Heat recovery chillers

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Has any one used the heat recovery option for an air cooled chiller? I am trying to reject heat to the heating hot water loop. Ive set this up as the heat receptacle. It appears to be working but the savings are unrealistically small. Only 6 therms a year.

Charles (Jason) Land

Charles Land's picture
Joined: 2011-09-30
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Check the design temperature and delta T of the loop to which you are trying to recover the energy. If the return water temperature is higher than the available energy from the chiller, no energy will be recovered. I?ve modeled this process for pool heating (much lower supply temperature) and the results were reasonable. Also check the maximum recover temperature on the Loop Attachments tab of the chiller. By default it is set to 105?F. I believe the highest is 120?F. Search the help for MAX-RECOVER-T for more information. This is also where you will want to define and attach a heat recovery pump if you have one. That way it will cycle on and off when the system can/can?t recover heat.

Also try to put the hot water loop on a reset schedule (as long as it is in line with the design). The lower the return water temperature, higher energy recovery availability.

If all else fails, run an hourly report that shows chiller state (on/off), recovered heat and loop temperatures to begin troubleshooting.

John T. Forester, P.E., LEED AP

jforester's picture
Joined: 2010-12-21
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Does ANYONE know how to turn off the annoying refreshing (I call it "dot
painting") every time I move or add a point in either the Custom Shell or Custom
zoning feature in the Wizards? It's like your Mother constantly reminding you to
brush your teeth !!

John Aulbach

John Aulbach's picture
Joined: 2011-09-30
Reputation: 1

Hi John,

If you mean the way the drawn shapes seem to quickly disappear/reappear
(white background) a single time when making a shape/vertex... I guess
I've never found that terribly annoying, but perhaps I've got an unusual
tolerance growing up watching epilepsy-inducing television?

On a serious note - you can definitely reduce any actual eyestrain from
this 'feature' and in general computer use by lowering the brightness on
your computer screen. I've read quite a bit into the subject (my MS
thesis was related), and the relative level of ambient light incident
from other surfaces in your field of vision while working on the
computer is pretty important, especially for those of us who might
intuitively crank the brightness/contrast way up on our
televisions/computer monitors to maximize the "punch" of image colors or
try to make up for lost eyesight over the years.

For less eyestrain, try out the following:

1. open up something with a white background (the email you're
reading right now will be okay) and try to fill the screen with the
white source.

2. hold up a sheet of white paper next to your screen under
ordinary working lighting conditions,

3. lower your screen brightness until the white area on the screen
surface is (subjectively) delivering about as much light in your eyes as
is reflected from the piece of paper

4. Optionally: if you work in a dim environment and/or have
shadowy dark surfaces around your monitor and/or simply can't lower your
screen brightness that much - consider some task lighting to add some
light to the surfaces around/behind your screen

5. make adjustments to eliminate any direct reflections from light
sources, especially if you have a glossy (specular) monitor surface

6. Optionally: if you've got a workspace with lots of daylight
(congrats on the corner office, you dog!), try to position your
furniture in a fashion so daylight from the outside world isn't in your
field of vision while working on your computer, again avoiding any
direct reflections

These measures may or may not reduce the "annoyance factor" depending on
whether it's really an eyestrain issue or you simply have OCD =). Note
that changing settings like this can take a little getting used to -
just like a pair of new shoes - but rest assured your eyes will thank
you in the long run!

If your "dot-painting" problem is more like a constant-refreshing,
that's something I don't think I've seen in any recent projects - you
might try reducing the size of the zone definition window on your screen
or perhaps an uninstall and clean reinstall of eQuest to see if that
alleviates the issue...



Nick-Caton's picture
Joined: 2011-09-30
Reputation: 805

John, seems like you are referring to the grid (black dots) in the
background of Custom Building Footprint and Custom Building Zoning
screens. If so, you can turn it off by selecting View Properties button
and then un-checking Show Grid box as shown on the screenshots below. I
always turn off grid display and snap when tracing drawings - it only gets
in the way.


Maria Karpman's picture
Joined: 2011-09-30
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Does anyone know of any advanced classes that are available for eQuest?

James M. Newman, EIT, LEED AP

James Newman's picture
Joined: 2011-09-30
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All I ever hear about are the beginners classes. If there are any advanced classes out there I would like to know as well.

Charles Land's picture
Joined: 2011-09-30
Reputation: 0

I've been in discussions with those who make a business of eQuest/DOE2
instruction regarding this issue... I think a major reason we don't see
many 'advanced' classes is: it would be very hard to develop a
rubric/syllabus for an 'advanced' group of learners as it would seem
there aren't many 'advanced' topics that aren't extremely
system/project-specific (therefore seemingly of little interest to a
group of learners at large).

One exception that comes to mind that would probably be of common
interest might be the evaluation and creation of chiller & heatpump
performance curves - that skillset is frankly tough to self-learn (it
took me a long while and multiple projects)...

As an aside: I might also cite a real-world experience where a local
rep for Carrier hosted an event that included discussion/instruction for
a single, narrow 'advanced' eQuest topic: geothermal well-field design
using eQuest/DOE2. The room was packed*! I hope more equipment reps in
time will recognize the value and potential draw when advanced eQuest
topic instruction is offered, even if only for a very narrow sort of

If you really would like formal, 'advanced' instruction, you might be
best-advised to come up with a list of topics you want
instruction/guidance on (make your own personal rubric), and share that
list either publicly on the lists or directly with those who offer
training services - you may be able to then filter out who is able and
is willing to teach you some or all of your desired instruction
individually, and at what cost.


* I would be remiss to not mention Anthony Hardman (frequent contributor
to these lists) provided that instruction, and it was excellent.


Nick-Caton's picture
Joined: 2011-09-30
Reputation: 805

Since Nick so kindly put the first few ideas on the table for what should be offered for advanced training (Thanks Nick!) I thought I would second the custom chiller and heatpump curve but also add that an advanced course on the refrigeration version of DOE2.2/eQuest would also be useful. Owners of refrigerated facilities don't want to be left in the cold (pun definitely intended) when it comes to LEED but simulation tools are difficult to find and use for that industry. Compressor curves would need to be on the topic list since watching a colleague struggle for weeks to get the right curve setup and operating for a project, only to have the owner change equipment vendors a week later.

Jeremy R. Poling, PE, LEED AP+BDC

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Joined: 2011-09-30
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I also find the "dot painting" to be very annoying and awfully time
consuming as on my system it seems like the dots refresh 2 or 3 times
every time I pan around. At first, I also got rid of this problem by
unchecking the "Show Grid" box, as Maria described. However, I noticed
that if I move the scroll bars, the dots reappear and the box is
magically rechecked. Zoom in or out, and they're gone again. It's a
weird behavior that I figured to be a glitch in eQuest. My solution was
to set the grid resolution to a large number, say 30 feet. This way,
even if the dots do reappear, it's basically an instantaneous refresh as
there are so few of them. You won't even notice they're there.

Jason Kirchhoff

Jason Kirchhoff's picture
Joined: 2011-09-30
Reputation: 0

Yep-- I make it habit to change my grid resolution to 10 ft when I start all
my models because since I know I won't need to snap to any grid points who
cares if I see them or not (because I have my p-line take-off to snap too.)

This is how I had resolved the 'dot painting' problem the first time I was
trying to input a 500,000 ft2 building with a 3ft grid resolution-talk about
epilepsy-inducing stimuli...

Jason's answer is right. John-you will feel back to normal after this. ;)


Pasha Korber-Gonzalez's picture
Joined: 2011-09-30
Reputation: 600

The topic I consider advanced is modelling
different floor plate shapes on each floor - with
a multi-storey atrium in the middle. The atrium
has corridor catwalks for crossing from one side
of the building to another. Supply air is
transferred into the atrium from the surrounding
spaces - the atrium is a return air plenum for multiple air handlers.

I would gladly pay for a step by step tutorial on
setting up the geometry for such a building.

I think a major reason we don?t see

Chris Jones

Chris Jones's picture
Joined: 2011-09-30
Reputation: 0

It may be of value to transition some of this advanced modeling discussion
towards a webpage where we can collect these step by step tutorials, as
Chris mentions, to build our communal knowledge base. Again, circling back
to the idea of a knowledge community like onebuilding, in lieu of a

NYCCTgreen's picture
Joined: 2011-09-30
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It is pretty bare at the moment, but here is the the IBPSA Wiki:


Michael J. Smith, EIT, LEED? AP

Smith, Michael's picture
Joined: 2011-09-30
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Is the IBPSA wiki something our onebuilding group can start to populate? Is
it open source and accessible? There is a lot of talent here the wiki can
benefit from.

NYCCTgreen's picture
Joined: 2011-09-30
Reputation: 0

Another users forum that was proposed a couple of months ago is www.esimforums.com. It seems to already be very organized and if users remain as professional there as they do on this mailing list, it can become a complete resource for eQuest modelers. There is a reluctance, for one reason or another, to change from this mailing list to any of the proposed wiki/forum options that have come up recently. It?s nice to see more and more people interested in creating a knowledge-base that is user friendly though. Perhaps there is a way to merge the existing with the new.


John T. Forester, P.E., LEED AP

jforester's picture
Joined: 2010-12-21
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Hi Chris,

Some running thoughts you might consider - all this in concert might get
the job done, in any case it's what I'd try first:

- Varying "floorplates"/zoning for each floor means you need
unique shells per floor, which means you can't use any of the
"open-to-above/below" approaches to making an atrium with the wizards.
That simplifies the discussion somewhat: you'll need to define this
atrium somehow "manually."

- I would draw out the "catwalk corridors" (assuming they're
covered and separately conditioned) on their respective shell-floors.
If they're open to the atrium I'd ignore them entirely.

- I would finish everything up in the wizards, and upon
entering detailed mode delete every created space/zone that's part of
the "atrium," excepting the top level's, which should include any
roof/skylight surfaces and be retained. Delete any child surfaces
associated with these atrium zones excepting any interior partitions to
the perimeter zones - if those exist, move the interior partitions to be
a child component of the appropriate perimeter zone first before
deleting the atrium zone. You might be above to avoid this scenario in
the wizards by defining the atrium zones LAST at the custom zone
definition dialogs for each shell... not sure but worth a shot.

- I would modify the space geometries (volume) and its internal
loads (# of people should account for the catwalks if they're open) to
match the full volume of the atrium

- Assign a SUM system as a placeholder to the atrium - goal
being to have all its loads handled by the systems serving the perimeter

- I would use the 2D view of each shell to modify all internal
walls "open" to the atrium in the actual design to be of type "AIR,"
and to simultaneously ensure their parent space is associated to the
large, common atrium space. I think this will correctly tie the
atrium's internal loads to the others thermally... this is why we took
care to keep those and not delete them along with the wizard-generated
atrium spaces.

- I would use the "DIRECT" option for the HVAC systems' return
air path, rather than the plenum/duct options - I think this will
indirectly ensure the heat gains/losses of any atrium skylights/roofs
and the collective internal heat gains in the atrium find their way into
the return air stream

I can't say 100% whether this is all you'd need to do, but it's a game
plan I would start with. To make a comment regarding accuracy: It's
probably fair to say eQuest, which doesn't model complex CFD on an
hourly basis, may not be as accurate in any end-case as some more costly
software options may be for a large atrium as you're describing. This
approach should be sufficient however for getting into the right
ballpark, provided those "think" items above hold true (you might want
to hold off for others' input).

Best of luck - sounds like an interesting project to say the least =)!


PS: I've never been compensated for my advice on these lists, and I'm
not about to start asking, but neither have I taken on any liability or
promise of availability as a formal instructor... That said, I wouldn't
go home and cry myself to sleep if someone found anything valuable
enough to compensate ^_^.


Nick-Caton's picture
Joined: 2011-09-30
Reputation: 805


Great input. I am curious how deletion of atria zones in ddedit compares to
the multi-level space zone characteristic option while you are creating
geometry. There is an allowance for gain assignment to only zone-lower


NYCCTgreen's picture
Joined: 2011-09-30
Reputation: 0

What you're referring to is something I brought up in my first bullet -
these these wizard-level atrium options, useful as they may be, are
limited in application to multi-story shells. If you need to define
unique zone maps (or 'floor plates') for each level, then you're stuck
defining unique shells for each level, which means you can't pursue
those automated atrium options.

If the simplification could be justified (the same zone map / "floor
plate" could be applied to each level) by the project's geometries, then
I'd happily scrap the process below in favor of using the wizard
features to define a multi-story atrium - it'd be much less work, though
the system-side coordination/analysis would still be necessary.



Nick-Caton's picture
Joined: 2011-09-30
Reputation: 805

Check out the website
See "Proj-3 -eQ-Tutor - Odd-Sides -Shell-Atrium - %Glass-DL" on the first page "Website Contents". Details of the project are under the tab "Proj+eQUEST". Select project "P3-Odd-Shape". The building has 3-level atriums for 30 typical office floors. Modeling was with eQUEST Design Development (DD).
See "Proj-13 -eQ-DOE21E - High-Rise-Multi-Use-Bldg" on the first page "Website Contents". Details of the project are under the tab "Proj-Bldgs" select "P13-High-Rise-Bldg". The typical office floors have 3-level atriums on the corners. Modeling was with eQUEST Design Development (DD) and Detailed Edit (DE). The main analysis comparing the heating costs of using Electricity and Natural Gas in Chicago was done with DOE2.1E
Both cases are based completed building projects.

Varkie Thomas's picture
Joined: 2011-09-30
Reputation: 0


I just checked myself as I haven't tried the wizard atria options
recently - it appears I was wrong and you can "multi-level" + "open to
below" options for single-level shells representing floors above the
ground level, provided you use the "immediately above" option to locate
those levels. The conditioned height defined for the first level of the
atrium determines the final space height, but also the height of the
associated roof surfaces - kinda wonky end-results if those are in the
middle of the building (roof would be shaded for the most part)...

It also appears a changing atrium shape doesn't prevent surface
intersections/overlap from occurring... Partitions are not created for
spaces adjacent to an 'open to below' space, with an end-result being
the only "thermal tie" between the atrium and the other zones would be
at the first level.

End-results seem inconsistent depending on what options I choose, and
I'm unsure whether the overlapping/intersecting surfaces generated may
have stability implications down the road for a complex model, so I'm
hesitant to recommend this route without others' approval... does anyone
else have recent experience with the wizard-level atrium options have
thoughts to share?



Nick-Caton's picture
Joined: 2011-09-30
Reputation: 805

Thanks Nick!
Re the catwalk - they are open to the
atrium. The one reason to model them is because
they have light fixtures associated. Including
the floor areas of the catwalks increases the
baseline lighting to capture the lighting of the catwalks.

The atrium is not open to the rest of the
building except by door. Between the perimeter
spaces and the atrium is glazing.

The other question I have is what do you do when
the floor plans are submitted in PDF - how do you
import the floor plans into equest? Or do you
have to enter all the vertices manually?

Thanks again for taking time to respond.

not sure but worth a shot.

I think a major reason we don?t see

Chris Jones

Chris Jones's picture
Joined: 2011-09-30
Reputation: 0

Send the PDF to your background in AutoCAD (This step depends on what
software your computer has installed), correctly scale the pdf and trace
the floor plan in AutoCAD.

Otto Schwieterman's picture
Joined: 2011-09-30
Reputation: 200

Are there other less expensive alternatives to AutoCAD?

Chris Jones's picture
Joined: 2011-09-30
Reputation: 0

No prob!

Whether you model the catwalks explicitly or not - consider you could
account for their people/light/other loads by simply adding those to the
common atrium space. The catwalks may initially make your LPD inputs
easier, but they might complicate the manual deletion/surface assignment
process I outlined by creating more surfaces for you to consider during
space deletion and surface assignments.

Also note I corrected myself and if your atrium shape is quite regular,
you may be able to use the wizard atrium inputs (open to below/open to
above) provided you use the "immediately above..." shell placement
option for floors 2 and up. It's probably worth experimentation as this
could ultimately be a great timesaver. You access these options by
double clicking the zone map image on the bottom-left of the DD wizard
zone definition screen. Note the zone shape at the ground level seems
to determine the projected roof shape at the top level - you may need to
define separate zones to account for the actual geometries.

Ultimately, the approach that makes the most sense to you is the right

I would not skip over Varkie's advice to check out the completed
reference models at bepan.info. The concept of partitioning a new
atrium zone every couple floors may do a better job of "layering"
unconditioned/semi-conditioned spaces, and depending on where your
return air is drawn that may be a more-accurate approach. You might
pick up some other useful ideas.

There are some software tools out there which will convert *.pdf to
*.dwg/*.dxf, but in my experience the end results are never perfect and
would require manual tracing regardless for eQuest. I'd second Otto's
advice to simply trace in AutoCAD or other tool of choice (I also use
Sketchup) using the PDF as a direct reference. That said, it's way
better to push your sources to give you a real CAD reference if it can
be made available.



Nick-Caton's picture
Joined: 2011-09-30
Reputation: 805

Hi Chris,
For a freeware CAD program I use DraftSight by Dassult Systems. (google
it) Only CAD files of type .dwg or .dxf can be read with the eQuest
viewers. You an also input your building points in the (x,y,z) coordinates
and its not too difficult, just tedious.

As far as my Atrium modeling experience goes, I've always used the Wizard
inputs to best define it in my models. I'll share what my experience
has been in using it and verifying its correct representation.

I have used the wizard level atrium options several times and like them
quite well. although I can't really tell you what I like about them...In
the basic sense, when I click the check box in the wizard to say
"multi-level space" or "open to below" it makes me feel like eQuest is smart
and I really am 'successfully' representing an atrium in my model. This is
all 'feel' good stuff in which I appreciate the wizard for offering those
feelings of comfort in my building my models.

Now in reality, DOE-2 cannot properly represent thermal characteristics of
atrium spaces and exchange of airflows. It does represent a good static
time-shot of load conditions in the atrium spaces for example. There can be
no exchange of airflows between multi levels of spaces (i.e. stack effect)
when using the "open to below" definition of spaces.--Thus, this has been my
experience with the wizard and DOE-2 atrium options:

- I have used different shells above and below with differnt zoning and
size of the atrium levels. Yes, it is possible to tell an atrium zone of
odd size "open to below" in the wizard, but in DOE-2 nothing really happens
or changes, except that there is no internal-floor construction that is
applied between these spaces.
- Be mindful in the wizard inputs that when you indicate a space is a
"multi-level" space it will ask you for the height of that space, and it
takes that zone to a different height from the original floor-to-floor
height that you input for your shell. The atrium should be specified at the
bottom floor zone and then input the full height of the atrium (which should
not exceed the height of the shell.) The internal load inputs for all of
your atria space(s) are specified in the wizard screen also including
occupants, lights, and plug loads. It will allow you to represent how much
of the loads (%) are in the occupied/conditioned area of the atrium vs. the
upper levels.
- Now, you can also place another shell above the shell with the atrium
in it and indicate "open to below" for the 2nd shell above the atrium
space. this function treats the upper zone (2nd shell) as a separate zone,
but still 'open-to-below' for the atrium space. If using this approach, be
mindful of the internal load inputs you have in the upper zones. You don't
want to simulate occupants "floating" above the rest and 'falsly' loading
your building model when they shouldn't be there.
- From this point, when you switch to the DDedit mode from your wizard
inputs you will see that your atrium is created as a single space/zone that
is a part of your Groundfloor shell, and the "core" zone is not duplicated
on the upper floors of the building shell.
- Considering the thermal perspective of this representation, it is
closer to accurate for a static modeling tool. At least the airflow within
the individual zone (atrium as a whole) is represented within itself, but
airflow exchange between adjacent zones cannot be represented in DOE-2.
This is more for dynamic simulation programs or even CFD modeling levels.
This discussion could take us on another tangent.
- If you are stacking more shells together and using the Multi-space
option on the bottom shell and then the "open to below on the other shells"
just be mindful of your internal loads for each zone. I think if you tell
the multi-level space that your atrium is the full height (extending its
height beyond its own shell) you might be able to get away with this
approach too, but you will probably have to delete the 'duplicate' spaces
that will be created in the upper shells. But I haven't verified this
because I don't know what other implications might come into play. The
DOE-2 info defines the atrium spaces as only being able to be the height of
the shell (not higher), so I wouldn't push my luck trying the last strategy.

Hopefully that will be a bit helpful to you, I had to learn it all by trial
and error and testing of my inputs and outputs. It's good to create a dummy
model and just try different things in the file to see how it can best
represent your project design. Always get someone else to review your
results as well to make sure they are logical.

Good luck,

Pasha Korber-Gonzalez's picture
Joined: 2011-09-30
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