[Equest-users] [Bldg-sim] VRF performance curve

Thu May 28 05:10:39 PDT 2015

Dear All,
Thanks a lot for all the responses. I followed the procedure outlined in the LG guide. The overall savings are up by 13%, savings on cooling alone is up by 35% when compared to the default DX curves. Of course there is unmet hour issue as i have considered PSZ system.
Also i tried a few trials to understand which particular curve is responsible for the higher savings and found that "f(t entering wet bulb, t enter condenser) curve gives higher savings. And then changing the cooling capacity curve provides additional savings. The least impact is from the PLR curve.
Now the question is whether the savings achieved is justifiable. Has anyone else come across the same issue?.
I am concerned about the savings because, in a core and shell project, with DX curves the project is achieving 5% savings and once i input the VRF curves, the savings shoots to more than 15%. Meeting LEED mandatory is dependent on the VRF curves. 
I am working on Equest software. 
Regards,Rathnashree

  On Thursday, 28 May 2015 4:57 PM, Chris Yates <chris.malcolm.yates at gmail.com> wrote:

 Interesting post and thanks for the info - I find VRF a bit of a 'black box' when it comes to modelling. Part of the issue is the huge variety of indoor/ outdoor unit combinations.
I have no doubt that the better VRF systems are a superb technology. However, I do believe some of the performance claims are audacious (I can only speak of the European market). For example, heat recovery VRF with seasonal average heating COP (kW/kW)  > 8.0 and seasonal Cooling EER > 6 is competing with centrifugal chillers - the most advanced VRF compressor technology I know of is scroll.
I guess part of my beef is not trusting the Euro test standards for VRF!
Bye for now
Chris
On Wed, May 27, 2015 at 3:18 PM, Qureshi, Harris <Harris.Qureshi at stantec.com> wrote:

Hi Rathna, What software are you using ? You might want to go through the attached modelling protocol attached from LG as Sherif mentions .  Harris  Harris Qureshi, B.E(Mech), MSc. Energy, LEED AP HomesMechanical Engineer
Stantec
Dubai Investment Park, PO Box 52764 Dubai UAE 
Phone: +971-4-812-5947
Cell: +971-50-189-9924
Harris.Qureshi at stantec.com 
|  |

  The content of this email is the confidential property of Stantec and should not be copied, modified, retransmitted, or used for any purpose except with Stantec's written authorization. If you are not the intended recipient, please delete all copies and notify us immediately. ü Please consider the environment before printing this email. From: Bldg-sim [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Sherif Farag
Sent: Wednesday, May 27, 2015 5:26 PM
To: Rathna Shree
Cc: BldgSim Mailing List; equest-users at onebuilding.org
Subject: Re: [Bldg-sim] VRF performance curve Hi Rathna,LG has a plug-in that works good with eQuest, I tried it and I noticed the % of energy saving will be on the region of 20% when compared to PTAC (Not compared to the App G. Baseline).Thanks;Sherif FaragTechnical DirectorIntegrated Environmental Services (IES) Ltd. Abu Dhabi - UAE 
On May 27, 2015, at 11:18 AM, Rathna Shree <rathnashreep at yahoo.in> wrote: Dear All, I worked on a couple of projects in equest  using the VRF performance curves from Daikin and LG. The methodology i followed is as below: 1) Modelled packaged VAV with minimum flow ratio 1. 2) Created systems based on number of ODU's and assigned multiple zones to the respective ODU. (Just like modelling a AHU)3) Inputted the ODU Cooling capacity and supply flow4) Fans will be constant volume.5) Since it is a cooling only system, i assigned only the "Cool EIR - fEWB-OAT", "Cool-EIR-fPLR" and "Cool cap-fEWB&OAT" curves. Rest were all default DX unit curves.  PVAV system is used as PSZ system cannot handle multiple zones well thus causing unmet hours. I did 2 trials, one with default DX curves and the other with performance curves from LG and Daikin. The results showed a decrease in cooling energy consumption by more than 30% thus impacting the overall energy consumption by more than 10%.  Is the simulation methodology and results appropriate? I feel the savings is on a higher side. Please advise. Regards,Rathnashree_______________________________________________
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