Seasonal Energy Efficiency Ratio (SEER) and Integrated Part-Load Value (IPLV) are two different ways of measuring air-conditioner efficiency. SEER measures the average cooling efficiency over a specific season while IPLV represents the efficiency in a hypothetical season. The IPLV would be the best-case efficiency for your unit while the SEER is a basic measure of recent data. To convert the SEER to IPLV, you need the four EER coefficients that went into the SEER average. It would be rare to see a SEER without the EERs that made it as well, though, so this should be easy to track down.
Write down the four EER coefficients that made the SEER average. They will probably be listed right where you saw the SEER. Because the SEER is the average of the EERs, you cannot extrapolate the coefficients from the SEER on its own. The EER coefficients will be the rates for the unit at 100 percent power, 75 percent, 50 percent and 15 percent.
Plug the four EER coefficients into the following formula. A is the 100 percent EER; B is the 75 percent EER; C is the 50 percent EER; and D is the 25 percent EER.
1/(0.01/A + 0.42/B + 0.45/C + 0.12/D) = IPLV
Run the calculation on a calculator. The output, as indicated by the equation, is your IPLV.