The　application　of　evaporative　cooling　technique　is　getting　more　and　more　attention.　The　aim　of　the　work　is　to　propose　a　hybrid　air-conditioning　system.　The　hybrid　system　employs　an　indirect　evaporative　heat　exchanger　(IEHX)　as　a　pre-cooling　unit　that　is　operated　in　tandem　with　conventional　air　handling　unit.　The　present　work　has　developed　a　numerical　model　by　considering　the　pre-cooling　effect　of　the　IEHX.　The　IEHX　is　able　to　adopt　the　room　exhaust　air　as　its　working　air.　In　addition,　the　mathematical　formulation　for　the　conventional　cooling　coil　has　been　developed　to　study　the　influence　of　the　pre-cooling　effect　on　the　chilled　water　temperature.　The　calculated　results　have　demonstrated　the　ability　of　the　evaporative　pre-cooling　unit　to　cool　and　dehumidify　the　ambient　air　under　humid　tropical　climates.　The　chilled　water　supply　temperature　can　be　also　raised　due　the　pre-cooling　process.　Consequently,　an　improvement　on　the　coefficient　of　performance　for　the　chiller　is　achieved.　The　hybrid　system　is　able　to　obtain　a　potential　energy　saving　as　a　result　of　the　pre-cooling　effect　and　the　enhanced　efficiency.　©　Springer　Nature　Singapore　Pte　Ltd　2020.