As　the　main　source　of　heat　loss　of　flat-plate　solar　air　collectors　(FPSACs),　single　glazing　cover　reduces　the　thermal　performance　of　FPSAC.　This　situation　becomes　serious　when　the　ambient　temperature　is　low　or　the　inlet　temperature　is　high.　A　double　glass　cover　with　good　thermal　insulation　is　a　good　solution.　This　work　aims　to　investigate　the　thermal　performance　of　double　glazing　FPSAC　at　low　ambient　temperature　and　high　inlet　temperature.　The　thermal　performance　of　four　FPSACs　with　single　glazing　(Model　1),　double　glazing　filled　with　air　(Model　2),　double　glazing　filled　with　argon　(Model　3),　and　vacuum　glazing　(Model　4)　as　the　glass　cover　at　different　ambient　temperatures,　different　heat　transfer　air　(HTA)　inlet　temperatures,　and　different　HTA　volume　flow　rates　are　studied　and　compared.　Result　demonstrates　that　Models　2,　3,　and　4　have　better　thermal　performance　at　low　ambient　temperature　and　high　inlet　tem-perature　compared　with　Model　1.　When　the　inlet　temperature　is　65　degrees　C　and　ambient　temperature　is　-10　degrees　C,　the　thermal　efficiencies　of　Models　2,　3,　and　4　are　1.65,　1.72,　and　2.29　times　higher　than　that　of　Model　1,　respectively.　The　efficiency　factor　and　total　heat　loss　coefficient　of　Model　4　are　0.62707　and　2.21745,　respectively.　(C)　2021　Elsevier　Ltd.　All　rights　reserved.