Well, we have a lot of problems in your file to start with. First you where using area lamps to illuminate your scene. That should not be a big deal, if the scale was different and area lamps for exterior renders can be a source of noise. You should have used an environment map. I’ve applied the nishita sky map and it helps a lot.
Second, your glass has no thickness. The mesh has to have a face where the light comes in and another where it goes out, otherwise the refraction will be messed up. I’ve applied a solidify modifier to solve that.
Also the material of the glass was not assigned to the glass faces.
What version of blender are you using?
I also realized that your roof and ground have no thickness and you messed up with sub surface scattering values for the walls. I have fixed all this issues, added denoiser and selected GPU rendering.
Added a ground and now the things are a bit better.