Method for fabricating a fibreglass product in which melted glass is transformed into a fibreglass product by: ∘ spinning of the melted glass into at least one strand, ∘ drawing of the at least one strand into one or several filaments, ∘ collecting of the filament or filaments, and ∘ optionally one or several of the following steps: ▪ sizing of the filament or filaments upstream from the collection thereof, ▪ drying of the filament or filaments, ▪ gluing of the filament or filaments before or after the collection thereof followed by a cross-linking of the filament or filaments collected glued, and ▪ texturing of the filament or filaments or of the threads containing them method wherein the melted glass is produced in a melting furnace heated via combustion of a fuel with a rich oxidant having an oxygen content from 80% vol to 100% vol, with generation of heat and fumes, said generated fumes being removed from the melting furnace at a temperature between 1000°C and 1600°C, the method being characterised in that: ∘ air is heated via heat exchange with the fumes removed in a heat exchange assembly (20, 21, 22) with the obtaining of hot air, ∘ a reagent (28a, 29a) chosen from rich oxidants and gaseous fuels is preheated via heat exchange with the hot air in the heat exchange assembly (20, 21, 22) with the obtaining of preheated reagent (28b, 29b) and of temperate air at a temperature between 200°C and 500°C, ∘ the preheated reagent (28b, 29b) is used as a combustion reagent in the furnace, and ∘ temperate air coming from the heat exchange assembly (20, 21, 22) is implemented during the transformation of the melted glass into a fibreglass product in at least one of the following steps: ▪ during the drawing of the strand: for the production of one or several drawing gas streams, ▪ during the sizing of the filament or filaments: as a spraying agent of a sizing agent, ▪ during the gluing of the filament or filaments: as a spraying agent of a gluing binder, ▪ during the drying of the filament or filaments: as a drying agent, and ▪ during the texturising of the filaments or of the threads containing them: as a texturising gas stream ∘ spinning of the melted glass into at least one strand, ∘ drawing of the at least one strand into one or several filaments, ∘ collecting of the filament or filaments, and ∘ optionally one or several of the following steps: ▪ sizing of the filament or filaments upstream from the collection thereof, ▪ drying of the filament or filaments, ▪ gluing of the filament or filaments before or after the collection thereof followed by a cross-linking of the filament or filaments collected glued, and ▪ texturing of the filament or filaments or of the threads containing them ▪ sizing of the filament or filaments upstream from the collection thereof, ▪ drying of the filament or filaments, ▪ gluing of the filament or filaments before or after the collection thereof followed by a cross-linking of the filament or filaments collected glued, and ▪ texturing of the filament or filaments or of the threads containing them ∘ air is heated via heat exchange with the fumes removed in a heat exchange assembly (20, 21, 22) with the obtaining of hot air, ∘ a reagent (28a, 29a) chosen from rich oxidants and gaseous fuels is preheated via heat exchange with the hot air in the heat exchange assembly (20, 21, 22) with the obtaining of preheated reagent (28b, 29b) and of temperate air at a temperature between 200°C and 500°C, ∘ the preheated reagent (28b, 29b) is used as a combustion reagent in the furnace, and ∘ temperate air coming from the heat exchange assembly (20, 21, 22) is implemented during the transformation of the melted glass into a fibreglass product in at least one of the following steps: ▪ during the drawing of the strand: for the production of one or several drawing gas streams, ▪ during the sizing of the filament or filaments: as a spraying agent of a sizing agent, ▪ during the gluing of the filament or filaments: as a spraying agent of a gluing binder, ▪ during the drying of the filament or filaments: as a drying agent, and ▪ during the texturising of the filaments or of the threads containing them: as a texturising gas stream ▪ during the drawing of the strand: for the production of one or several drawing gas streams, ▪ during the sizing of the filament or filaments: as a spraying agent of a sizing agent, ▪ during the gluing of the filament or filaments: as a spraying agent of a gluing binder, ▪ during the drying of the filament or filaments: as a drying agent, and ▪ during the texturising of the filaments or of the threads containing them: as a texturising gas stream