[Bldg-sim] Double Facades - EPlus
kiran kumar
kirankumar.devs at gmail.com
Thu Mar 24 21:49:32 PDT 2011
Hi all,
Can anyone suggest the best tool to model double skin facades with glazing?
Kiran
On Thu, Mar 24, 2011 at 2:01 AM, <bldg-sim-request at lists.onebuilding.org>wrote:
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> Today's Topics:
>
> 1. Re: Difference in chiller energy for VAV and CAV system
> (Nick Caton)
> 2. Re: Double Facades - EPlus (Pedro Peixeiro)
> 3. Corporate Deduction, comparison of the proposed design with
> the baseline design by ASHRAE 90.1-2001 (Evgenia Gorbachinsky)
> 4. Re: Corporate Deduction, comparison of the proposed design
> with the baseline design by ASHRAE 90.1-2001 (Deru, Michael)
> 5. Re: Corporate Deduction, comparison of the proposed design
> with the baseline design by ASHRAE 90.1-2001 (Robert Gengelbach)
> 6. fully funded PhD position at TU Eindhoven (Hensen, J.L.M.)
> 7. 90.1 Appendix G - Resizing Baseline Systems to Meet Unmet
> Load Requirements (G3.1.2.2) (Kerry Gorczynski)
>
>
> ---------- Forwarded message ----------
> From: "Nick Caton" <ncaton at smithboucher.com>
> To: "Aaron Powers" <caaronpowers at gmail.com>, "Deepak Tewari" <
> dipaktwri at yahoo.co.in>
> Date: Tue, 22 Mar 2011 16:18:42 -0500
> Subject: Re: [Bldg-sim] Difference in chiller energy for VAV and CAV system
>
> I too cannot claim to be capable of tearing a chiller apart and putting it
> back together, but I can affirm Aaron’s fundamentals appear on-cue to my
> understanding. Less cooling à less compressor work à $$$ savings.
>
>
>
> The attached email exchange from a few months back may be of interest to
> those following/participating in this discussion, though it is a bit
> lengthy. In it, I attempt to “reverse engineer” the three default curves
> found in eQuest/DOE2 which together define behavior of a centrifugal
> chiller, observing and discussing the isolated effects of all the variables
> that are taken into account on an hourly basis… One following along can see
> I was a bit puzzled along the way, but arrived at an “ah-ha” moment when I
> followed through and applied the curves against each other to observe their
> net effects on efficiency under set conditions.
>
>
>
> My hope then and now is that sharing this thought process may help others
> arrive at their own “eureka” moments =).
>
>
>
> ~Nick
>
>
>
> [image: cid:489575314 at 22072009-0ABB]**
>
> * *
>
> *NICK CATON, E.I.T.***
>
> PROJECT ENGINEER
>
> Smith & Boucher Engineers
>
> 25501 west valley parkway
>
> olathe ks 66061
>
> direct 913 344.0036
>
> fax 913 345.0617
>
> www.smithboucher.com* *
>
>
>
> *From:* bldg-sim-bounces at lists.onebuilding.org [mailto:
> bldg-sim-bounces at lists.onebuilding.org] *On Behalf Of *Aaron Powers
> *Sent:* Tuesday, March 22, 2011 2:41 PM
> *To:* Deepak Tewari
> *Cc:* bldg-sim at lists.onebuilding.org
> *Subject:* Re: [Bldg-sim] Difference in chiller energy for VAV and CAV
> system
>
>
>
> Bill, you're right about that. A central CAV system with reheat is limited
> by the most loaded zone. My statements before were simply for one air path
> and one zone, which is probably rare. The degree to which this hurts a CAV
> system depends on the diversity of the loads. If all zone loads remain
> similar, then the supply air temperature off the CAV coils will start to
> float upwards at reduced loads, and you'll see an increased chilled water
> delta-T.
>
> As for the increased chiller efficiency, here's my thinking. At a constant
> load with no mixing valves, an increased delta T across the cooling coils
> allows for a lower gpm. Slowing the water flow rate and raising the
> entering water temperature increases the effectiveness of the evaporator
> barrel (i.e. the enthalpy of the refrigerant now has a greater ability to
> approach the enthalpy of the higher enthalpy water). Running the compressor
> as before would over-cool the water. To maintain a constant chilled water
> supply temperature, the mass flow of the refrigerant must be reduced.
> Depending on the type of compressor unloading mechanism, this should produce
> some energy savings.
>
> This is my understanding simply based on theory, and I'm sure it's much
> more complicated in reality. Again, I know that DOE2 does not account for
> varying inlet conditions to the chiller evaporator barrel, but I'm not sure
> about ePlus.
>
> Aaron
>
> On Tue, Mar 22, 2011 at 5:30 AM, Deepak Tewari <dipaktwri at yahoo.co.in>
> wrote:
>
> Aaron
> Can you elaborate how the larger chilled water delta-T will decrease
> chiller lift and increase efficiency?
>
>
>
> ------------------------------
>
> *From:* Aaron Powers <caaronpowers at gmail.com>
> *To:* "James V Dirkes II, PE" <jvd2pe at tds.net>
> *Cc:* Deepak Tewari <dipaktwri at yahoo.co.in>;
> bldg-sim at lists.onebuilding.org
> *Sent:* Mon, 21 March, 2011 8:41:21 PM
> *Subject:* Re: [Bldg-sim] Difference in chiller energy for VAV and CAV
> system
>
>
>
> There are several things going on here:
>
>
>
> - Yes, the lower fan energy for VAV will add less heat to the chilled water
> loop. This will propogate to the pumps, chillers, and heat rejection.
>
> - Chilled water coils are complex heat-exchangers, which do not exibit
> linear behavior. Reducing the air flow decreases the water-side coil
> effectiveness; therefore, at a given load, a CAV system will have a larger
> chilled water delta-T.
>
> - With equivalent pumping schemes, this will result in pump savings for the
> CAV system (in the absence of 3-way valves). I'm not sure about ePlus, but
> this can be demonstrated in the latest DOE2.2.
>
> - In reality, the larger chilled water delta-T will decrease chiller lift
> and increase its efficiency. Again I'm not sure about ePlus, but in DOE2.2,
> chiller curves are a function of a dT parameter which is the difference
> between condenser entering and chilled water leaving temperatures. Its an
> attempt to account for chiller lift, but it does not give an efficiency
> credit for increasing the chilled water delta-T. So, you will not see the
> chiller efficiency boost in DOE2 for CAV systems due to a greater chilled
> water delta-T.
>
>
>
> In my experience, the VAV fan savings (and reduced chilled water load
> savings) usually outweigh the pump and chiller savings for CAV. However,
> it varies from building to building. For example, if you had a rare
> building with a low air-side static pressure drop to begin with and a long,
> high head pumping system, then its possible that the CAV system will be more
> efficient overall.
>
>
>
> Aaron
>
> On Mon, Mar 21, 2011 at 8:13 AM, James V Dirkes II, PE <jvd2pe at tds.net>
> wrote:
>
> Deepak,
>
> Here are some thoughts:
>
> · Less fan energy = less cooling load, since the fan energy is a
> part of the total cooling load.
>
> · If the pump is variable volume, the pump energy required for VAV
> fans will be slightly less due to less fan heat to cool.
>
> · If you are using the identical chiller for each system (VAV,
> CAV), then the chiller should use less energy also, due to less fan and pump
> heat.
>
> · A more common comparison would be to contrast a VAV chiller
> system with a CAV packaged rooftop system. For that comparison, the part
> load efficiencies of chiller and compressor / DX coil will be a major
> factor. Dehumidification will also be different for DX vs. chilled water
> coils.
>
>
>
> *The Building Performance Team
> James V. Dirkes II, P.E., LEED AP
> *1631 Acacia Drive NW
> Grand Rapids, MI 49504
> 616 450 8653
>
>
>
> *From:* bldg-sim-bounces at lists.onebuilding.org [mailto:
> bldg-sim-bounces at lists.onebuilding.org] *On Behalf Of *Deepak Tewari
> *Sent:* Monday, March 21, 2011 2:31 AM
> *To:* bldg-sim at lists.onebuilding.org
> *Subject:* [Bldg-sim] Difference in chiller energy for VAV and CAV system
>
>
>
> Dear All,
>
> I am comparing the energy performance of a constant volume and variable
> volume system for a composite climate of India (New Delhi) in EnergyPlus.
> The building area is 7500 sq m. The chiller capacity is same for both the
> cases. The chilled water to the cooling coils is supplied by a constant
> speed pump.
>
> The savings in the fan energy is evident due to variable speed of the
> supply fan in case of VAV. However i am getting energy saving in cooling
> energy (chiller energy) also, in VAV compared to CAV, which i feel is due to
> higher delta T (chilled water) across cooling coil for CAV compared to VAV,
> this in turns increases the chiller electricity consumption. However while
> discussions with some consultant, it is their feeling that the cooling
> energy would remain same for both type of systems.
>
> I want to ask has someone else tried this simulation and would there be any
> difference in cooling energy or not?
> Thanks in advance.
> Deepak
>
>
>
>
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>
>
>
> --
> Sent from my DynaTAC 8000x
>
>
>
>
>
>
> --
> Sent from my DynaTAC 8000x
>
>
> ---------- Forwarded message ----------
> From: "Nick Caton" <ncaton at smithboucher.com>
> To: "John T. Forester" <JohnTF at BVHis.com>, <
> equest-users at lists.onebuilding.org>
> Date: Thu, 4 Nov 2010 14:32:28 -0500
> Subject: Re: [Equest-users] Chiller Curves (oh boy!)
>
> Thanks to some extra guidance from John Forester and David Eldrige, I can
> tie up some loose ends Ieft on the list this week.
>
>
>
> Analyzing the isolated default curves plotted out, I failed to keep one
> thing in perspective: while each demonstrates how the variables (CHWT, CWT,
> dT, PLR) independently affect a chiller’s performance, the three curves
> ultimately work in concert to produce a net effect each hour.
>
>
>
> The EIR-FPLR&dT curve appeared wonky to me because I didn’t remember the
> normalized EIR is simulataneously affected by the CHWT and CWT values,
> independent of the dT.
>
>
>
> I expect many eyes are glazing over =). This is really hard to convey in
> text alone, so I brought along some show-and-tell pictures for the group:
>
>
>
> The following is the two default EIR curves: EIR-f(t1, t2) and EIR-f(PLR,
> dT) I showed earlier, multiplied together for a single CHWT and various
> CWT’s.
>
> In a nutshell, this illustrates how efficiency changes independent of the
> effects of the water temperatures on the chiller’s hourly capacity.
>
> The combined effects of the 2 curves moves their “sweet spots” into the
> range I was expecting:
>
> [image: cid:image002.png at 01CB7C15.4E6F3720]
>
>
>
> …And the following is the same thing, but adding the effects of the CAP-FT
> curve to the mix: all 3 default curves applied together in concert.
>
> This is what you’re modeling for a centrifugal VSD chiller every time you
> rely on the library default curves.
>
>
>
> Condenser water temps straying far from the rated conditions (85) get an
> efficiency penalty between these curves, just as the isolated CAP-FT curve
> indicated.
>
> These curves pass my personal gut check: they look very much like some
> chiller curves I’m used to seeing.
>
>
>
> Of note: This visual can serve as a great reference for judging whether
> developing custom curves is a worthwhile venture for a given chiller.
>
> [image: cid:image003.png at 01CB7C15.4E6F3720]
>
>
>
> In conclusion, the default curves for centrifugal VSD chillers aren’t that
> crazy after all, but be cautioned they can definitely be very different from
> your actually equipment.
>
>
>
> I tried briefly to figure out who the author(s) of that EDR guideline were
> 5 years ago, but came up empty handed…
>
> Does anyone else agree or disagree with me & John regarding whether it
> should be fundamentally sound to define curves from design capacities on
> downward (setting DESIGN-PLR=1.0), as long as those capacities aren’t
> exceeded in the model at-hand? I’d feel comfier if it felt like a consensus
> =).
>
>
>
> Thanks everyone,
>
>
>
> ~Nick
>
>
>
> [image: cid:489575314 at 22072009-0ABB]**
>
> * *
>
> *NICK CATON, E.I.T.***
>
> PROJECT ENGINEER
>
> 25501 west valley parkway
>
> olathe ks 66061
>
> direct 913 344.0036
>
> fax 913 345.0617
>
> *Check out our new web-site @ *www.smithboucher.com* *
>
>
>
> *From:* John T. Forester [mailto:JohnTF at BVHis.com]
> *Sent:* Wednesday, November 03, 2010 3:42 PM
> *To:* Nick Caton; equest-users at lists.onebuilding.org
> *Subject:* RE: [Equest-users] Chiller Curves (oh boy!)
>
>
>
> Nick,
>
>
>
> Thanks for adding your thoughts. I believe you and I are on the same page
> here.
>
>
>
> On item 2 below, the help files state that the EIR-FPLR&dT curve must be
> normalized to “full-load” or “maximum capacity” and not the design
> capacity. Intuitively (maybe), if you normalize these curves to the design
> capacity and then set the DESIGN-PLR to 1.0, it seems that this is locking
> in your design values as maximum values. Physically, the machine may have
> more capacity, but your energy model will be limited to these hard-coded
> design values.
>
>
>
> One way to check the model curve accuracy is to use hourly report
> blocks/reports to track the CHW supply temp, entering CW temp, chiller PLR,
> chiller EIR. Use your normalized curves to calculate the EIR for each hour
> with the CHW and CW temps and PLR. Then compare your calculated EIR with
> the EIR from eQuest. I believe you can also track the chiller capacity to
> see if it is holding the max capacity based on the DESIGN-PLR value and
> chiller capacity value you enter.
>
>
>
> John
>
>
>
> John T. Forester, P.E., LEED AP, Mechanical Design Engineer *I BVH
> Integrated Services I** *617.658.9008 tel *I** *617.244.3753 fax *I** *One
> Gateway Center Suite 506, Newton MA 02458 *I www.bvhis.com I Hartford ●
> New Haven ● Boston*
>
> <hr size=2 width="100%" align=center tabindex=-1>
>
> *From:* Nick Caton [mailto:ncaton at smithboucher.com]
> *Sent:* Wednesday, November 03, 2010 3:40 PM
> *To:* John T. Forester; equest-users at lists.onebuilding.org
> *Subject:* RE: [Equest-users] Chiller Curves (oh boy!)
>
>
>
> Yikes… looks like a slew of responses got out before I finished this one,
> but I have a lot to say =)… For context you might want to check which email
> I’m responding to first, everyone ;).
>
>
>
> John, thanks very much for the encouragement. I think I can help further
> your thoughts:
>
>
>
> 1. Getting a manufacturer vendor to cooperate is indeed tricky for
> all parties, and I’m not convinced their selection software really affords
> them the capability to find maximum loading points for varying
> condenser/evaporater temps in a time-efficient fashion… time will tell but
> I’ve got a very smart rep right now promising to see what he can do.
>
> 2. I’d rest easier knowing it’s perfectly fine to normalize all
> three curves to the design conditions and have a PLR of 1.0 equal the design
> conditions… except for the DOE2 help entries explicitly telling us that for
> centrifugal chillers, “full load” means “maximum” (see the highlighted
> copy-paste job way down below and the entry for EIR-FPLR as well).
>
>
>
> That said, your call to better understand the default curves sounds a lot
> like a request, so perhaps I can scratch your back in return ;). Here are
> the three curves eQuest pulls from its library when you specify a water
> cooled centrifugal chiller… visualized!
>
>
>
> Note that each curve is indeed normalized to (Z=1.0 at) ARI conditions.
> I’ve followed each with my (novice) observations/commentary.
>
> The EIR-FPLR&dT curve seems, well, kinda wacky to me! I’ve conferred with
> a few other mechanical designers, and we seem to agree that an efficiency
> “sweet spot” for a centrifugal variable speed chiller should lie somewhere
> between zero and full loading conditions – this curve’s shape seems to
> demonstrate continually improving efficiencies as you approach zero
> loading. Truthfully, there’s a very slight apex that’s hard to see (you can
> tell by the curving bands) just off the charted values shown between the 10%
> and 20% loading marks, but what chiller has an optimum efficiency at 15%
> loading? I’d of this as a “normal” shape if the z-axis were on some scale
> of straight power (kW)… I’d expect that to continually drop off with the PLR
> in this fashion, but that z-axis is normalized EIR (kW/ton conceptually, if
> not in magnitude)… shouldn’t the default curve have a “sweet-spot”
> efficiency somewhere in the vicinity of 40-60% loading?
>
> This EIR-FT curve is again normalized (1.0) at ARI conditions, and tells us
> that the chiller will be pretty much linearly more efficient as you increase
> the CHWT target temperature, and will exponentially increase in efficiency
> as the condenser water temperature drops. Raising either has less of an
> inverse effect. Nothing seems odd to me.
>
> This curve is also normalized (1.0) at ARI conditions, and is telling us
> the chiller loses capacity when the condenser water either rises or falls
> from ARI conditions (20-30% drop from ARI, when CWT is at 100F or 50F, for
> example). I’m too new at this to know whether that makes total sense, but
> my initial guess would be that colder condenser water would always be help
> improve capacity… I’d infer from this curve that centrifugal chillers are
> designed and optimized around a specific condenser water temperature, and
> that hotter *or* colder condenser water temperatures, for the same CHWT,
> hurts your equipment’s potential capacity. I suppose it might well be a
> function of the refrigerant’s thermodynamic properties? The CHWT selected
> has a linear, but a relative to the CWT minor effect on the capacity of the
> chiller.
>
>
>
> 3. You’ve nailed my current approach on the head! I’m just
> concerned that going against the explicit instructions in the DOE2 help
> entries (mentioned above) may have some significant impact on what I’m
> modeling…
>
> 4. Fully agreeing. And kudos for condensing paragraphs of fretting
> into a single line answer =).
>
>
>
> Thanks again so much for everyone’s input so far. I’d be curious to hear
> any other thoughts or second-opinions we as a group may have regarding:
>
> A. Why does the default part load curve above seems such an odd shape
> (at least to my eyes) for a centrifugal VSD chiller? Are my chiller
> fundamentals off?
>
> B. To what end/purpose do the DOE2 help docs and the EDR guidelines
> emphasis normalizing the EIR-FPLR curve to maximum vs. design capacities at
> the rated conditions, when you can normalize and specify to ARI conditions
> and set DESIGN-PLR=1.0 as John and I are discussing? I mean, I understand
> that you could get a “comprehensive” set of curves allowing you to apply the
> same chiller to other projects where you have a higher design capacity (or
> expect higher capacities will be required), but is there any inherent loss
> of accuracy if you build everything around data points encompassing all
> extremes present in the simulated model?
>
>
>
> ~Nick
>
>
>
> [image: cid:489575314 at 22072009-0ABB]**
>
> * *
>
> *NICK CATON, E.I.T.***
>
> PROJECT ENGINEER
>
> 25501 west valley parkway
>
> olathe ks 66061
>
> direct 913 344.0036
>
> fax 913 345.0617
>
> *Check out our new web-site @ *www.smithboucher.com* *
>
>
>
> *From:* John T. Forester [mailto:JohnTF at BVHis.com]
> *Sent:* Wednesday, November 03, 2010 11:49 AM
> *To:* Nick Caton; equest-users at lists.onebuilding.org
> *Subject:* RE: [Equest-users] Chiller Curves (oh boy!)
>
>
>
> Nick,
>
>
>
> I think you’re on the right track. Below are some of my thoughts on your
> conclusions. I hope the modeling community will set me straight if I’m
> wrong here.
>
>
>
> 1. Getting multiple performance runs from vendors that show part-load
> performance independent of the CW and CHW temps can often be challenging.
> Adding the “maximum capability” task to that for each of the conditions
> requires a pretty detailed understanding of the selection software. I’d say
> if you can get PLR data for 3-4 different CHW temps while holding the CW
> temps constant at 85, 75, 65 (and sometimes lower) – you’re ahead of most
> modelers. Working with the Mechanical Design Engineer and the vendor
> together has been successful for me in the past.
> 2. Defining the chiller capabilities at the “maximum” may only come
> into play if you expect your model to overload the chiller above the
> specified design capacity (I’m thinking building additions or process
> loads). At this point, this data (or knowing what the default eQuest curves
> do in that range) would be useful. Depending on your project, the time
> spent on developing curves for PLR >1.0 may not be justified.
> 3. If you don’t have “max” data and don’t want eQuest to assume
> performance at a part-load ratio >1.0, you can set the DESIGN-PLR to 1.0.
> 4. Either way, you want your curves to be normalized at whatever
> condition you specify (Design or Rated) and you want to enter those values
> on the Basic Specifications tab.
>
>
>
> John
>
>
>
> John T. Forester, P.E., LEED AP, Mechanical Design Engineer *I BVH
> Integrated Services I** *617.658.9008 tel *I** *617.244.3753 fax *I** *One
> Gateway Center Suite 506, Newton MA 02458 *I www.bvhis.com I Hartford ●
> New Haven ● Boston*
>
> <hr size=2 width="100%" align=center tabindex=-1>
>
> *From:* Nick Caton [mailto:ncaton at smithboucher.com]
> *Sent:* Wednesday, November 03, 2010 12:06 PM
> *To:* John T. Forester; equest-users at lists.onebuilding.org
> *Subject:* RE: [Equest-users] Chiller Curves (oh boy!)
>
>
>
> John,
>
>
>
> The design/max ratio is exactly what I’m discussing below when I say
> “DESIGN-PLR ratio,” so we’re definitely in the same ballpark =).
>
>
>
> I’d like to apply/paraphrase your advice to a few conditions to be sure I’m
> getting it correctly:
>
> - If we create all 3 custom curves, and normalize each to a point
> at maximum (not design) capacity, then the design-to-max ratio (DESIGN-PLR)
> should be set to 1.00.
>
> - If we create *only* the part load efficiency curve (EIR-FPLR or
> EIR-FPLR&dT), and wish to use the library defaults for EIR-FT and CAP-FT,
> then we should normalize this curve’s data points to ARI conditions (as
> that’s what the library curves are normalized to, per James’s email – I
> think I’ve read this somewhere also), specify an ARI capacity, EIR and
> conditions on the basic specifications tab, and enter a DESIGN-PLR of [ARI
> capacity/maximum capacity (for the same conditions)].
>
> - If we create all 3 custom curves, and try to normalize each to
> either ARI or design conditions, then we should specify capacity, EIR, CHWT,
> CWT and condenser GPM corresponding to either the ARI or design conditions
> of that normalizing point. In that case, we also specify a DESIGN-PLR using
> either the ARI or design capacity divided by the maximum capacity for the
> same conditions.
>
>
>
> *Profound (to me) Conclusion*: In *No* instance should we *Ever* attempt
> creating custom curves and NOT have at least one run from our manufacturer
> telling us what the maximum (not design) capacity is for the normalizing
> point. This conclusion would only apply to centrifugal chillers only.
>
>
>
> Does this all sound right?
>
>
>
> ~Nick
>
>
>
>
>
> James,
>
>
>
> Yeah, if all the part load data you received held the same CHWT and CWT
> equal, you might be able to make your part-load curve if it could have been
> a quadratic EIR-FPLR curve (like a reciprocating chiller), but not a
> bi-quadratic EIR-FPLR&dT (as with my centrifugal VSD chiller). You
> definitely could not approach generating custom EIR-FT or CAP-FT curves
> without varying condenser and chilled water temps. That exact issue
> happened to me the first few times I tried to reign my chiller reps in =).
>
>
>
> This time, I convinced my rep to give me multiple part load runs holding
> the CHWT constant and varying the CWT incrementally. This let me build the
> bi-quadratic EIR-FPLR&dT curve as I had at least three different dT’s
> represented in my part load data points. I plotted the 3D curve in excel to
> check my work and darned if the generated coefficients seem to be really
> accurate =)! It’s currently looking like a bittersweet revelation however
> – the library curve for a water-cooled centrifugal VSD chiller (see attached
> visualization) seems a LOT more generous (more efficient) at low part loads
> than the one I’ve generated which matches my rep’s data… I might share a
> visual of my custom curve for comparison once I’m dead-sure it’s accurate –
> I’m trying to clarify a few things with my rep right now.
>
>
>
> ~Nick
>
>
>
> [image: cid:489575314 at 22072009-0ABB]**
>
> * *
>
> *NICK CATON, E.I.T.***
>
> PROJECT ENGINEER
>
> 25501 west valley parkway
>
> olathe ks 66061
>
> direct 913 344.0036
>
> fax 913 345.0617
>
> *Check out our new web-site @ *www.smithboucher.com* *
>
>
>
> *From:* John T. Forester [mailto:JohnTF at BVHis.com]
> *Sent:* Wednesday, November 03, 2010 10:29 AM
> *To:* Nick Caton; equest-users at lists.onebuilding.org
> *Subject:* RE: [Equest-users] Chiller Curves (oh boy!)
>
>
>
> Nick,
>
>
>
> When defining a centrifugal chiller in eQuest, one of the items on the
> Basic Specifications tab under the Design vs. Rated Conditions is a
> Design/Max Cap ratio. By default, this is 92% for a water cooled unit. I
> believe this gets at the discussion in the help pages that talks about
> maximum capacity versus design capacity and how the chiller vendor will spec
> a piece of equipment. Typically, vendors don’t often get asked (or provide)
> what the “Maximum” capacity of a spec’d unit is. Therefore the performance
> data that they provide are at “design conditions.”
>
>
>
> If you change the chiller type to a reciprocating chiller, this “Design/Max
> Cap” ratio is disabled and the default specified condition changes from
> “Design Conditions” to “Rated Conditions.” This suggests that there is
> little “extra” capacity when a selection is done for that type of chiller.
>
>
>
> If you do get “maximum capacity” data and create curves from that data, you
> will want to change the Design/Max Cap ratio to 1.0 so eQuest knows that
> there isn’t any spare capacity at the chiller. Also if the data points you
> are using to normalize your curves are different than the design conditions
> for your energy model, you will want to change the “Chiller Specified at”
> value to “Rated Conditions” and enter the rated conditions for CHW temp, CW
> temp and CW gpm/ton to match your normalized curves.
>
>
>
> Hope this helps,
>
>
>
> John
>
>
>
> John T. Forester, P.E., LEED AP, Mechanical Design Engineer *I BVH
> Integrated Services I** *617.658.9008 tel *I** *617.244.3753 fax *I** *One
> Gateway Center Suite 506, Newton MA 02458 *I www.bvhis.com I Hartford ●
> New Haven ● Boston*
>
> <hr size=2 width="100%" align=center tabindex=-1>
>
> *From:* equest-users-bounces at lists.onebuilding.org [mailto:
> equest-users-bounces at lists.onebuilding.org] *On Behalf Of *Nick Caton
> *Sent:* Wednesday, November 03, 2010 11:03 AM
> *To:* Carol Gardner; equest-users at lists.onebuilding.org
> *Subject:* Re: [Equest-users] Chiller Curves (oh boy!)
>
>
>
> Thanks for the response Carol!
>
>
>
> That 120% load case is what I’m getting at – let me try to explain a little
> further:
>
>
>
> In the DOE2 help files, the vocabulary for centrifugal chillers is “design
> capacity” and “maximum capacity,” where “design” means the capacity at the
> rated or designed conditions (at which you define / specify your chiller),
> and “maximum” means the capacity the chiller is really capable of under the
> same conditions if it runs balls-out (maximum power to the refrigerant
> drive).
>
>
>
> The help file excerpt I copied below with the red line is pretty explicitly
> telling us to normalize the part load values to the *maximum* capacity for
> centrifugal chillers. I’ve highlighted a second line for clarity. The EDR
> guidelines I linked below are saying you can instead normalize to the *
> design* capacity for the EIR-PLR curve if that’s all your field
> measurements or manufacturer rep can provide.
>
>
>
> I’m asking – are both approaches right?
>
>
>
> My first and second questions are kinda tied together… How would choosing
> to normalize to either the maximum or design conditions affect how we should
> handle the DESIGN-PLR ratio, if at all?
>
>
>
>
>
> ~Nick.
>
>
>
> [image: cid:489575314 at 22072009-0ABB]**
>
> * *
>
> *NICK CATON, E.I.T.***
>
> PROJECT ENGINEER
>
> 25501 west valley parkway
>
> olathe ks 66061
>
> direct 913 344.0036
>
> fax 913 345.0617
>
> *Check out our new web-site @ *www.smithboucher.com* *
>
>
>
> *From:* Carol Gardner [mailto:cmg750 at gmail.com]
> *Sent:* Tuesday, November 02, 2010 10:04 PM
> *To:* Nick Caton
> *Cc:* equest-users at lists.onebuilding.org
> *Subject:* Re: [Equest-users] Chiller Curves (oh boy!)
>
>
>
> Let me take a crack at this. If by design capacity you mean the chiller
> running at 100% load, you would create the curve(s) by normalizing around
> your ARI design conditions i.e. the PLR curve would be 1.0 at this point,
> call it ARI Cap and the other points would be 90% Cap/ARI Cap, 80% Cap/ARI
> Cap, etc. The same would go for your temp curves. If, however, your chiller
> is operating at 120%, or some such other level, I would normalize the curve
> around the ARI design conditions of the chiller at 120%. I had to do this
> for a VRV hp that was selected at the 120% design condition.
>
> I find this from the DOE2 manual the most helpful:
>
>
>
> Volume 2: Dictionary <http://volume2dictionary.htm/> > HVAC Components<http://hvaccomponents.htm/>>
> CURVE-FIT <http://curvefit.htm/> > INPUT-TYPE = DATA<http://inputtypedata.htm/>
> INDEPENDENT-2
>
> Used for all curves having two independent variables. A list of up to
> twenty values of the second independent variable. The number of values
> should be the same as for DEPENDENT.
>
> *Example 1*: defining a curve by inputting a set of data points.
>
> A packaged system (PZS) has cooling performance significantly different
> from that used in the default model. The manufacturer lists the data shown
> in Table 46, for cooling capacity, at 2000 cfm design air flow rate, as a
> function of outside dry-bulb temperature and entering wet-bulb temperature.
>
> Table 46 Cooling capacity (kBtu/hr) vs. temperature
>
> *Outside
> Dry-bulb*
>
> *Entering Wet-bulb*
>
> *72F*
>
> *67F*
>
> *62F*
>
> 85F
>
> 69
>
> 65
>
> 60
>
> 95F
>
> 68
>
> 63 (ARI)
>
> 57
>
> 105F
>
> 65
>
> 60
>
> 53
>
> 115F
>
> 62
>
> 55
>
> 49
>
>
>
> In this example the independent variables are the entering wet-bulb
> temperature and the outside dry-bulb temperature. Because there are two
> independent variables and they have units of temperature, we input a curveof TYPE BI-QUADRATIC-T using the given data points. The dependent variable
> is not the cooling capacity listed in the table but rather the cooling
> capacity divided by the cooling capacity at the ARI rating point (95 F
> outside dry-bulb and 67 F entering wet-bulb). In other words, the capacities
> should be normalized to the ARI rating point., as shown in Table 47
>
> Table 47 Normalized capacity vs. temperature
>
> *Outside
> Dry-bulb*
>
> *Entering Wet-bulb*
>
> *72F*
>
> *67F*
>
> *62F*
>
> 85F
>
> 1.095
>
> 1.032
>
> 0.952
>
> 95F
>
> 1.079
>
> 1.0 (ARI)
>
> 0.905
>
> 105F
>
> 1.032
>
> 0.952
>
> 0.841
>
> 115F
>
> 0.984
>
> 0.873
>
> 0.778
>
>
>
> The CURVE-FIT input will look like the following:
>
> CAP-CURVE-1 = CURVE-FIT
> TYPE = BI-QUADRATIC-T
> INPUT-TYPE = DATA
> DEPENDENT = (1.000,1.079,0.905,1.032,0.952,0.841,
> 0.984,0.873,0.778,1.095,1.032,0.952) ..
> IN-TEMP1 = ( 67, 72, 62, 72, 67, 62,
> 72, 67, 62, 72, 67, 62) ..
> IN-TEMP2 = ( 95, 95, 95, 105, 105, 105,
> 115, 115, 115, 85 85, 85) ..
>
> *Example 2:* Defining a curve by inputting coefficients
>
> We want a furnace to have a constant efficiency as a function of part load.
> To do this we must replace the default FURNACE-HIR-FPLR with a curve that
> will give a constant efficiency. The curve TYPE is QUADRATIC in the part
> load ratio (PLR). PLR correction curves are always multiplied by the unit
> capacity, not the load, to obtain the energy (fuel or electricity) use. Thus
> the curve we want is: 0.0 + 1.0*PLR + 0.0*PLR*PLR. The input will look
> like:
>
> New-Furnace-HIR-fPLR = CURVE-FIT
> TYPE = QUADRATIC
> INPUT-TYPE = COEFFICIENTS
> COEFFICIENTS = (0.0,1.0,0.0) ..
>
> Then in the SYSTEM command we include:
>
> FURNACE-HIR-FPLR = New-Furnace-HIR-fPLR
>
>
>
> On Tue, Nov 2, 2010 at 3:21 PM, Nick Caton <ncaton at smithboucher.com>
> wrote:
>
> Hi everyone!
>
>
>
> I think I have *finally* wrapped my mind completely around custom chiller
> performance curves for a centrifugal VSD chiller. I’ve got a few specific
> questions now that I’m on the other side of the fence:
>
>
>
> 1. Is it necessary for the data points of a part load efficiency
> curve (EIR-FPLR&dT in my case) to originate from data with a 1.0 (100%) PLR
> ratio corresponding to a maximum vs. a design load capacity? From what I
> gather in the EDR reference<http://www.energydesignresources.com/Portals/0/documents/DesignGuidelines/EDR_DesignGuidelines_%20HVAC_Simulation.pdf>(re: “Method 2” on PDF page 32/65), this curve can be generated using
> part-load readings assuming a *design* capacity at the 100% loading mark…
> but the DOE2 help entry for “EIR-FPLR” seems to suggest otherwise (copied
> below – see highlighted line).
>
> 2. If the above part load efficiency curve is created based on data
> where the 100% loading point corresponds to the maximum (not design)
> capacity, should “DESIGN-PLR” (the ratio of design to maximum capacity) be
> set to 1.00 and the capacity of the chiller be specified at its maximum (not
> design) for the design/rated conditions? As I write this question it sounds
> like I’m chasing my tail – someone straighten me out =)!
>
> 3. When you veterans finish a project with sets of custom
> performance curves, do you have any suggestions for a naming scheme for
> future reference/re-use? I’m currently thinking to keep the curves grouped
> in an .inp snippet I for importing along with an equipment cutsheet… but I’m
> certain I’ll forget the all the details as quickly as humanly possible when
> this project is behind me…
>
>
>
> ~Nick
>
>
>
> [image: cid:489575314 at 22072009-0ABB]
>
> * *
>
> *NICK CATON, E.I.T.*
>
> PROJECT ENGINEER
>
> 25501 west valley parkway
>
> olathe ks 66061
>
> direct 913 344.0036
>
> fax 913 345.0617
>
> *Check out our new web-site @ *www.smithboucher.com* *
>
> *EIR-FPLR*
>
> Takes the U-name of a curve that adjusts the electric input ratio as a
> function of
>
> · *The part load ratio (PLR)* – The PLR is defined as the ratio of the
> hourly load to the hourly capacity; Load / Caphour
>
> · *The evaporator/condenser dT* - The temperature differential between
> the condenser and leaving chilled-water. The meaning of the condenser
> temperature varies according to condenser type.
>
> For most chillers, the dT has a relatively small effect on part-load
> performance. However, for variable-speed centrifugal chillers, the effect of
> dT is as important as the PLR. This is because the pressure rise across the
> impeller is proportional to the square of the impeller’s speed. Unless some
> form on condenser temperature relief is employed to reduce the temperature
> (and pressure) differential across the chiller at part load, the performance
> of a variable-speed chiller may not be significantly different than that of
> a constant-speed chiller.
>
> To model power consumption as a function of the PLR only, use a CURVE-FIT
> of TYPE = QUADRATIC or CUBIC. To model as a function of both PLR and dT,
> use a BI-QUADRATIC-RATIO&DT curve. *The curve must be normalized to 1.0 at
> full load and the rated temperature differential. *
>
> *Note that, for centrifugal chillers, ‘full load’ is defined as the
> ‘maximum capacity’, not the ‘design capacity’.* Refer to the DESIGN-PLR
> keyword for more information.
>
>
>
>
> _______________________________________________
> Equest-users mailing list
> http://lists.onebuilding.org/listinfo.cgi/equest-users-onebuilding.org
> To unsubscribe from this mailing list send a blank message to
> EQUEST-USERS-UNSUBSCRIBE at ONEBUILDING.ORG
>
>
>
>
> --
> Carol Gardner PE
>
> _______________________________________________
> Equest-users mailing list
> http://lists.onebuilding.org/listinfo.cgi/equest-users-onebuilding.org
> To unsubscribe from this mailing list send a blank message to
> EQUEST-USERS-UNSUBSCRIBE at ONEBUILDING.ORG
>
>
> ---------- Forwarded message ----------
> From: Pedro Peixeiro <ppeixeiro at lnec.pt>
> To: bldg-sim at lists.onebuilding.org
> Date: Wed, 23 Mar 2011 14:38:50 +0000
> Subject: Re: [Bldg-sim] Double Facades - EPlus
> Hi Francisco.
>
> If your facade is made up of only opaque construction and/or you want to
> make a simple study of it, you can check the
> SurfaceProperty:ExteriorNaturalVentedCavity. For more detailed modelling, or
> if you facade is made of glassings, you should model the facade as a
> independent zone, and use airflownetwork objects to setup openings, virtual
> partitions and airflow.
> Convection on the outside of the facade shouldn't be much of a problem, the
> tricky one is the inside convection. EPlus doens't have an algorithm
> specified for these kinds of building elements, so you'll have to choose the
> one that best suits your needs.
>
> Pedro.
>
>
>
> On 22-03-2011 18:44, Francisco Massucci wrote:
>
> Hi,
>
> Does anyone knows how to modeling double facedes in EnergyPlus? Like a
> lightweight ceramic facede, located 10cm away from a traditional concrete
> masonry wall. I figured if modeling an thin extra zone could be work, or if
> its possible to work with the second facede only as a huge shading device. I
> think the most important in these cases is the amount of natural
> convection that occur around the exterior of the building but none of my
> proposals, this fact is taken into account.
> I appreciate if anyone can help me,
> Sorry about my bad english.
>
> Francisco Massucci
> Architect - São Paulo - Brasil
>
>
> _______________________________________________
> Bldg-sim mailing listhttp://lists.onebuilding.org/listinfo.cgi/bldg-sim-onebuilding.org
> To unsubscribe from this mailing list send a blank message to BLDG-SIM-UNSUBSCRIBE at ONEBUILDING.ORG
>
>
>
>
> ---------- Forwarded message ----------
> From: Evgenia Gorbachinsky <gorbachinsky at gmail.com>
> To: bldg-sim at lists.onebuilding.org
> Date: Wed, 23 Mar 2011 13:51:36 -0400
> Subject: [Bldg-sim] Corporate Deduction, comparison of the proposed design
> with the baseline design by ASHRAE 90.1-2001
> Good Afternoon,
>
> Our client would like to get a tax deduction reducing the building's energy
> and power costs by 50% in comparison to a building meeting requirements set
> by ASHRAE Standard 90.1-2001. This standard does not have Appendix G.
> Could anybody help to understand,please, how I can do it.
> Do I need to Use section 11 ( Energy cost budget method) of the standard
> or I need to use the same systems and plants in both cases, but different
> lighting density, building envelope and energy rates according to the actual
> design for the proposed design and Standard 90.1-2001 for the baseline
> design?
>
>
> Thanks.
>
> --
> With best wishes,
> Genia Gorbachinsky
>
>
> ---------- Forwarded message ----------
> From: "Deru, Michael" <Michael.Deru at nrel.gov>
> To: Evgenia Gorbachinsky <gorbachinsky at gmail.com>, "
> bldg-sim at lists.onebuilding.org" <bldg-sim at lists.onebuilding.org>
> Date: Wed, 23 Mar 2011 12:04:52 -0600
> Subject: Re: [Bldg-sim] Corporate Deduction, comparison of the proposed
> design with the baseline design by ASHRAE 90.1-2001
>
> Dear Genia,
>
>
>
> Please see the DOE web site for more information about the tax deduction
> and the following NREL report for guidance on calculating the savings. In
> addition, DOE and NREL are working on a simplified tool for the tax
> deduction calculations that will be available in April.
>
>
>
> http://www1.eere.energy.gov/buildings/tax_incentives.html
>
> http://www.nrel.gov/docs/fy07osti/40467.pdf
>
>
>
> Michael
>
>
>
> Michael Deru, Ph.D.
>
> Senior Engineer II
>
> Commercial Buildings Research Group
>
> National Renewable Energy Laboratory
>
> 303-384-7503 (o)
>
> 303-725-3528 (c)
>
> *From:* bldg-sim-bounces at lists.onebuilding.org [mailto:
> bldg-sim-bounces at lists.onebuilding.org] *On Behalf Of *Evgenia
> Gorbachinsky
> *Sent:* Wednesday, March 23, 2011 11:52 AM
> *To:* bldg-sim at lists.onebuilding.org
> *Subject:* [Bldg-sim] Corporate Deduction, comparison of the proposed
> design with the baseline design by ASHRAE 90.1-2001
>
>
>
> Good Afternoon,
>
> Our client would like to get a tax deduction reducing the building's energy
> and power costs by 50% in comparison to a building meeting requirements set
> by ASHRAE Standard 90.1-2001. This standard does not have Appendix G.
> Could anybody help to understand,please, how I can do it.
> Do I need to Use section 11 ( Energy cost budget method) of the standard
> or I need to use the same systems and plants in both cases, but different
> lighting density, building envelope and energy rates according to the actual
> design for the proposed design and Standard 90.1-2001 for the baseline
> design?
>
>
> Thanks.
>
> --
> With best wishes,
> Genia Gorbachinsky
>
>
> ---------- Forwarded message ----------
> From: "Robert Gengelbach" <rgengelbach at sustainablemech.com>
> To: "'Evgenia Gorbachinsky'" <gorbachinsky at gmail.com>, <
> bldg-sim at lists.onebuilding.org>
> Date: Wed, 23 Mar 2011 14:05:04 -0400
> Subject: Re: [Bldg-sim] Corporate Deduction, comparison of the proposed
> design with the baseline design by ASHRAE 90.1-2001
>
> There are specific rules for the procedure included in the NREL/TP
> 550-40467. You are supposed to follow the 90.1-2004 Appendix G (since to
> 2001 does not have an Appendix G) you are also supposed to use many
> utilization and tstat schedules from California Title 24.
>
>
>
> *[image: cid:image003.png at 01C9AB43.F0BEE290]*
>
> *Robert Gengelbach, PE, BEMP, LEED*®* **AP BD+C*
>
> *Sustainable Mechanical Design Associates, Inc*
>
> 89 Monroe Center NW
>
> Suite 302
>
> Grand Rapids, MI 49503
>
> P: (616) 776-9009
>
> F: (616) 776-9010
>
> C: (616) 570-2329
>
> www.sustainablemech.com
>
> rgengelbach at sustainablemech.com
>
> * *
>
> P* **Please print only if necessary*
>
>
>
>
>
> *From:* bldg-sim-bounces at lists.onebuilding.org [mailto:
> bldg-sim-bounces at lists.onebuilding.org] *On Behalf Of *Evgenia
> Gorbachinsky
> *Sent:* Wednesday, March 23, 2011 1:52 PM
> *To:* bldg-sim at lists.onebuilding.org
> *Subject:* [Bldg-sim] Corporate Deduction, comparison of the proposed
> design with the baseline design by ASHRAE 90.1-2001
>
>
>
> Good Afternoon,
>
> Our client would like to get a tax deduction reducing the building's energy
> and power costs by 50% in comparison to a building meeting requirements set
> by ASHRAE Standard 90.1-2001. This standard does not have Appendix G.
> Could anybody help to understand,please, how I can do it.
> Do I need to Use section 11 ( Energy cost budget method) of the standard
> or I need to use the same systems and plants in both cases, but different
> lighting density, building envelope and energy rates according to the actual
> design for the proposed design and Standard 90.1-2001 for the baseline
> design?
>
>
> Thanks.
>
> --
> With best wishes,
> Genia Gorbachinsky
>
>
> ---------- Forwarded message ----------
> From: "Hensen, J.L.M." <j.hensen at tue.nl>
> To: "bldg-sim at lists.onebuilding.org" <bldg-sim at lists.onebuilding.org>, "
> ibpsausa at lists.onebuilding.org" <ibpsausa at lists.onebuilding.org>, "
> esp-r at lists.strath.ac.uk" <esp-r at lists.strath.ac.uk>
> Date: Wed, 23 Mar 2011 19:08:01 +0100
> Subject: [Bldg-sim] fully funded PhD position at TU Eindhoven
>
> Dear all,
>
> We currently have a fully funded building performance simulation PhD
> position available. The project is a part of the just started
> Dutch research project “Climate Proof Cities”
> http://knowledgeforclimate.climateresearchnetherlands.nl/nl/25222878-Climate_Proof_Cities.html which
> involves a large number of universities and research institutes. The aim of
> this programme is to generate knowledge for adapting the built environment
> in order to cope with future climate change.
>
> Details about the vacancy “Climate change adaptation measures: adaptive
> buildings and occupants” are at
> http://jobs.tue.nl/wd/plsql/wd_portal.show_job?p_web_site_id=3085&p_web_page_id=109720&p_order_by=
>
> Please don't hesitate to contact me for further information.
>
> I would appreciate it very much if you could forward this message
> to potential applicants.
>
> Thanks in advance!
> Jan
>
>
>
> ........................................
>
> prof. dr. ir. Jan L.M. Hensen | Eindhoven University of Technology | Building
> Physics & Systems | P.O. Box 513 - VRT6.18 | 5600 MB EINDHOVEN,
> Netherlands | +31 (0)40 247 2988 | www.bwk.tue.nl/bps/hensen
>
>
>
>
>
>
> ---------- Forwarded message ----------
> From: Kerry Gorczynski <kgorczynski at olace.com>
> To: "bldg-sim at lists.onebuilding.org" <bldg-sim at lists.onebuilding.org>
> Date: Wed, 23 Mar 2011 14:52:52 -0400
> Subject: [Bldg-sim] 90.1 Appendix G - Resizing Baseline Systems to Meet
> Unmet Load Requirements (G3.1.2.2)
>
> Hello Everyone,
>
>
>
> I know there have been quite a few posts in the past regarding the
> definition and clarification of unmet hours in an energy model. I had a
> question outside of that – particularly when the baseline system needs to be
> resized to meet the requirements of G3.1.2.2:
>
>
>
> If unmet load hours in the p*roposed design *exceed the unmet load hours
> in the *baseline building *by more than 50, simulated capacities in the *baseline
> building *shall be decreased incrementally and the building resimulated
> until the unmet load hours are within 50 of the unmet load hours of the *proposed
> design*.
>
>
>
> When we do this, do we need to resize the CFM of the system to maintain the
> supply-air-to-room-air temperature difference of 20°F, etc. used in sizing
> the baseline? I could see this becoming a lengthy process of reducing
> cooling capacity, then fan CFM, etc. and was just wondering if anyone had
> any thoughts on it.
>
>
>
> Thanks,
>
> Kerry
>
>
>
> _______________________________________________
> Bldg-sim mailing list
> Bldg-sim at lists.onebuilding.org
> http://lists.onebuilding.org/listinfo.cgi/bldg-sim-onebuilding.org
>
>
--
D.E.V.S.Kiran Kumar
Graduate Student
Building Technology & Construction Management Division
Indian Institute of Technology Madras
Mobile: +91 99622 47007
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