[Equest-users] eQUEST 3.65 build 7175 VRF heating COP input

[Riley, Evan P]

Hey Danny,

This is interesting and I'd love to try and apply this some time. I'm having trouble deciphering the purpose of, and source of numbers for, each of the three tables. A little more explanation around each would be really helpful I think. Also, some definitions, such as the meaning of "SST" and "SDT." I haven't tried modeling VRFs in eQUEST in quite a few years, so while I'm sure I could dig into the eQUEST documentation to figure all that out, maybe a bit more description within your workbook would make that easier.

Thanks again for sharing this.

Evan Riley PE, BEMP, LEED AP BD&C
Sr. Energy Engineer, Building Sciences Studio | Mason & Hanger
O 804.822.3008 


-----Original Message-----
From: Danny Xu <dannyxu576 at gmail.com> 
Sent: Friday, August 22, 2025 10:41 AM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] eQUEST 3.65 build 7175 VRF heating COP input

Hello,

I’m currently modeling a VRF system in eQUEST 7175. The equipment cut sheets include both cooling EER and heating COP values. However, I noticed that the VRF condensing unit input in eQUEST only allows for cooling efficiency—there’s no direct field for heating COP.

I looked into this and wasn’t able to find any documentation or settings that allow for a direct input of heating COP.

Here’s the approach I’ve taken to work around this:

For compressor energy consumption in cooling, heating, or combined modes, I’m using the following formula:

P = Prated × EIR_FPLR × EIR_FT × CAP_FT

The default performance curves applied are:

VRF044-Cap-fSST&SDT

VRF044-EIR-fSST&SDT

VRF044-EIR-fPLR

Energy consumption is calculated as follows:

At cooling SST & SDT → based on cooling EER

At heating SST & SDT → based on heating COP

So, instead of directly inputting both cooling and heating EIR values, I rely on:

Cooling EIR

Cooling SST & SDT (used to calibrate the default curve)

Heating SST & SDT (used to reflect heating performance through the same default curve)

A detailed breakdown of the calculations is provided in the attached Excel file.