Glossary · Heating, cooling & ventilation
Region IV and Region V (HSPF test climates)
Also called: Region IV · Region V · HSPF2 Region V · HSPF2 Region IV
The two climates heat pump heating ratings are usually given for: Region IV, like the Midwest, and the colder Region V, like the northern tier of states.
What it means
HSPF and HSPF2 depend on the winter assumed in the rating calculation, so the same heat pump scores lower for Region V than for Region IV. Spec sheets and the AHRI directory usually show Region IV. Real seasonal efficiency is lower still where winters have more heating degree days.
Why it matters in an audit
Compare heat pumps using the same region's rating, and in the coldest northern states look for the Region V figure.