North facing living room

Following this with interest. We have a north facing room which we never used. I turned it into a sitting room + playroom for my little GC. It’s so cold though. Has a big radiator but wooden floors and it has high ceilings. I want to carpet it but OH is reluctant. I’ve put a cheap rug down for now. I’ve made heavy curtains but they don’t help in the day. We’re having new windows soon so that might help. Current colour scheme is a denim blue chimney breast wall with soft stone walls and ceiling and white woodwork.

I’d go for a wall of paper too,it’ll warm it up then choose a colour from the paper for the other walls,bright cushions and accessories then. I have a south west facing lounge and have grey everything, pink cushions and curtains.

I guess this might not suit you, but just to contribute in case it interests others:
Our north-facing living room is good old 'magnolia', covered with cheerful framed prints - all inexpensive except for one special one - many are birthday cards that we have framed.
Floor is wood, with a couple of colourful rag rugs that I hooked myself (very easy!)
Curtains are a gold dupion with colourful insets (sort of large patchwork!)
Settees are a grey-green, with - you've probably guessed - loads of patchwork cushions made from all sorts of scraps over the years.
It's a colourful mish-mash that suits us!