Sorry a few backers had asked me about default/recommended scale to print these and such. Unfortunately I did not have this in mind when designing these which I will start keeping that in mind from now on. Reason being I could scale them later since I knew the width, height and depth of the models when I open them in the slicer program. What I had in mind was, I knew the height of the building, for example the height of the door, then I would know how much more to scale up the building in order to look proportional to the minis.
As of Jan 06, I have re-scaled majority of the models with doors/entrances to have a door/entrance height of 20mm, hopefully this will make everyone's life a bit easier when scaling up and down for his/her own games.