Our home is a 1950s house which is hard to keep warm despite central heating, a loft full of insulation, double glazing, and cavity wall insulation. The unheated kitchen and conservatory on the back of the house act as a huge heatsink sucking warmth out of the house in winter.
Last year I bought a 10m X 2.5m roll of fleece fabric from Empress Mills, and set about using it as insulation. I lined the lounge curtains, bought a used curtain pole from a neighbour through Nextdoor and made curtains to go across the middle of the lounge.
We can now draw the curtains and make a warm zone in the lounge instead of losing heat and wasting energy. Result!