Once I found out that owning a dog is the carbon count equivalent to taking an aeroplane flight every year, I resolved to think what I could do to up-cycle my tin cans, rather than just recycle. So I started saving them – or most of them. I stopped buying the plum tomato tins with plastic insides because they are deeply toxic to the human body.
It occured to me that if I punctured the bottoms of empty tins, painted them black and stacked them, leaving them in the sun might generate some heat. So I made a small panel pictured below.
I insulated this with some leftover polystyrene wallpaper and tinfoil that I had stopped using in the kitchen, and installed it on the front door, with a small solar panel driving a computer fan to suck the warm air through. It definitely produced warm air but not enough to warm anything in the 1620 built Cornish granite cottage which seems to be a ‘black hole’ for warmth in the winter.
Now I was in the habit of saving cans, the collection built-up over a couple of years to the extent of generating complaints from my partner. But I had a plan… I was to build a permanent ‘winter yurt’ in the garden and upscale this idea to make self-heating walls from the tins. I can report that when the sun is out in the morning that these two heat generating walls make a considerable difference (I estimate 3-4 degrees celsius but haven’t measured it yet) to the internal heat of the yurt.
There were still many tins left and I was impressed by their structural value. Encasing them in between sheets of polytunnel liner used them for insulation value also – stuffing the tins with something may have increased their insulation value further. I made the wall of one of the 12 sections of the yurt with these, it was out of the sun so the tins didn’t need painting:
I will also be using this wall making technique for my next project in 2018 – the garden composting toilet.