EER does not account for heat infiltration issues, so this seems confused. CEER does, and that does suggest something in the 20% range, but I am pretty sure you can’t use EER to compare a single-hose and a dual-hose system.
All portable air conditioner’s energy efficiency is measured using an EER score. The EER rating is the ratio between the useful cooling effect (measured in BTU) to electrical power (in W). It’s for this reason that it is hard to give a generalized answer to this question, but typically, portable air conditioners are less efficient than permanent window units due to their size.
For example, a 14,000 BTU model that draws 1,400 watts of power on maximum settings would have an EER of 10.0 as 14,000⁄1,400 = 10.0.
A 14,000 BTU unit that draws 1200 watts of power would have an EER of 11.67 as 14,000⁄1,200 = 11.67.
Taken at face value, this looks like a good and proper metric to use for energy efficiency. The lower the power draw (watts) compared to the cooling capacity (BTUs/hr), the higher the EER. And the higher the EER, the better the energy efficiency.
Thus, if we were to look at the EER of the two example units above we could easily say that the second has better energy efficiency because it has a higher EER – 11.67 compared to 10.0.
However, taking into account what you’ve learned so far about the old method used to determine cooling capacity (standard BTUs) vs the new method used to do so (SACC), you should be able to spot one major problem with EER. That’s right. It uses standard BTU’s – yes, the old BTU metric – in its equation.
The Department of Energy also recognized this issue with EER and acted accordingly by instituting a new metric by which to determine a portable AC unit’s energy efficiency.
That metric is called CEER – Combined Energy Efficiency Ratio.
Unfortunately, CEER is a lot more complicated than EER. The new energy efficiency ratio could have simply involved taking SACC and dividing it by maximum power draw on cooling mode in watts. But the DOE decided that the equation needed a little bit more nuance than that. Let’s take a look at the end result:
EER measures performance in BTUs, which are simply measuring how much work the AC performs, without taking into account any backflow of cold air back into the AC, or infiltration issues.
EER does not account for heat infiltration issues, so this seems confused. CEER does, and that does suggest something in the 20% range, but I am pretty sure you can’t use EER to compare a single-hose and a dual-hose system.
I assumed EER did account for that based on:
This article explains the difference: https://www.consumeranalysis.com/guides/portable-ac/best-portable-air-conditioner/
EER measures performance in BTUs, which are simply measuring how much work the AC performs, without taking into account any backflow of cold air back into the AC, or infiltration issues.