[Bldg-sim] VRV System Equipment Efficiency

Mon Mar 15 07:11:05 PDT 2010

Gavin is correct that modeling VRV systems as heat pumps will not
demonstrate efficiencies related to part load operation.  Additionally,
efficiencies related to heat reclaim during periods of the year when
applicable will not be captured in the model.  Energy Pro, by
Energysoft, is the only software I am aware of that has the appropriate
algorithms programmed to provide accurate simulations.  Energy Pro is a
front end software package for DOE-2 simulation.  We have used it on
several occasions to demonstrate anticipated energy savings.

TIM REYNOLDS, P.E., LEED AP

Associate Principal

CB Engineers

600 108th Ave NE Suite 600 | Bellevue, WA 98004

T  425 564 8400 Ext 8431 | C 206 422 2547 | F 425 564 8517

tim.reynolds at cbengineers.com <mailto:tim.reynolds at cbengineers.com>  |
cbengineers.com <http://www.cbengineers.com/> 

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From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Gavin Gui
Sent: Monday, March 15, 2010 6:54 AM
To: Larry Degelman; Shubhra Kothari; reniel barroso
Cc: bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] VRV System Equipment Efficiency

I agree with Larry. There is no exact system specified in the ASHRAE
90.1 that matches the VRV system. We used to model the VRV system using
the efficiencies in Table 6.8.1B, however note that these efficiencies
are typically for full load operations, hence it will not capture the
advantage of the part load capability of the VRV systems. I.e. to say,
the savings calculated as such will be typically conservative.

Also note that VRV systems are generally waived from the DOE test
procedure applicable to commercial package air-cooled central air
conditioners and heat pumps (2 systems that I know of are the Mitsubishi
City-Multi and Sanyo VRV-III systems) although they have to comply with
the alternate testing procedure. So just take note of the system
efficiencies used for the modeling.

-------------------------------------------------

Gavin Gui

Project Engineer

ERS, Inc.

120 Water Street, Ste. 350

North Andover, MA 01845

Ph: 978-521-2550, x 236

Fax: 978-521-4588

ggui at ers-inc.com <mailto:jrogers at ers-inc.com>  

www.ers-inc.com <http://www.ers-inc.com/>  

-------------------------------------------------

From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Larry
Degelman
Sent: Monday, March 15, 2010 9:24 AM
To: Shubhra Kothari; reniel barroso
Cc: bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] VRV System Equipment Efficiency

Here's another opinion (non-authoritative): I believe the VRV efficiency
requirements would match best with the "air cooled, cooling and heating
modes" requirements in Table 6.8.1B (for heat pumps).  In the ECB
method, this would most likely be system 8, Packaged terminal heat
pumps.  I agree that the ventilation should be modeled separately as a
DOAS.

LOD

===========================
Larry O. Degelman, P.E.
Professor Emeritus of Architecture
Texas A&M University
===========================

From: Shubhra Kothari <mailto:shubhrakothari at gmail.com>  

Sent: Monday, March 15, 2010 12:32 AM

To: reniel barroso <mailto:renielbarroso at yahoo.com>  

Cc: bldg-sim at lists.onebuilding.org 

Subject: Re: [Bldg-sim] VRV System Equipment Efficiency

Well, there seems to be no ARI standard for testing VRV yet. So, you
won't find it in 90.1.  

The closest you can get is packaged single zone (match cooling capacity)
i believe but you'll have to figure out a way of modelling the fresh air
side- as DOAS or others. 

Thanks
Shubhra Kothari

On Mon, Mar 15, 2010 at 12:26 AM, reniel barroso
<renielbarroso at yahoo.com> wrote:

Hi to all!

Where can we find the Minimum Requirement System Efficiency of a VRV
System in ASHRAE 90.1?

Which of those systems mentioned in the ASHRAE 90.1 can we use to
compare such equipment?

Thanks

Reniel

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