DIALux

As a recommendation, DIALux is quite a handy tool for both light calculations and visualisation. It’s completely free, completely easy and you can download it here.

On youtube, there’s lots of fancy videos made with DIALux by some saudiarabian guy, nevertheless I’m going to link to this one called “My first dialux project”, I think one can achieve a similar simulation in a day with default furniture, windows and downloaded light sources that most larger producers provide.