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      Best mini-split for a basement

      Usually a 15,000 BTU mini-split for a half basement of about 700 sq ft in a mixed climate. A finished basement is surrounded by cool earth, so it needs less cooling and less heating than an above-ground room of the same size, but humidity control matters more.

      What size for a basement?

      Small basement room ~400 sq ft

      Half basement ~700 sq ft

      Full basement ~1,000 sq ft

      Assumes good insulation and a 8 ft ceiling, typical for a basement.

      Best 15,000 BTU mini-splits for a basement

      Most efficient overall

      Fujitsu AOUH15KZAH1

      15,000 BTU mini-split · AIRSTAGE H-Series · cold-climate certified

      SEER2
      27.5
      HSPF2
      12.7
      Heat at 5°F
      21,000

      Highest seasonal cooling efficiency (SEER2), then heating (HSPF2).

      Full specs and running cost

      What to look for

      Size it for your basement

      Pre-filled for a half basement. Adjust the area and pick your city.

      Your space
      Your climate
      Mini-split size
      15,000 BTU
      Central / ducted size
      1.5 ton
      Cooling load
      14,400 BTU/h
      Heating load
      8,400 BTU/h

      See 15,000 BTU mini-splitsSee 1.5-ton central heat pumps

      Rule-of-thumb estimate: cooling follows the ENERGY STAR room sizing table, heating uses typical BTU per square foot for the climate (NOAA 1991-2020 heating degree days). For a whole-house system, ask your installer for a Manual J load calculation.

      More detail

      Top 5: best for heatingRanked by seasonal heating efficiency (HSPF2)
      #ModelSEER2EER2HSPF2COP at 5°F
      1Fujitsu AOUH15KTAP128.715.413.02.52
      2Fujitsu AOUG15LZAS125.313.912.82.52
      3Fujitsu AOUG15LZAH125.313.912.72.34
      4Fujitsu AOUH15KZAH127.514.812.72.10
      5Panasonic CS-XZ15AKUAW/CU-XZ15AKUACalso sold as 1 other model number22.413.412.02.14
      Top 5: most efficient overallHighest seasonal cooling efficiency (SEER2), then heating (HSPF2)
      #ModelSEER2EER2HSPF2COP at 5°F
      1Fujitsu AOUH15KTAP128.715.413.02.52
      2Fujitsu AOUH15KZAH127.514.812.72.10
      3Century A-ZHP15SA-127.013.011.02.00
      4MDV MOX430-15HFN10-M1Halso sold as 2 other model numbers27.013.011.02.00
      5Mitsubishi Electric MUZ-FX15NLHZalso sold as 1 other model number25.914.711.02.06
      Top 5: best for cold wintersCold-climate certified, ranked by efficiency at 5°F
      #ModelSEER2EER2HSPF2COP at 5°F
      1Fujitsu AOUH15KTAP128.715.413.02.52
      2Fujitsu AOUG15LZAS125.313.912.82.52
      3Lennox MWLD015S6S-1Palso sold as 3 other model numbers23.014.611.02.50
      4Fujitsu AOUG15LZAH125.313.912.72.34
      5York YRACGJ15WHAAalso sold as 1 other model number22.013.011.02.25
      Running cost of a typical 15,000 BTU unit$385-$786/yr

      If used like living space all year; part-time use costs proportionally less.

      Questions3
      What size mini-split do I need for a basement?
      For a half basement of about 700 sq ft, around 15,000 BTU in a mixed climate like Atlanta. Small basement room: 9,000 BTU; Half basement: 15,000 BTU; Full basement: 18,000 BTU. The table above shows how this changes in hot and very cold climates.
      How much does it cost to run a mini-split in a basement?
      A typical 15,000 BTU unit costs about $413 a year in Phoenix, $385 a year in Atlanta, $786 a year in Minneapolis if used like a living space all year. Part-time use costs proportionally less.
      What is the best mini-split for a basement?
      For a 15,000 BTU unit, the Fujitsu AOUH15KTAP1 ranks first on heating. All rankings use ENERGY STAR certified ratings.

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