use option A. If you use option B or C you will have to create polygons matching the exact roof surface and model the roof using these polygons. If you use option D, you can create a construction R value based on the actual roof surface vs eQUEST modeled roof surface ratio.
Unfortunately I don?t think there?s a ?magic? solution. Each one has it?s upside and downside.
Hope this helps.
[Bouthillette Parizeau]
Patrick Lapierre_ing.
plapierre at bpa.ca
De : Equest-users [mailto:equest-users-bounces at lists.onebuilding.org] De la part de Darryl Kasun via Equest-users
Envoy? : 13 juillet 2016 15:42
? : equest-users at lists.onebuilding.org
Objet : [Equest-users] Modeled Interior Floors as Exterior Roofs
Hey everyone,
The hospital I am working has different footprints for each level (see snapshot below). While going thru the bldg. envelope in detailed mode, I noticed that the surfaces separating interior floors are modeled as exterior roofs. Now it?s been a while since I?ve modeled using eQUEST but I?m sure these surfaces should be modeled as interior floors.
[cid:image002.png at 01D1DDA3.CC3E0780]
So a couple questions:
1) What did I miss in the DD Wizard? One shell was made for each elevation, and for the each above grade floor, below is the input entered for the floor info. Is this where I made my mistake? Or do I need to model the shells with and without roofs separately?
[cid:image003.png at 01D1DDA3.CC3E0780]
2) Is there a fast way to change what?s needed without deleting each ?interior roof? and replacing it with an interior floor or going back into the DD wizard? Pretty sure not but here?s hoping!
Thanks everyone. Hope your mid-week is going well!!
Darryl Kasun
Whew!
You're making me think on a Sunday PM...which may not have accurate results...but here goes.
First, although this is painful, you can always "test" what you are doing by running w/ and w/o the plenums and see what shows up. To do this you'll be looking in the LOADS printout for the peak load by space, where it shows the magnitude of the different components, i.e., roof, opaque walls, etc. Unfortunately, this requires a whole-lot of reconfiguring of plenum walls, zone adjacencies, etc.
Once you have your system configured both wasys you can trace this through the system peak load, keeping in mind any duct losses that you put into the system and/or thermostat settings (probably best to use SYSTEM = SUM), depending on how you configured your ductwork. You will also be able to see the peak loads for the roof versus =0 for the roof when you have a plenum between the drop ceiling and the roof above. Of course, all this depends on whether or not you've switched on return = plenum. If you haven't then you shouldn't see any difference if you're using return = direct, or something else.
Second, I suspect even if you do see something, and you're still worried, you need to pay attention to the magnitude of the peak cooling and/or heating contribution by the component relative to the other components. For example, windows of any size usually overwhelm other loads.
Third, in regards to your perimeter zones, the loads from any plenum will mostly have an impact on the top floor and not the in-between floors if the zone temperatures are the same between floors. Especially, if you are using multipliers, which further complicates things.
That should give you something to chew on for now...and I can't really shouldn't go much further without looking further at your design in detail.
Jeff
PS: I'll be teaching a DOE-2 class in the fall if you interested in taking it at a distance via an ON-LINE link.
Jeff S. Haberl, Ph.D., P.E.inactive, FASHRAE,FIBPSA
Department of Architecture
Texas A&M University
College Station, TX 77845-3581
Office: 979-845-6507, Lab: 979-845-6065
Fax 979-862-2457
jhaberl at tamu.edu,www.esl.tamu.edu