A vacuum insulating glazing unit has a length equal to or greater than 800 mm and a width equal to or greater than 500 mm. The unit includes first and second float annealed glass panes having thicknesses Z1 and Z2, respectively. The thickness Z2 is equal to or greater than 4 mm and equal to or greater than (λ−15 mm)/5. The thickness ratio Z1/Z2 is equal to or greater than 1.10. The unit also has a set of discrete spacers positioned between the first and second glass panes and forming an array having a pitch (λ) between 10 mm and 40 nm; a hermetically bonding seal sealing the distance between the first and second glass panes over a perimeter; and an internal volume having a vacuum pressure of less than 0.1 mbar.