Two buildings, located side by side, are to be designed to prevent the occurrence of fire in any

one of them due to the fire in the other building. The building code stipulates that ASTM E$-119$ fire

is to be followed and the maximum duration of fire that can occur in the building is $30$ minutes.

Find the minimum distance between two buildings so that ignition does not occur in the second

building due to fire in the first building. Assume the following in the analysis:

Emissivity factor $=0\mathrm{.}9$

Stefan$-$Boltzmann constant $=5\mathrm{.}6710-8\frac{W}{m^2}{K}^4$ and

Maximum radiant heat flux $=12k\frac{W}{m^2}.$

Opening $($window$)$ area $=33m$