I think you nailed it. The DOE SACC/CEER rating system provides more realistic numbers for comparing portables to window units, but the assumption of a small te

I think you nailed it. The DOE SACC/CEER rating system provides more realistic numbers for comparing portables to window units, but the assumption of a small temperature differential gives single-hose units and unfair advantage over dual-hose units. A single-hose AC is like running your car AC on fresh air mode, it cools faster if the inside of the car is hotter than outside, but it can only drop the interior temperature so far below ambient. In case anyone is interested, I did not end up returning my single-hose unit, but I did end up buying a dual-hose Whynter ARC-122DHP [0] for another room. It came with a yellow energy guide card listing a cooling capacity of 12000 BTUs and an EER of 11.1, which indicates an average power draw of just 1081 watts (EER=BTU/watt). Unfortunately no SACC or CEER rating was listed. Actually measuring power shows that it draws the full 1200 watts on startup, quickly drops to around 1100 watts, and then slowly drops to 900 watts as the room temperature falls. For comparison, my 8000 BTU (unknown EER, 6000 SACC, 6.5 CEER) single-hose Toshiba RAC-PD0812CRRU [1] also draws 1200 watts on startup, quickly drops to around 900 watts, and then slowly drops to 800 watts as the room temperature falls. So it seems like the dual-hose is around 20-30% more efficient (in a different room under arbitrary conditions) based off the BTU rating, but no better based off the SACC rating. I also noticed that it did not come with foam seals for the window bar like the single-hose unit did, so there is probably room for some efficiency gain there. [0] https://www.whynter.com/product/whynter-elite-12000-btu-dual-hose-digital-portable-air-conditioner-heat-drain-pump/ https://www.whynter.com/product/whynter-elite-12000-btu-dual... [1] https://www.toshiba-lifestyle.com/us/Room-Air-Conditioners/Portable-A-C/8,000-BTU---6,000-BTU-SACC-Portable-Air-Conditioner-with-Remote-Controller https://www.toshiba-lifestyle.com/us/Room-Air-Conditioners/P...