I had this thought 4 years ago just as I was renovating our new home. After tonnes of research, I had settled on getting carbon electric paint for our ceilings to act as energy-efficient, space-saving, highly controllable, instant electric radiators. The intention was to keep our home warm in the winter months using just passive daylight solar power which would heat up all our internal surfaces to keep them cosy for human usage as if they were storage heaters like floors, walls, and kitchen worktop surfaces. That all fell through we we could not even find an installer of the technology within a 50 mile radius.