Let me walk through the sizing steps in the navigator before answer your specific questions as it will provide good background and be useful to other forum participants:
In the “HVAC Systems” second of the navigator, you create ApHVAC systems for your Baseline & Proposed buildings. When you click on the “System Parameters” link, the spreadsheets for the systems you created are generated. At this time, the Baseline HVAC file is copied for each of the 3 rotations and the corresponding spreadsheets are created as well. At this stage, the spreadsheets are not populated.
Further down the navigator, you “Generate the baseline model”. This step creates the Baseline building by applying the PRM rules to your Proposed building.
Once the Baseline building is generated, you move on to the sizing runs. First up is “Room Load Calculations”. This sizing step determines the load in each room for the Proposed building, Baseline building, and Baseline building rotations (assuming you check the boxes to perform them all). Room loads are calculated using the ASHRAE Heat Balance Method and the results of those calculations populate the spreadsheets created above.
The “Access Loads Data Spreadsheets” link in the navigator connects you to the folder on your computer where the spreadsheets are saved. You can open them up to make changes as needed. You may not need to make any changes, depending on your building, design stage, etc, but a review of the data here, including the 62.1 OA Calculations, is encouraged.
Once your spreadsheet changes (if any) are finalized, you’re ready to “Assign Room Sizing Data”. This step copies data from the spreadsheets into the corresponding ApHVAC networks. This copy/paste communication only flows one direction and only happens when you perform this step. That is, if you make changes to the ApHVAC network, they do not write backwards to the spreadsheet. If you make changes the ApHVAC network, then perform this step again, the spreadsheet may overwrite those changes. If you make changes to the spreadsheet and don’t perform this step, the changes are never made in the ApHVAC network.
“System Load Calculations” looks at the information in your ApHVAC files and sizes the equipment and plant accordingly.
All of the above steps are the same in the navigator as within ApHVAC. The only reason you need to use the navigator (outside of preference/convenience) is to access the Baseline building. If you open the Baseline HVAC file in ApHVAC and perform the sizing steps there, the file will size using the Proposed building. To size the Baseline HVAC file to the Baseline building, you must perform the sizing in the navigator.
Answering your questions more specifically:
1) No, you do not have to size the Proposed building HVAC file to size the Baseline building HVAC file. Simply uncheck the “Proposed” option when prompted and only the Baseline & rotations will run.
If you are not sizing the Proposed, no changes will be made to your Proposed file. You can certainly do a “Save As” on your Proposed HVAC file and give it a new name as a backup, just in case you accidentally forget to uncheck the box.
What reports are you looking at that you see no Baseline data? What changes are you expecting to see in the HVAC Component results in VistaPro that are not appearing?
2) If there is an error in your ApHVAC file, you should see that error whether you perform the System Sizing in the navigator or within ApHVAC. It is possible you are sizing the Baseline HVAC file directly in ApHVAC? This would be the only instance where the two processes would differ (see above explanation). If you are not, I encourage you to send this model to
support@iesve.com so they can investigate.
What errors are you receiving? Are the specific to the network (negative flow, flow overspecified, mismatched control variable, etc) or something else related to sizing?
3) Looking at page 70 of the IES VE PRM Navigator User Guide, I see a System Sizing report for a System type 7. A system 7 is a VAV AHU with terminal units. At the top, I can see the coil sizes for the AHU cooling & heating coils. At the bottom, I see a list of “Rooms Served by System”. In this table there is only heating coil data and no cooling coil data, as I would expect. At the room level, there are only terminal units with reheat. The terminal units do not have cooling coils, thus there is no data here. All of the cooling is addressed the AHU level.
Thanks,
Megan
My apologies.