food&beverage&bio hacking activities

Hexayurt Cold Room at OHM2013

“Tak jak to tenkrat bylo” as we say in Czech, “how was it than?” or in Dutch, ” Hoe ging dat nou eigenlijk?”
The  construction of the hexayurt cold room (hcr) was well prepared, long  term disorganized effort of the Food Hacking Base (fhb) aimed to store  “perishable items” against the Dutch summer sun (yes such thing truly  exists, and to the Dutch, please be quite!) at the OHM2013.
So after few months of poking variety of the mailing lists especially the ohm2013 discuss, we actually decided that even after successful crowdsourcing campaign we do not have enough money and especially manpower for the endeavor, so lets skip it. When I arrived to the camping ground on 23.7.2013 with not a single tent erected (with exception of Thorsten’s one, you know how the German guys are …), I have found out during day or two that the OHM2013 orga actually would like to support the hexayurt cold room project with up to €1000 budget. Within few seconds I said yes and we were in the game.
At this point lets summarize so you do not waste your time if you do not want to (I think you should by the way). We build the hcr up based on the 12′ hexayurt design inspired by Vinay Gupta’s work, Samuel had several nice suggestions on the project, more info here. We installed and hacked the air-con and stored our perishable ingredients going down to 12°C during the night (below 20°C outside) and 16°C during the day (above 30°C outside). The “hot party” on the last day of the camp is completely non related story but yes it was nice and “hot” … So in other words cool but not cold as we wished, to improve that for next time stronger air-con split unit with around 30 000 BTU capacity should be used (compared to 10 000 BTU mobile air-con which we had).
Now back to the story and the build up. Our major problems for the project could be said were three. First we had an issue to find European style wooden pallets for the foundations, which may seem trivial but well it is hard to start to build something when the foundations are missing right? Sorted, many thanks to the orga although they did not really know … Second we have had a major issue to get a good quality insulation material anywhere close by which could be used to build a self relaying structure without worrying about collapsing, sorted, many thanks to Daan for finding it and  Thorsten to drive us there and back! Third and last, the air-con was up to €400 expense if bought new, which we sorted with €120 purchase of old one, later on realizing being unusable because all the Dutch service man who were the only people allowed to reload it (and possessing the cooling gas) were too busy or on a holiday. Many thanks to Braam who got us his last minute saver 10 000 BTU mobile unit and Marcel for picking it up.
Summarized – when you decide to build your own hexayurt cold room pay attention to what insulation materials and for what price you can get in the area where you are building, where you get powerful, cheap enough and functional cooling unit and simple but basic, what are you going to build it on and that you have that first. Also having someone to take pictures during the progress comes handy, for our project Marcel and definitely Eric has to be thanked too, plus others!
Well time to get into the details. The foundations for the 12′ hexayurt were build with 12 standard European pallets which were made more or less equal directly on the lawn. Some of the pallets had to be bit rebuild because they were not sturdy enough. This took us around two hours. When done we used 18mm thick chip boards for floor, the type which is used to make floors on building sides, having an “outer line” on the edge which slides into the “hole line” on the other side of the board. The assembly was done within more or less 3-4 hours within 2-4 people team involving Marcel, Thorsten, Stuart, Lars (well most of the Warpzone) Erwin and Eric, Christian, Lurwah and others discussing and relaxing in the meanwhile. The walls, ceiling and doors were made from (secondhand) polyisocyanurate insulation boards (PIR, used in cold-cells, cardboard/fabric/reflection outerlayer), dimensions close to the usual plywood boards – 2.4 to 1.2 m and 10 cm thick, double aluminum layered, the R-value above 4. Again the boards had the edges which fit into each other which helped us a lot. To erect the walls we needed around eight people at the time because it was a real windy day (5 bft. in an open landscape). We sacrificed some volunteers and left them inside, got them out after an half an hour or so, when we cut the doors in one of the walls, using the cut out later on as door based on the “cork style” approach. The walls were up within two to three hours and as soon as the full circle was made they were able to stand up in the wind without support, later on, we added a two straps fully around, just to be sure.
The next step was the roof and it was quite an adventure, supervised by Daan. Because the walls did not fit perfectly we were improvising a bit managing however at the end to make it happen quite in a decent way, it took several hours to put it up with several people involved. For the seams all around the structure we used polyurethane foam supplied by Daan and also the “cloth” protecting coating from the insulation panels. The top of the cold room was covered by large tarp because we did not have time to make it waterproof (next time we will use some30cm’s wide cloth or tape and make the seams perfect..).
The mobile air conditioning unit was the weakness of whole project (as we have been informed by the Indian expert camping across the street) but it allowed us to make it happened so definitely many thanks to Brann for his help on this one otherwise we would be done. The air-con was disassembled, the temperature sensor identified and moved to the heat exhaust so it was constantly overheating, making therefore the air-con cooling all the time. The fan of the air-con had 2 settings: low and high. At the beginning, when the aircon frozed the fan was on low setting. When we
switched it to high, we did not have any more problems with ice. Whole aircon was placed inside, close to the corner which bottom we left open so the air from out can get in, air-con taking the air from the cold room and cooling it down, expulsing the hot air out by the duct in which the temperature sensor was placed. The doors were made from off cut of the insulation material with two door handles attached by rope going through the holes in the board. The last improvements were light made by Lars, which was a PC-Cooler with 3 10W warm white LEDs on it, worked grate! The floor was insulated by a thin aluminum foil with carpet made from green plastic grass like material on the top. We installed weather station which had the temperature and humidity sensor both inside and outside of the cold room, reporting the readings online (can not find the link to the data now).
If man-hours should be counted, most likely 4-5 man can build up this structure within one and half to two days in a quite pretty relaxed way if most of the tools and materials are ready.
During the usage of the cold room we run into troubles of overheating the room which was caused by buildup of the ice on the air-con cooling system. To avoid that we switched the air-con off once in few hours for half an hour or so which helped, the water from the ice melted on the floor which was not the best. During hot days we managed to keep the temperature under 16°C (outdoor temperature above 30°C) and during the night below 12°C (outdoor temperature above 20°C, sometimes below) with entering the cold room nearly every half an hour or so.
It took around 2-3 hours to take the cold room apart at the end of the event, many thanks especially to Thorsten, Erwin, Marcel and Stuart for the help! I’ve to apologies here especially to the orga for leaving a lots of waste (building material) behind us after our construction projects. I do consider it partly misunderstanding because I did not managed to find out what is the procedure at the end of the camp concerning waste removal, it was really not intended. The orga took care of that for us, again apologies here, we have covered the related expanses not the volunteer work. Next time we need to sort out the transport of the material to some needy hands and dedicate some resources to that.
For the next cold room project it is recommended to have either one more powerful split air-con unit or two split air-con units (second case could be better to prevent the ice build up if programmed properly), make sure that the structure is water proof, using some lino on the top of the floor for easy upkeep, improving the door system, preferably building the double door (or transition chamber) and definitely building up some shelves so the capacity of the room is bigger and it is more easy to organize and access the things.
All in all the project was done with a team spirit, it tested a lots of things in reality, serving as a good start for next project of this type, the aim should be to go below 10°C at all the times.
Many thanks to everyone involved especially those who are not mentioned here, there were many of them!
Food Hacking Base

One response

  1. Pingback: FHB at OHM2013 | foodhackingbase

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