One of the problems we discovered with using old double glazed windows is that well, they aren’t always terribly good at keeping heat in. Even lined curtains can only do so much, and our strawbale and earth plaster walls don’t lend themselves to having shutters attached. So when I visited a house in Cork and saw this idea, I knew it was perfect for this place.

Make some simple 1ish inch frames to fit inside your window openings. They want to be a good but not tight fit. Brace the corners – I used thin plywood offcuts.

Next you need something to go in the middle. Sheepswool insulation is good, or in our case, old duvets, cut up to fit. You can make them single or double thickness depending on your frames. Staple them into the frame, making sure they are well attached all the way around.

Now cover with fabric. Your old curtains are ideal, but upholstery fabric or whatever you fancy.The fabric around the edges of the frame should make them a snug (and airtight) fit into the opening. If they are a good fit then you’ll probably want to screw some sort of handle on the inside so you can get them back out of the window again.

We just keep ours in the corner of the room and pop them in at night. It makes a really big difference to the amount of heat retained in the room.