Is Viridian PyroGuard40™ the only glass which can used in bushfire resistant glazing?

No. The Australian standard for glazing in bushfire prone areas (AS 3959) also allows various thicknesses of toughened glass to be used in glazed areas. However, because of the inherent weaknesses of toughened glass when exposed to high radiant heat loads and its potential for breakage from airborne objects, the glass, in some cases, must be protected by metal screens in both operable and fixed windows.

Viridian PyroGuard40™ however, does not need to be protected by steel screens in fixed window applications. Operable windows must be protected by screens to prevent embers from the bushfire entering the house if the windows are left open.