[Bldg-sim] M&V metering of VRF systems

Aaron Smith asmith at mreng.ca
Fri May 23 05:08:18 PDT 2014


Chris,

I've talked to my local Mitsubishi rep in the past about installing VRF ‎systems in a condo building. Apparently they offer a package that monitors the expansion valve positions of the indoor units along with the branch box modes and energy use of the outdoor unit so that it can assign an energy use to each condo for billing purposes.   It probably isn't up to measurement canada specifications but may be fine for M&V.

I'd be interested in how your system performance plays out. You may be aware of the reports of the GSHP out-performing VRF (VRF uses much more than expected)  at ASHRAE headquarters. I haven't done M&V on a VRF system but the building energy use for a couple of our (air and water cooled) projects is much higher than expected.  

Something that we've noticed ‎on a recent air-cooled project that we're modeling with HAP is that it shows a significant penalty for systems that have a vertical height difference - it says the 1st floor would use 33% more heating energy than the 10th floor with roof mounted outdoor units. I realize there is a capacity reduction (which varies by manufacturer) but there must also be a corresponding increase in compressor electricity use. Or at least that's what I gather from the results.  I'll need to request their algorithms. 

Hope that helps,
Aaron

Aaron Smith, P.Eng
M&R Engineering Ltd.

Sent from my BlackBerry 10 smartphone on the TELUS network.
  Original Message  
From: Jones, Christopher
Sent: Thursday, May 22, 2014 14:02
To: bldg
Subject: [Bldg-sim] M&V metering of VRF systems

I am developing an M&V plan for a building with a VRF system. I am wondering if it is possible to meter the heating, cooling and fan energy of the VRF units given that the unit power is provided by a single feed. 

It seems like a complex task to accurately measure the heating and cooling energy given that the system includes the VRF cassettes, water cooled condenser, the fluid cooler, the branch controllers, and the boiler.

Thanks for any insights!

Christopher Jones, P.Eng. 
Tel: 416.644.4226 • Toll Free: 1.888.425.7255 x 527


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