The existing windows in the ADU were installed in 2009 and are double-paned vinyl. New to match. It was previously unheated, but we want to add an electric wall heater. Supposedly the walls on the (e) office area are R-13 and the ceiling R-19. I have a call into the contractor to verify and I will let you know when I know for sure. Originally this little shack was built in the 50s.