SEER and HSPF in E+/Design Builder
Has anyone observed a big difference between SEER/HSPF reported in the Equipment Summary report ( E+/Design Builder) and rated SEER/HSPF ?
I typically enter COP, adjusted by removing fan energy per the equations in Section 11 of ASHRAE Std 90.1-2019. Or, when information is available, I use manufacturers data to calculate COP as a ratio of the cooling capacity and system power, where system power includes only outdoor fan and compressor, at rated conditions.
Either way, the Equipment Summary always reports SEER /HSPF much lower than the rated equipment SEER/HSPF. The difference is significant. For example, a heat pump rated at 16 SEER/ 8.0 HSPF would show up in the Equipment Summary as having less than 12 SEER/5.5 HSPF.
I derived performance curves for several Heat Pumps, but this did not close the gap or mitigate the issue.
Based on conversation with Design Builder support, at some point I believed this may have to do with weather file. However, whatever weather file (location) I run, my SEER/HSPF in the Equipment Summary are always significantly lower than the rated values.
Could someone explain why this might be happening?
Residential projects that I work on typically use Heat Pumps for apartments conditioning (150-300 Heat Pumps per building), so obviously this discrepancy may have a big impact on the energy results for this type of projects.
Any insight, recommendation, comments you could provide would be much appreciated!
Anna
Anna, did you enter the coil model fan performance for SEER calculations? or leave that field blank (which would use the default)?
Hi Richard, Yes , I entered the evaporator fan power w/cfm for this specific HP model. This increased SEER a little bit, but it's still much lower than 16 SEER. I also ran a simulation with my electric resistance heating capacity set to zero, to see if HSPF would change, but it did not. The heating energy went down a little bit, but not as much as I would expect for climate zone 5B.
The only thing I can suggest is to send an idf that looks wrong and include manufacturers data if possible.
Hi Richard, Here is the link to IDF and manufacturer data: https://jordanskala-my.sharepoint.com...
The model has several systems, but only 3 systems (1.5 ton, 2.0 ton, and 2.5 ton) have custom curves: AH R-SW 1.5 TON, AH R-SE 2.0 TON, and AH R-SW1 2.5 TON. Per AHRI ratings, these Heat Pumps-splits should have the efficiency 14.3 SEER2– 15 SEER2 ( 15.0-15.8 SEER) and 7.5 HSPF2 (8.8 HSPF); however, the equipment summary report is showing 13.7-16 SEER and 5.5 HSPF. Any insight you could provide will be much appreciate.
This is a V9.4 input file. Have you considered downloading the latest executable and seeing if the answer is the same? I see the 11.7 SEER for L3XRES:L3XRXSW PTHP DX COOLING COIL but this could be the older calculations, which could have been corrected, or bad performance curves, where did those come from? I tried updating the file to V22.2 and V22.3 but ran into an issue.