[Bldg-sim] VRF performance curve

Tue Sep 1 06:53:18 PDT 2015

Hello Chris,

In regards to your VRF posting. We are currently finishing some work for the U.S. Army to verify the performance of a side-by-side test of a VRF system, which we have accomplished with a calibrated simulation. The results show a 35 to 50% savings when compared to the baseline air-cooled HVAC in the 1/2 of the building that was not retrofitted. The biggest factor in the savings is the individual zoning and the combination of zoning with motion sensors at each thermostat, which creates a building that has partial conditioning and different thermostat schedules for each zone, not simple to simulate. These results are based on measured data taken over the last 18 months.

Jeff

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________________________________
From: Bldg-sim [bldg-sim-bounces at lists.onebuilding.org] on behalf of Chris Yates [chris.malcolm.yates at gmail.com]
Sent: Thursday, May 28, 2015 6:27 AM
To: Qureshi, Harris; BldgSim Mailing List
Subject: Re: [Bldg-sim] VRF performance curve

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<mailto: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 Homes
Mechanical Engineer
Stantec
Dubai Investment Park, PO Box 52764 Dubai UAE
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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<mailto: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 Farag
Technical Director
Integrated Environmental Services (IES) Ltd.
Abu Dhabi - UAE

On May 27, 2015, at 11:18 AM, Rathna Shree <rathnashreep at yahoo.in<mailto: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 flow
4) 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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