Environmental　conditions　and　mass　flow　rates　both　influence　the　performance　of　hybrid　photovoltaic　thermal　modules.　In　this　work,　the　performance　of　a　photovoltaic　thermal　module　was　investigated　under　two　controlled　laboratory　environmental　conditions:　closed　and　ventilated　air　circulation.　Comparing　two　different　environmental　conditions,　we　have　examined　the　effect　on　operating　temperature　by　the　mass　flow　rate　of　coolant,　varied　over　the　range　0.05　kg/s　to　0.10　kg/s.　Experimental　results,　under　indoor　laboratory　conditions,　indicate　there　is　a　measurable　effect　from　mass　flow　rate　on　the　overall　electrical　efficiency　in　comparison　to　output　at　ambient　temperature.　Interestingly,　the　output　power　and　electrical　energy　of　the　photovoltaic　thermal　module　were　observed　to　increase　by　6.06%　and　3.67%,　respectively,　under　the　conditions　of　ventilated　air　circulation.　In　addition,　the　maximum　electrical　and　thermal　efficiencies　of　the　photovoltaic　thermal　module　were　estimated　as　13.67%　and　53.08%,　respectively.　Results　obtained　in　this　study　provide　a　useful　reference　for　applications　of　PVT　modules　requiring　combined　heat　and　power,　such　as　commercial　buildings　and　building　integrated　design.