Use this guide to give you an approximate air conditioning unit size in British Thermal Units (BTUs). New or Well Insulated Villa: Room Size Ceiling Height Factor Kw Required BTU Value Recommended Aircon Unit 4x3m Room 2.4m Ceiling = 28.8m³ x 55watts per m³ = 1.6 Kw 5000 7000BTU 4x4m Room 2.4m Ceiling = 38.4m³ x 55watts per m³ = 2.1 Kw 7168 9000BTU 4x5m Room 2.4m Ceiling = 48.0m³ x 55watts per m³ = 2.6 Kw 8875 9000BTU 5x5m Room 2.4m Ceiling = 60.0m³ x 55watts per m³ = 3.3 Kw 11265 12000BTU 6x5m Room 2.4m Ceiling = 72.0m³ x 55watts per m³ = 4.0 Kw 13652 12000BTU 6x6m Room 2.4m Ceiling = 86.4m³ x 55watts per m³ = 4.7 Kw 16041 18000BTU 6x7m Room 2.4m Ceiling = 100.8m³ x 55watts per m³ = 5.5 Kw 18772 18000BTU 7x7m Room 2.4m Ceiling = 117.6m³ x 55watts per m³ = 6.5 Kw 22185 21000BTU 7x8m Room 2.4m Ceiling = 134.4m³ x 55watts per m³ = 7.4 Kw 25256 24000BTU 8x8m Room 2.4m Ceiling = 153.6m³ x 55watts per m³ = 8.4 Kw 28670 Old Poorly Insulated Villa or Lots of Glass: Room Size Ceiling Height Factor Kw Required BTU Value Recommended Aircon Unit 4x3m Room 2.4m Ceiling = 28.8m³ x 65watts per m³ = 1.9 Kw 6485 7000BTU 4x4m Room 2.4m Ceiling = 38.4m³ x 65watts per m³ = 2.5 Kw 8533 9000BTU 4x5m Room 2.4m Ceiling = 48.0m³ x 65watts per m³ = 3.1 Kw 10580 9000BTU 5x5m Room 2.4m Ceiling = 60.0m³ x 65watts per m³ = 3.9 Kw 13310 12000BTU 6x5m Room 2.4m Ceiling = 72.0m³ x 65watts per m³ = 4.7 Kw 16041 18000BTU 6x6m Room 2.4m Ceiling = 86.4m³ x 65watts per m³ = 5.6 Kw 19113 18000BTU 6x7m Room 2.4m Ceiling = 100.8m³ x 65watts per m³ = 6.5 Kw 22185 21000BTU 7x7m Room 2.4m Ceiling = 117.6m³ x 65watts per m³ = 7.6 Kw 25938 24000BTU 7x8m Room 2.4m Ceiling = 134.4m³ x 65watts per m³ = 8.7 Kw 29693