The model House (Large, Abandoned) [Land_u_House_Big_01_V1_F] has at least one window that does not let grenades pass through. This "window" is simply a cut out in the wall and has no grill or anything obstructing it. Bullets can be fired through, however grenades, chemlights, etc. bounce back as if they're hitting a wall.
This window is located on above the back entrance.
UPDATE: ALL windows in this model block grenades.