Maybe it's some sort of convertible note system based on the monthly value of the building? So, $1k / month for a year is the equiv of a $12k convertible note? Ideas?
This will be a complex financial model. I'll see if I can come up with some stable form of transaction agreeable by both sides. If you require any assistance on this, drop me a line at subhankar.sett which is in gmail. I'll try my best.