G’Day HG
When I was selling in the CBD in Melbourne the concept of ‘borrowed light’ was frequently used
This enabled bedrooms to be placed inside flats and apartments and let the windows illuminate and ventilate the living area
For smaller units, such as student accommodation, this was very important as these units were often less than 30 square metres.
Bedrooms get quite humid which can lead to mould, but nonetheless it is important that the room can be closed.
Installing the old fashioned plaster wall ventilators in the wall to the living area should provide enough passive air flow to clear the room even if closed. Of course, if the air can get through so can the sound so you may want to think this through a bit more.
Some units use the concept of fixed partitioning with sliding panels to complete the wall. This provides visual screening but is also not sound proof
The most effective which I saw were fixed partitioning ie stud framed walls with plasterboard, a standard swing door with a handle in a proper door frame, and along the wall above the door height the wall would be glass. This could be ripple glass for privacy but avoid frosted glass as the light is diffused and the room can be gloomy.
If you are modifying a unit in a high rise building, be aware that there are reasons why the unit is 2 bedrooms with a study alcove.
This is because the building is designed to accommodate a certain number of people.
The floor loading, the sewerage and drainage, the ventilation, fire regulations, sound transference etc are all for a certain occupancy.
If you increase the available accommodation you are effective increasing the potential population of your unit from 4 adults to 6 adults. If everyone did this the building and amenities could be put under stain
Inside a unit is private property, but this does not provide impunity from adhering to building regulations.
Remember that an illegal modification to the building could be required to be removed.
Having said that, I have seen some very stylish and effective uses of borrowed light. If your unit is not in a high rise, then there really should be no trouble to convert the space as you have described.
Cheers
Kristine