SPOILER … This experiment didn’t work! See the Comments section.
With summer temperatures looming, so have thoughts about refrigeration. We don’t have any sort of fridge. For most of the year – autumn, winter and spring – this is much less of a problem than it might at first appear. Most dairy products last well enough at yurt temperature that they’re eaten before they go off. Milk that does turn can be turned into cheese and when we occasionally buy meat it’s eaten right away. But summer? Well that’s a different matter.
It’s the noise factor every bit as much as environmental considerations which has stopped me pursuing any electrical solution (though we did have a brief flirtation with an on-offer-in-Lidl 12V camping fridge last year which was so inefficient it was a relief when it packed in completely after just 2 weeks). The thought of sharing a yurt with a humming fridge is just … no. And it’s not like humanity hasn’t lived quite happily for millennia without them.
I started looking at low tech solutions based on cooling by evaporation like Zeer pots. At which point I wondered how I could ever have so much as considered an electrical fridge in the first place.
But suitable earthenware pots of a sufficient size are not particularly cheap, even if less than an electrical fridge, and I wanted to experiment with ideas that could be adapted to be built into a kitchen when we eventually get to the point of fitting one out. But how to replicate a Zeer pot in a box shape?
Portuguese clay building bricks or tijolos! (These are quite different to building bricks we’re used to in the UK. They’re too fragile – and are not designed – to be load-bearing.) They’re cheap as chips. And they even come with cells ready made to fill with the sand.
So the experiment begins …
In anticipation of the amount of clay-based insulation, plastering, earthen floors and cob construction we’ll be doing, I took a delivery of clay from the local brick factory back at the beginning of May. The track was impassable at the time thanks to a combination of forestry operations and rain, so after a quick phone call to the presidente, the quarry truck left its 12m3/17-tonne load at the lixo, the rubbish tip/materials storage area belonging to the local freguesia (council). We’re still waiting for our local man-of-many-machines to bring it along to us with his tractor and trailer, but it’s been ploughing time …
But I didn’t need much more than a couple of large buckets for this project.
Breaking up the dry clods of clay for soaking.
Soaked clay and clay slip being added to sand. This is in the ratio of just under half a bucket of clay to one bucket of sand, giving a rough 30% clay/70% sand mix
After mixing the clay and sand together well, I added a bucketful of horse hair for fibre. This came from a local Shetland pony’s spring moult. Thanks Gypsy!
Treading the mix well to incorporate the hair in standard cob-mixing style.
The mix after being well trod for about half an hour. At this stage, turning it onto itself by pulling over a corner of the plastic sheet results in a nice clean sheet with none of the mix sticking to it.
A close-up shows the horse hair is evenly incorporated.
Dry-stacking the tijolos to work out the dimensions. Tijolos come in many shapes and sizes. These are 30x20x11s.
Plastering the base after leveling the tijolos.
First course in place.
Lining the interior with a layer of clay plaster.
Sand added to the inner cells. I’m going to see how well this works first. Water was poured into the cells to wet the sand and slow down the drying of the plaster and the whole thing was covered in plastic. It was going to be a few days before I had time to do the next layer.
Second layer on and plastered inside and out. The tijolos are staggered to form a stronger structure. This means the cells don’t match up exactly all the way through from top to bottom, but they overlap well enough to work.
Sand added to the top layer.
Now it remains to let the plaster dry (slowly, to minimise cracking) and then test it out. If it works well enough, then I have an idea involving some dripline irrigation pipe for keeping the sand moist …