When exterior insulation fire occurs

windows not only become passageway

which brings flame inside

they also provide considerable amount of fresh air that may cause indoor flashover.In order to study influence of window-wall ratio on fire spreading rate and temperature

this article uses field simulation software FDS（Fire Dynamics Simulator）to simulate residential exterior insulation fire scenarios with different window-wall ratio.It concludes that as the window-wall ratio increases

both the fire developing speed and spreading scope increase

peak temperature however decreases.When window-wall ratio of burning side is 0.25

the peak temperature of measuring point is much higher than other control groups.When the ratio is 0.30

flashover takes place in the burning room.When the ratio is 0.35

sufficient fresh air flows in

then the peak temperature drops.For none-burning side

its characteristic fits above regularity basically.When the ratio is too small（0.20）

it is hard for flame to get to room and therefore the situation is not severe.