I really like to make cold brew iced coffee. I also like to go camping. I developed this method for making cowboy cold brew which works just as well at home or in the woods.
Cowboy coffee refers to mixing the grounds in with the water and then pouring it out through a filter once it has brewed. This is different from the way most people make coffee. With cold brew, there are basically two ways to make it. You can either get a bag to hold the grounds while they brew, or you can do it this way where you just mix the grounds into the water and then pour it all through a filter.
The big difference between these two methods is that you don’t have to deal with dirty bags. The problem there is that if you use a dirty bag again, you are likely to see mold and then you are done making coffee until you can get to a dishwasher and bleach everything.
Doing it cowboy style means your filter stays clean between brewings and doesn’t get moldy.
Let’s Make Some Coffee!
You will want to add two tablespoons of coffee per eight ounces of water. So for one liter of water, that’s about 34 ounces which comes out to about half a cup or four ounces of coffee grounds.
You may have to eyeball this if your Nalgene doesn’t have marks for just four ounces. More is more; you can always add water afterwards to dilute it down. I’m using a 1.5 liter Nalgene in this photo, and I make it a little stronger than normal, so I used eight ounces of coffee grounds in this photo.
Start by putting your grounds and then water into a Nalgene or similar container as shown. Shake it up and stick it in the cooler for about 24 hours.
I’m using a mesh filter here but it has since been discontinued. I would recommend this other one that I also have because it is easy to clean by simply rinsing it. If you get one with cloth, it’s going to get moldy.
Next simply poor your grounds-water through the filter into your clean container…
I’m using a blender bottle. These are really great because they rinse clean with zero effort and they are very sturdy. After many years at burning man dropping it form moving bikes on a regular basis, I’ve never had it come open; really great drink container.
In this case, I just wanted a little coffee at the moment so I transferred it over to my camp cup and left the rest in the cooler. This kind of cold brew will keep in the cooler for up to two weeks. For your used containers just rinse them out and let them air dry. Couldn’t be easier!
I decided to make this post because I have done a super lot of research for this project and I need to keep it all straight and share the results with a few people.
I wanted to do a camping trip for burn week this year because the burn is canceled. I had considered going to the playa anyway but the Elders of the Paiutes have asked that people not do that because it would place a burden and elevated covid risk on the local population which is already at increased risk and lacking vital resources to respond to the pandemic due to centuries of systemic racism and institutional neglect.
So I turned my sights to Tahoe. I’ve been camping there several times in recent weeks, and decided it would be a great place to camp as an alternative burn week. I really liked Tahoe SRA and Nevada Beach Campground.
In July when I made this decision, I checked all the camp grounds in the greater Tahoe area and unfortunately none of them had reservations available for August 28th-September 6th. Luckily there are lots of options for campgrounds which do not take reservations. Though none of these walk-in options provides showers, when I stayed at Tahoe SRA down the road, lots of people showed up after the rangers left for the day to either squat on unclaimed reservations or use the showers, so there are definitely ways to get a real shower if you really want to. But keep in mind that if you’re going to be at the pristine lake all day, you’re going to come back to camp pretty clean.
Walk-In-Only Tahoe Campgrounds
These are developed campgrounds on the lake which do not take reservations. They are first-come, first-serve. So showing up early means you are likely to get a spot. My first choice will be to do lake forest for the first half of the trip (8/14-8/28) and then bayview for the second half of the trip (8/28-9/7).
Bayview Campground: This would be the most ideal option because it’s at the top of the peak surrounding Emerald Bay so it would be an amazing view plus the sites are pretty big and the campground has good reviews.
Lake Forest Campground: This is a great option because it is on the lake and right in the middle of town. Downsides are that it’s close to the noisy main road.
The challenge is going to be showing up in time to get a spot. I would probably shoot to arrive early Thursday morning or Friday morning and it seems very likely that we could get a spot at one of these two campgrounds.
Nevada-Side Primitive Camping
There are lots of primitive campgrounds on the Nevada side of Lake Tahoe. These have restrooms and water but no showers.
North Canyon Campground (Exact Location): This seems like the easiest one to get to. It’s just off the 50 in the mountains above Secret Cove. The linked location shows the campground entrance and the restrooms. If you keep going on this road, there are also two more campgrounds, both also primitive. All three of these campgrounds have bear boxes so that makes things a lot easier. The one downside is that you can’t drive in. You have to walk in, and it’s three miles from the parking lot to the camp sites. Seems extremely likely to have a lot of openings.
One cool thing about North Canyon Campground in Tahoe is that if you Google it, it will redirect you to a campground in nearby Carson City with the same name. There is nothing at all on Google Maps about the real Tahoe North Canyon Campground location. If you go to street view, you can find it where the topographic maps from the park service says it should be, but Google has not heard about it yet. This is very exciting because probably most people will not know about this or be able to find it.
California-Side Primitive Camping
There are a number of lodges called “huts” along the crest of the Sierra Mountains just to the west of Lake Tahoe. I spoke to someone at the Sierra Club which owns the huts, and they said that while the huts are technically not open for reservations because of covid, they are not locked, and water and restrooms are definitely open and available.
Normally dozens of people will sleep together in a large room in the lodge but obviously that’s not safe right now. The Sierra Club is advising that no one sleep inside because of covid risks, but camping outside in a tent is still fine, according to the person I spoke to at the Sierra Club.
Bradley Hut (Exact Location): This is actually on a road just off 89 so it’s on the way to Tahoe from Sacramento and SF. It’s about half an hour from the nearest grocery store and about an hour to secret cove. Everything in Tahoe seems to somehow be about the same distance from everywhere.
Ludlow Hut (Exact Location): This one is a little closer to things, and also it’s right on its own lake, but it’s a bit more of an adventure to get there with only dirt roads that may require some creative navigation.
One more thing to keep in mind about California-side camping is rain shadow. Because of the topology of the lake, basically all of the precipitation comes on the California side. If it’s going to rain, it will probably be in the north-western area of the Tahoe region.
If the lodges are not to everyone’s satisfaction, I am personally very pro-primitive camping on public lands. BLM land is free for camping and you can basically just show up and camp guaranteed; there are tens of thousands of acres available at each trailhead so there is no limit on how many people can camp there. Also it’s sort of unknown and hard so it’s weirdly not something people take advantage of.
There are lots of good spots very close to Tahoe where the Pacific Crest Trail intersects roads and there are services like bathrooms and water. I found a few good examples where we can definitely camp for free as a backup if the two walk-in sites don’t work out.
Granite Chief Wilderness (Exact location): This is about 26 minutes to the nearest grocery store and about an hour to secret cove which is basically the same as the other campgrounds I’ve stayed at in Tahoe. It has a restroom and water.
I am currently planning to spend the previous week at North Canyon and then show up early Friday morning on the 28th at Bayview and try to get a spot. Bayview seems like the all-around best option. If that doesn’t work, I will try Lake Forest Campground, and then probably just go back to North Canyon. If for some reason all the campgrounds do not work out, then Bradley Hut seems to be the best remaining option.
At Burning Man, I camp with Comfort & Joy. One of the many benefits of this camp is that they will transport totes to the playa for you; you are only responsible for getting yourself there. The stipulation is that everyone has to use this same tote.
There are many benefits to this strategy. These totes are very sturdy and stackable. They are easy to zip tie shut. They don’t break open. They can be stacked very high inside the truck without buckling or collapsing.
One downside is that you have to store them all year, along with your playa bike. In San Francisco, this can be a real challenge. Most people are paying as much as they can for a tiny space. San Francisco is a weird place. One weird thing about it is that it is not uncommon to see storage units renting at $10/sq ft across the street from studios renting for ten times that price. A friend and I talked about it and decided to split a storage unit to store this and other stuff.
This is the layout we decided on;
We decided to get a 5′ x 10′ unit which comes out to $125/month. We are going to use six of these shelves which fit perfectly for a space this size. This also leaves a roughly three foot walkway down the middle of the shelves.
These shelves are perfectly sized to fit the 27 gallon totes we have to use for our camp. Then the Shiftpods and other large items can go on top of the shelves. Bikes can go in the walkway.
This plan gives us space for twenty-four totes plus probably half a dozen bikes and space above for more stuff. The rent breaks down to just about $5/tote. More likely, we will only fill the back few shelves in the short term and leave space in front for projects.
We will probably have a lot of extra space at first, so let me know if you want to jump in!
There were a few really cool ideas for shelters and infrastructure in the new season of The Expanse that I wanted to talk about. All are variants of popular, existing styles of shelters in common use at Burning Man and elsewhere. All of these images are from episode 2, 3 or 4 of season four of The Expanse.
Let’s start with an aerial shot that shows all of the things I’ll be talking about…
I was very interested in these geodesic domes which expand out of a container. The container then becomes the door, and contains various electronics, lights, and other accessories for use inside the dwelling. This is a very compelling Burning Man shelter design.
Not shown in The Expanse, but I would also add wheels to this so that one person could easily move it. Maybe the wheels could be on the top or the side so it stays in place once you set it up?
The 3v dome members strike me as unnecessarily complex. I would make them large enough to stretch almost across the container when packed. This would also drastically simplify construction. Something like a 1v icosahedron would be so much less structurally complex while also meaning all the members are the same length. Using identical members is so much easier than keeping track of which member goes where. Even something like an octohedron or just a cube would still look cool while providing excellent protection from any normal conditions. It would be really cool to see a lot of different geometric shapes set up together as shelters.
Check out my post on building microgrids for specifics on how to do power for a small unit like this. There is a lot of potential with this packable dome design for integrating solar and other great tech. I would also use a different material for the dome covering… maybe something like mylar or iridescent plastic glued to canvas or blackout fabric.
HMM I sense a new project coming on.
You can see the structure is placed on an elevated platform. This strikes me as unnecessary unless you’re in a wet climate or a location with pests. At Burning Man, neither of these things is present, so I think it would be fine to skip that step and place the structure on the ground, or incorporate a tarp/waterproof floor which attaches to the covering material.
The second shelter design is a kind of hexayurt. It’s technically an octoyurt as it has eight sides, but it uses the same type of material and structure as a hexayurt. I especially like the geodesics at the top. These seem much simpler to assemble than the popular hexayurt roofs which require half a dozen people working together in order to put them up.
I also really like the windows on the side panels. Something like this would be super cool to use as a little dome window. Very meta while also being very functional.
The third shelter design is a combination of the first two ideas; an octagon which extends in a line out of a container.
The front door is part of a container just like the domes above. The structure seems to extend out from the container, using fabric around a gantry to provide a large internal space. This leaves lots of room for equipment and infrastructure like power, batteries, lights, etc in the permanent front section.
This structure also incorporates the elevated platform into the gantry. Again, this seems unnecessary at Burning Man, but potentially helpful in wet or animal-prone environments.
It also seems that these can be connected together to form networks and larger structures. There are several examples in the show where these expansion octagons and connected together. Here are a couple…
This seems like a very inefficient use of space compared to the geodesics. These octagons are very large when packed, and don’t get much bigger when unpacked. In contrast, the geodesics pack much smaller and offer more inside space when unpacked.
Then again, setting up geodesics is complicated and takes a lot of work. These would just pop up and be done. There seem to be pros and cons to each design.
Simple Water Towers
Water pressure is complicated. At Comfort & Joy, we use a 1kw pump attached to a rented IBC tote which is on the ground. If there is no power, then there is no water. In our case, running water goes to three locations; the showers, the kitchen, and the water team. This could be dangerous if there are any issues with our power grid. We address that danger with the water team I mentioned. Their job is to constantly fill and place dozens of small 5g totes in locations around the camp. This means that even if the power and water infrastructure goes down, there is still lots of water available throughout the camp until the infrastructure is back up.
In The Expanse, there are lots of shots of IBC totes being placed on the roofs of shelters. This eliminates the need for a pump, and eliminates the risk of losing water if you lose power. This seems like an obvious solution to this problem which eliminates a lot of the complexity. It would mean that the water needs to be pumped up into the tote and then pumped out at strike, but the water rental people already do that, so this seems like a really good solution.
Lots of people spend time in tents. As a Burner, I am one of them. There is a big problem which anyone who has ever slept in a tent can relate to. That problem is Thermodynamics.
Thermodynamics is a law of physics which basically says that the heat from the sun will eventually get into your tent. What this means for campers is that even on a day where the outside temperature only gets to 80, it’s going to be 100-120 degrees inside your tent. There are basically two ways to fight back against thermodynamics in this case; put barriers in the way which will slow but not stop the heat getting in, or put something in place to absorb or remove the heat.
For a Chemistry honors project, I am studying the effect of various techniques and materials on prolonging that magical sleeping time in the morning before the temperature inside the tent gets too high to keep sleeping.
I will also be comparing fancy expensive tents to the cheapest alternatives in order to see if fancy expensive tents are actually any better. In this case, I have chosen the very popular Shiftpod v2.0 to compare with a cheap tent of similar design from amazon. I have taken to referring to the blue fishing tent as “Blueshift” for simplicity’s sake.
One thing to keep in mind is that this is not the playa. We do have partly cloudy days here in Sacramento, so there may often be sudden spikes and dips in temperature. These cloud effects will reach both tents, so it will be interesting to see how they each fare with them.
This experiment was done in Sacramento, not at Burning Man. Results will vary but systemic error should be low, since both situations include similar variables such as humidity, sunlight, etc and impact from the different mitigation strategies. I’m planning to do a future version of this experiment at the playa during fourth of juplaya which includes more tent types such as a hexayurt and a pup tent.
The tents are not exactly the same size. There may be some differences in amount of heat reaching each tent. That said, Shiftpods are 1200% the price of the cheaper tent. If it’s worth that, this trivial difference should not matter.
Some of the links on this page are affiliate links. I”m a starving student trying to pay for this expensive experiment. It doesn’t add to your cost if you choose to buy things with these links. I just get a small cut to help cover my costs. If you don’t want to use the affiliate links, you can open them in incognito or something like that in order to remove the tracking code.
I am using a custom built multi-zone temperature logger to track the data. The full details of that can be found here.
Phase 1: The Naked Sun
For phase one of the trial, both tents will be in full sun. This photo shows them at 2pm the day before the data shown. They had a full 24 hours to adjust to the environmental conditions before experimental data collection began.
Like any tent, both the Shiftpod and the Blueshift will eventually get much hotter than the outside temperature when in full sun. The way to win at this stage is by staying cooler for longer. This means the occupant will be able to sleep longer and have a better experience with their tent.
In fact we see that the internal temperature of the Shiftpod hits 100 degrees more than an hour before the Blueshift does. At 9:30 in the morning, that crucial time for sleep, we see the Shiftpod more than 15 degrees warmer than the Blueshift. By 10:45, it has passed 100 degrees. The Blueshift doesn’t hit 100 until after 11:45.
At this point, I suspected a possible reason for these surprising results. The Blueshift has a single layer of thin waterproof fabric, where the Shiftpod has a thick layer of air-tight insulating fabric. I suspected that this thick insulation could be trapping the heat where the Blueshift will let that heat escape.
This could explain the difference in temperatures, and imply that Shiftpod themselves intend users to take additional measures in order to reap potential benefits of the materials they use. Air conditioning for example would make that insulation helpful rather than harmful. This would also explain why Shiftpod has recently started giving away free “blast shields” or radiant barriers to go on top of the Shiftpods.
I decided to test this theory, so I added another phase to the experiment to compare the difference in temperature inside the tents from floor to ceiling. Here is what I found;
As you can see, the temperature between the floor and ceiling in the Blueshift stays almost the same throughout the day. In contrast, we see the heat being trapped inside the Shiftpod. The temperature difference between the floor and ceiling of the Shiftpod varies by as much as ten degrees in the hours leading up to one-hundred degrees. This is very interesting information because if we are able to deal with that trapped heat, we could potentially see benefits from the Shiftpod’s insulation. This will be addressed in an upcoming phase (Phase 4) of the experiment.
In Naked Sun, the Blueshift is the clear winner for morning temperatures. This is the time and setting where the Shiftpod is supposed to shine. Instead we see it falling behind its much cheaper cousin.
Phase 2: Loose Aluminet
Aluminet is a very interesting material which has found wide adoption among burners, just like Shiftpods. It’s both a radiant barrier and wind-permeable. This solves several interesting problems.
The idea of a radiant barrier is that heat and light will be reflected rather than absorbed, as would be the case with a tarp. The problem with past radiant barriers is that they were solid like a tarp, and with high winds, they become a sail that tries very hard to blow away. Many radiant barrier materials such as mylar are very delicate and will tear themselves to shreds with even the slightest wind.
Aluminet is made of a similar material to mylar, but it is reinforced and braided, so it forms a very strong barrier in the wind, which wind can actually pass through. It comes a wide range of opacities which allow different amounts of light through. I go with 80% Aluminet.
As I mentioned before, Shiftpod has recently started giving out free radiant barriers called “blast shields” which are basically just a non-breathable mylar -like material. The blast shield is basically a cheap and inferior alternative to Aluminet, and the fact that they are now giving them away for free seems to indicate that the makers of Shiftpod are aware of a potential design flaw in this very expensive tent.
Thermodynamics sometimes has a problem with both mylar and Aluminet, especially when they get dusty. Sure radiant barriers will reflect much of the light and heat, but dust will not. If the dust is touching the radiant barrier, then it doesn’t stop the heat from the dust conducting through the barrier and into the tent. Aluminet and mylar are not conductive barriers, only radiant barriers. This means that a dusty piece of Aluminet or mylar will conduct some heat through to anything they are physically touching. For this reason, if the radiant barrier is touching the tent, and it’s dusty, then it will not block as much heat as it would if it were several feet away from the tent, suspended from another structure. This will be expanded on in a future phase of the experiment.
This photo was taken in the afternoon. As you can see, the Aluminet is hanging from the two tents and tied to the fences. For the purposes of this experiment, the Aluminet is covering the east sides of the tents. This means it will block morning sun, and to a lesser degree the noon sun. The south and west sides of the tents are not covered. (This entire experiment focuses on the morning time.)
The addition of Aluminet pulls the curves closer together, and we see the Shiftpod performing much better after an initial heating-up period. But the thickly insulated Shiftpod is still much warmer than the thin and breathable Blueshift. The Shiftpod has two humps when the sun is hitting it straight on, first thing in the morning and then again at mid-day. Between these times, the sun is hitting its edges at an angle. This seems to impact the heat absorption as shown above.
Once we pass noon, the Shiftpod’s thickly insulated roof absorbs the conducted heat from the loose Aluminet, and traps that heat inside the tent. In contrast, the Blueshift’s breathable and un-insulated roof lets the heat escape. Right at noon, we see the Shiftpod suddenly jumps to nearly twenty degrees warmer than the Blueshift. This could be the problem that the makers of Shiftpod were trying to solve by giving everyone free blast shields to block the mid-day sun from cooking their thickly insulated roofs. By comparing the first and second phase data, we see that adding a radiant barrier op top of the Shiftpod does mitigate this problem to a certain extent, but not completely. Eventually the heat gets through since the barrier is touching the roof.
Phase 3: Passive Thermal Mass Batteries
Water as a molecule has a lot of interesting properties. One of these properties is that it’s really good at storing heat energy. In fact, my understanding is that no known material has a higher density of heat storage than water.
This gave me the idea of placing lots of water inside the tent to store and release heat. This would theoretically have the effect of flattening out the temperature curves so that they are closer to the average value throughout the day. I decided to use four five-gallon buckets of water as my passive thermal mass battery. These buckets would be easy to transport and store, and even use as storage for other gear. You could also fill one or two of those large 27 gallon totes and use that as your battery, but that seems like overkill and it would be a lot of water.
As you can see in the photo below, I also put one of my temperature probes into one of the buckets to monitor the temperature of the water so we will see that in the graph.
In order to accurately compare the performance of the two tents, I decided to split this phase into three parts and compare each tent’s performance against the other, then both together. Therefore Phase 3A will test the performance of the Shiftpod with a 20 gallon passive thermal mass battery. During this phase, the Blueshift will just be normal and without any thermal mass battery. Then during Phase 3B, they will be switched. The thermal mass battery will be placed in the Blueshift, and the Shiftpod will just be normal. Then we can compare the performance of each with the addition of the batteries. Lastly, during Phase 3C, both tents will contain the same thermal mass batteries.
In order to get the most accurate data, I let the tents and their thermal mass batteries sit for a full 24 hours before collecting the data as shown. This way we can see the data once the batteries have been well adjusted to the conditions we are observing.
Phase 3A: Shiftpod Only
I was a little surprised by this data. In the first graph above, we see that the thermal mass battery starts absorbing a great deal of heat long before we see a significant change in air temperature inside the Shiftpod. To really see the impact, compare the difference chart to previous phases of the experiment. Only in the pre-dawn hours does the Blueshift take the lead. I am amazed. With the simple addition of a passive thermal mass battery, the Shiftpod now performs better than the Blueshift all throughout the day.
Phase 3B: Blueshift Only
Now let’s look at the next part of the experiment, where the passive thermal mass battery is placed only in the Blueshift and the Shiftpod is just normal without any help from the batteries.
We see that the difference curve swings the other way. This is not surprising since the Blueshift is not insulated. I think this test should be compared to the first test in the experiment since that’s the same conditions the Shiftpod is under during this test. In the first test, both tents eventually reached essentially the same temperature, and the Shiftpod was slightly warmer for most of the day. In this test,we see that both tents follow very similar curves, but that for most of the day, the Blueshift is a good 10-12 degrees cooler than the more expensive Shiftpod.
It’s interesting to note that we don’t see precisely the same effect from the previous test (3A) where the thermal mass battery absorbs the heat that would otherwise constitute the curve of it’s surrounding tent. Instead we see a gradual warming throughout the day, and a reduced warming in the surrounding tent.
Phase 3C: Both Together
During this phase of the experiment, we saw that thermal mass batteries significantly improved the effectiveness of the Shiftpod, while not significantly improving the effectiveness of the Blueshift. Four buckets of water has a footprint of just a few square feet. You would barely notice these in the tent, and they seem to provide an enormous benefit. Probably you would see similar effects from filling an empty tote with water. This would be an interesting topic for a future experiment.
Phase 4: Active Thermal Mass Battery
In order to increase the efficacy of the thermal mass battery, it seems logical to test adding a fan, pump, and heat sink. This would mean you would need to supply constant power to it, but if it provides enough of a benefit, then this may be worthwhile. I removed three of the buckets for this phase of the experiment, using only five gallons of water in a single bucket. Expanding on this may prove worthwhile but at this point, connecting buckets would be complex. If we wanted to do a larger active battery, then probably a larger container would be more appropriate. This would also allow you to add ice to your container, etc in order to cool the tent even more.
Hanging this from the ceiling also has the added benefit of potentially mitigating that pesky heat-trapping effect in the Shiftpod.
Pictured above are a 240mm heat sink with two c. I hung the heat sink and fans from the roof of the Shiftpod and put the pump and hose into the bucket. Here is what it looked like in the early evening. (You can see the sun reaching behind the Aluminet to hit the Shiftpod from the afternoon side. This time of day is not part of the experiment.)
Here is the data on the active thermal mass battery in the Shiftpod only;
As you can see, the smaller thermal mass battery just isn’t able to keep up. Being active seems to make little difference in terms of absorbing the heat in the tent. This is an unexpected result; very interesting data.
Because we see such a limited effect even with the insulated Shiftpod, and because the larger thermal mass battery had essentially no effect on the Blueshift, it does not seem worthwhile to test an active thermal mass battery in the Blueshift.
Phase 5: Ventilation
As you can see in previous experiments, the temperature inside the tent can be as much as twenty degrees hotter than the outside temperature for much of the day. This suggests a simple solution; ventilation. This can be a problem in dusty environments at Burning Man. In other environments, this may be a better option.
Ventilation & Dust mitigation
I did some experimentation this year at the burn based on Nikola Tesla’s patents for solid state check valves as well as the closely related concept of vortex filtration. The basic principle is that when you have a fluid such as the air, and there is something in suspension, such as the dust, you can encourage the dust to fall out of suspension by forcing the fluid to suddenly change directions.
My idea was to take a section of about eight or ten feet of aluminum duct and hang it so that at least a few feet were hanging loosely and free to flap around in the wind. The other end of the duct would go into the tent, where a powerful fan would suck air into the tent. I set up some other ducts (pic) to maintain constant slightly-negative pressure and pull the hot air out from the top of the tent. This meant that no dust would blow in through these other ducts. The theory was that because the outside piece of duct was free to flap around, the open end would never be facing into the wind. This means that when air is sucked into the duct and drawn into the tent, that air would have to change direction 180 degrees in order to get into the duct. This means the dust would fall out of that air. As far as I can tell, this worked perfectly. I would definitely recommend trying this at the burn.
Phase 5a: Ventilation (Shiftpod Only)
The basic idea is pretty simple. We will have a fan drawing the air out of the top of the tent at 200CFM 24/7. Then an open vent will allow fresh air to enter the tent. This means all the air in the tent will be replaced every five minutes. This is generally considered to be the ideal ratio for ventilation, especially with evaporative cooling as we will see in the next experiment.
As you can see above in the photo, I have used the same hose from the previous experiment as well as the same 200CFM fan. The direction of the airflow is out of the tent. You can see the duct drawing the hot air from the roof area of the Shiftpod and then pushing it outside the tent. A window is open to allow fresh air to enter the tent, replacing the hot air being pushed out. This photo is for simplicity’s sake, but having the open window be close to the exhaust duct doesn’t make sense. In the actual experiment, only the window opposite the exhaust duct was left open.
As you can see, just like the passive thermal mass batteries in Phase 3A, ventilation swings the difference curve in the direction of the Shiftpod. Also just like Phase 3A, this puts the Shiftpod ahead by about ten degrees. Recall that with no assistance, the Shiftpod is a few degrees warmer than the Blueshift. Knowing that these two methods each impart a ten degree advantage plus the unaided difference, we will likely see large advantages when we pair these methods together in a later trial.
Phase 5B (Blueshift Only)
This is the same experiment with a 200CFM fan drawing the air from the center of the ceiling of the Blueshift and blowing it outside while fresh air comes in from another vent.
Here you can see the same fan and ducts going out through a window which is covered with cardboard for this experiment. Let’s see the data…
As you can see, adding ventilation did make the Blueshift cooler than the Shiftpod, but only by a few degrees. I was surprised to see how little impact was measured in phase 5 of the experiment.
Phase 6: Hung Aluminet
From the beginning, I suspected this would be the most impactful phase of the experiment. The idea here is that the Aluminet is suspended a few feet away from the tents in order to eliminate any potential heat conduction between the radiant barrier and the tents. This seems like the most logical step to take in order to see a really dramatic change. This is where the Aluminet will really shine.
Flat top shade structures are expensive! But they don’t need to be. Check out this post about how I cut the cost in half and eliminated most of the hardware involved while still getting all the benefits of a normal flat top shade structure.
As you can see, this material has a big impact versus the previous phase. The Shiftpod never hits one-hundred (as an average of its floor/ceiling temperature), though the temperature at the ceiling briefly does. The radiant barrier on the Shiftpod seems to really shine in this phase, with the highest temperature difference between Blueshift and Shiftpod we’ve seen so far.
Phase 7: Evaporative Cooling
Evaporative cooling (AKA swamp coolers) add humidity to the air in order to reduce its temperature. This works best in dry climates. The maximum temperature difference is a function of the dew point under the given conditions. This means the best case is a 40 degree temperature difference if there is 0% humidity, and less of an effect with higher humidity, with no effect at 100% humidity.
For this phase, I used the evaporative coolers I designed in this post. In both cases, the coolers burned about three gallons of water during the period shown.
Phase 7A: Shiftpod Only
Based on comparison of the data from Phase 6 to Phase 7A, there does not appear to be any significant temperature difference in the Shiftpod with the addition of the evaporative cooler. On the day the data was collected, humidity was 68%. This is probably why there was no significant temperature difference. Despite that, the evaporative cooler did burn through three gallons of water during this period, so it was working and cooling the Shiftpod despite the unimpressive results.
These values would likely be different if there was a significantly lower humidity. This was a problem at the burn this year, where the humidity was uncharacteristically high, and evaporative coolers were not working very well.
Phase 7B: Blueshift Only
As I suspected, evaporative cooling was basically useless in the Blueshift as well. This matches my experience from on-playa this year. By the end of build week, I threw my swamp coolers in my camp’s dumpster.
Phase 8: All Or Nothing
In this final phase of the experiment, each tent will take a turn with all or nothing. Based on comparing the results of Phases 5 and 7, there is no reason to include useless evaporative cooling in this phase. Instead, the more compelling phase 5 results will be included and simple ventilation will take the place of evaporative cooling. The more I think about it, the more sense this makes. If it’s twenty or more degrees cooler outside than inside, then simple ventilation is guaranteed to accomplish that or something close to it. This also parallels my playa experience, where ventilation is often the best and easiest option.
Phase 8A: Shiftpod Only
For this phase, the Shiftpod will be under hung Aluminet with the 20 gallon passive thermal mass batteries, and ventilation. The Blueshift will have none of these things, and be sitting out under direct sun.
Here we see the effectiveness of the ventilation system sucking the hot air out from the top of the inside of the Shiftpod. For much of the day, the ceiling is actually cooler than the floor.
Phase 8B: Blueshift Only
For this phase, the Blueshift will be under hung Aluminet with the 20 gallon passive thermal mass batteries, and ventilation. The Shiftpod will have none of these things, and be sitting out under direct sun.
As with several previous phases, there seems to be a critical tipping point when the Shiftpod suddenly becomes much warmer. My going theory is that it is related to the angle of incidence of the sun. I found the results of this last phase very surprising. I would have expected the difference curve to be much flatter and to stay below zero all day.
In the naked sun or with loosely draped Aluminet, it’s actually hotter than the cheaper Blueshift. Both tents perform a lot better under a shade structure.
Simple ventilation is more effective and comfortable and less complicated than evaporative cooling.
The Shiftpod is over ten times the cost of the Blueshift. Does it perform ten times better? No. In general, the tents perform pretty similarly. The Shiftpod excels in a few situations with some help. If I was choosing a new tent today, I would pay more attention to getting a good shade structure than to getting any certain kind of tent.
I was in need of high-precision multi-zone temperature logging gear for a chemistry honors project, and I found nothing online that would work well for my purpose, so I decided to put my CSCI46 skills to use and build my own.
I started with aNodeMCUwhich is basically a fancier but somehow also cheaper Arduino alternative which has wifi built-in. It works just like Arduino and you use the same Arduino IDE to program it.
So one really cool thing about these temperature probes is that they work with the OneWire library. This means you could use hundreds of these probes and they would share only a single I/O pin on the Arduino. My implementation uses five, but you could easily use many more if you wanted to.
Each temperature probe has three wires coming out; red, yellow, and black. Start by trimming the colored portions a bit so that there is around a centimeter of wire exposed. Then zip tie the probes together as shown, so that they won’t pull apart when in use. Next, twist each color together as shown. I used like-colored jumper wires to create clean and simple pins to plug into the Arduino, but however you want to accomplish that is fine;
The next step is to incorporate the pull-up resistor. This needs to go between the red and yellow wires. I added extra zip ties just to be safe.
Lastly, simply tape all of that up so it doesn’t come apart. My final product looked like this;
Simply add your wifi ssid and password, and the code should work as-is. It will output the IP address it has gotten from the router to the Arduino console. A best practice is to simply set this as a static IP on your router. Then, it will not change, and you will always be able to find the device.
Navigating to the URL of the device’s IP will present a comma-delimited, quotation encapsulated set of values for each sensor. There is no way to tell which sensor is which based on the hardware. The sensors have a built-in serial number, and the OneWire library knows which sensor is which. The list served at the URL will always show the values in the same order on that basis.
So we simply need to determine which sensor corresponds to which value. You will need to observe the sensor data and then place a warm hand on each sensor, noting which value changes temperature. I used tape and a sharpie to label each cord (1,2,3,4,5) so I would know which sensor corresponded to each value in the list the device serves at its URL.
Lastly, I wrote a cron script which runs on my Synology NAS and fetches the values from the device every minute, and writes them to a CSV file. This means that I can later look back and simply import the values into an excel spreadsheet.
Shade structures are perhaps the most important and powerful way of improving temperature conditions in a tent on playa or elsewhere. The value of a shade structure to someone who is trying to sleep can not be overstated.
The Traditional Way
A lot of people buy and build complex and expensive shade structures. Typically these are made using five-way joints with feet and ten foot sections of one inch emt conduit (or here). These are typically covered with tarps and ratcheted down.
At the burn this year, my friend Giorgio suggested putting up a flat top using rebar instead of feet and aluminet instead of tarp. This would mean far fewer parts, no need to ratchet strap it down since it won’t catch wind, and much easier to transport. I used paracord to tie down the aluminet which worked perfectly.
I simply pounded rebar into the ground, leaving about a foot above ground. I tied paracord to the eye bolt and dropped it through the aluminet’s grommet and then into the end of the emt conduit. This is fine since the cord is not bearing any load. It’s basically just there to keep the eye bolt from falling out if the aluminet flaps a bit. The wind blows straight through the aluminet so the force on the paracord is minimal. The other end of the conduit goes onto the rebar. The paracord is tied off on some lag bolts (This is overkill. There is probably a more elegant and less complex solution here). Below is a picture of this set up in my back yard as part of my chem honors project.
Wow so this design is less than half the price of the traditional model and comes with far less to haul in to camp. I will definitely use this design from now on! Here’s what it looks like in my back yard…