I am new to eQUEST and trying to model a VRF system. There is no such
option, so I think some people model it as PVVT. Any suggestions or
resources on that? Thank you very much.
Hi Eleni,
There are a resource that has been put together by modelers at the Energy Trust of Oregon on a work-around for VRF systems in eQUEST, see attached. Yes, the method is to use PVVT system types. If heat recovery is available there is a post-processing step with the hourly data to identify when simultaneous loads occur.
I am in a similar situation and wanted to contribute to the discussion.
Of the two approaches proposed by the BSUG (wshp vs. air cooled), which is the most accurate? Which is more conservative? Does one seem to be preferred over the other?
I like the WSHP approach because the way the systems are separated seems most like the way a vrv is actually assembled. The condenser water loop represents the exchange between the rooftop condenser and the refrigerant branch selector. The pvvt systems represent the fan coils for each zone. At least, I think I'm understanding this correctly. I like that I am able to put group the fan coil units as if they are connected to the same condenser, but I don't really know that much and wonder if this really matters as far as a simulation is concerned.
Have you considered bundling the zones into one DX zone combining the
loads and then using the AHRI SEER and EER for the entire bundle? That
seems pretty simple to me.
Just found this doc on VRF applications in the DOE2.1 engine. Haven't had a chance to dig through it but maybe some interesting information for the list.
Following the equations in the EnergySoft VRF Application it is possible to
do spreadsheet calculations that match EnergyPro's results very closely.
In our experience, at least in applications with limited heat recovery
opportunity, the air-cooled PVVT system matches the results of the VRF
equations quite closely without any additional calculations. The ECM to
apply the Energy Soft VRF equations usually only shows an additional
savings of 0.4% total building energy use.
This all assumes that EnergySoft's equations are correct. I haven't seen
any data that shows that these equations have been calibrated to actual VRF
energy use.
Try this...
Hi,
Check with this.
Thanks!
Hi Eleni,
There are a resource that has been put together by modelers at the Energy Trust of Oregon on a work-around for VRF systems in eQUEST, see attached. Yes, the method is to use PVVT system types. If heat recovery is available there is a post-processing step with the hourly data to identify when simultaneous loads occur.
Alea German
I am in a similar situation and wanted to contribute to the discussion.
Of the two approaches proposed by the BSUG (wshp vs. air cooled), which is the most accurate? Which is more conservative? Does one seem to be preferred over the other?
I like the WSHP approach because the way the systems are separated seems most like the way a vrv is actually assembled. The condenser water loop represents the exchange between the rooftop condenser and the refrigerant branch selector. The pvvt systems represent the fan coils for each zone. At least, I think I'm understanding this correctly. I like that I am able to put group the fan coil units as if they are connected to the same condenser, but I don't really know that much and wonder if this really matters as far as a simulation is concerned.
Regards,
Matt Clough
Have you considered bundling the zones into one DX zone combining the
loads and then using the AHRI SEER and EER for the entire bundle? That
seems pretty simple to me.
Robert Wichert P.Eng. LEED AP BD&C
Just found this doc on VRF applications in the DOE2.1 engine. Haven't had a chance to dig through it but maybe some interesting information for the list.
http://www.energysoft.com/ep/VRF%20Application.pdf
Timothy Howe, MS, LEED? AP BD+C
Following the equations in the EnergySoft VRF Application it is possible to
do spreadsheet calculations that match EnergyPro's results very closely.
In our experience, at least in applications with limited heat recovery
opportunity, the air-cooled PVVT system matches the results of the VRF
equations quite closely without any additional calculations. The ECM to
apply the Energy Soft VRF equations usually only shows an additional
savings of 0.4% total building energy use.
This all assumes that EnergySoft's equations are correct. I haven't seen
any data that shows that these equations have been calibrated to actual VRF
energy use.
Robby Oylear, PE, LEED AP