Could be anything.
I quite like the fireplace idea, but why the fancy painted shape?
Plus some dodgy looking wiring.
I can see it's low voltage, but cables and carpet Smoothedge don't mix.
That floor is crying out for nice thin ply overlay.
An awful lot of drafts come up through floorboards, especially around the skirting board.
I also like to add a covering of metallised film for a bit of insulation and moisture barrier.
Space blankets are the cheapest source.