I live in a nice little flat in town. I only have: a router on the floor, some tatamis with a futon on them, and a desk with my computer. The problem is that m

I live in a nice little flat in town. I only have: a router on the floor, some tatamis with a futon on them, and a desk with my computer. The problem is that my flat is getting cold these days. I have not enough stuff to "keep" heat with inertia so I need to keep the radiator turned on during day and night. And that's pretty expensive (~€0.18/kWh). That's my minimalist home!