Multpurpose Apocalypse Sensors

The end seems pretty nigh, so why not measure it? This sensor array is ready whether it’s fires or nuclear war, chemical attack or nuclear winter.

This Sensor Array Measures:

    • Particulate Matter: PM2.5 is the international standard measure of air quality related to fires. It measures density of particulate matter with a size larger than 2.5 microns (Technically 2.5 microns is an average, and this metric generally refers to particles larger than 0.8 microns.).  This includes smoke but also includes pollen and some other pollutants.
    • Nuclear Radiation: I have always wanted to have a geiger counter, so I decided to buy two; one for inside and one for outside.
    • Smoke and Carbon Monoxide: Every year is the worst fire year ever.
    • Temperature and Humidity: Temperature and humidity play a huge role in the impact of particulate matter in the air on the respiratory system. Even without smoke, the wrong humidity levels can cause respiratory problems for sensitive people. Tracking this number will help us see the potential impact on air quality indoors and out.

As the latest worst-ever fire season gets started, I am planning to explore the effectiveness of several methods for indoor air filtration. I wanted to measure the results so I decided to expand on earlier work and build a series of high precision sensor arrays which can measure and compare smoke levels in the air.

Why not radiation too? These sensor arrays will become an ongoing source of interesting data as the world continues to fall apart. Watching the Chernobyl miniseries, I was struck by the fact that the scientists had a sort of “smoke alarm” for radiation in their offices. I asked myself why that isn’t something we all have. How would we know if there was some serious radiation danger? Well now I will know.  lol.

Additionally, I will be comparing the efficacy of house plants alone and together with air filters on improving indoor air quality during fires. This builds on earlier work by NASA which showed that in general, house plants have a major positive impact on indoor air quality, but smoke was not one of the things NASA tested for.

(Incomplete photo, just waiting on the geiger counters.)

Apocalypse Sensors

I also wanted to experiment with building a multisensor wifi array for the first time. I decided to do four sensors which will give a lot of relevant data.

The Sensors

DHT22 Sensor: Gives temperature and humidity with high precision. This is not directly relevant but it makes it a more complicated and interesting project. Also, I suspect that humidity in particular will have an impact on filter performance.

PM2.5 Sensor: This sensor measures particulate matter larger than 2.5 microns. This is the standard unit of measure for air quality related to fires. I also got some tiny fans to blow air through these sensors in order to maintain a good sample of the air quality on an ongoing basis.

Geiger Counter: This is self explanatory. The Geiger-Muller tube detects ionizing particles which intersect it. This gives us the cool radioactive clicking sound and lots of information about radioactivity in the air. Scientists have declared that radiation is the hallmark of the Holocene or the epoch of humanity. It always seems like some nuclear disaster is spreading and threatening the globe. Let’s measure it over time!

MQ-2 Sensor: Gives smoke and carbon monoxide in particles per million. This is more like a smoke detector sensor versus an air quality meter. I have no idea what we will see with this sensor. It will be interesting to start comparing the PPM data to the PM2.5 data.

The Microcontroller

Probably any microcontroller will work, but initially I decided to use the very cheap and simple NodeMCU which is just a few dollars. This has wifi and I already had a box full of them. I’ve used these in the past on other projects. While they work great with digital inputs, I was not able to get the analog input to work; also there is only one analog input and no analog outputs which is frustrating.

I changed my mind and decided to go with the new Arduino Mkr Wifi 1010 because it has so many analog pins which makes this project a lot easier. It’s a little more expensive but it has much better support in addition to those critical analog GPIO pins. It also has eight digital pins with six being PWM; a very versatile microcontroller. Allegedly it even has OTA so you don’t have to plug it in to flash new software. This will be great if the sensors are set up somewhere and I need to push an update without moving the array. The simple I2C interface means this microcontroller  can also run an lcd screen in addition to the sensors which means it will be easier to have verbose output on the data.

The Code

The microcontroller simply hosts a webpage as well as a json endpoint with all the data. It also has REST endpoints for each sensor so it’s very easy to query the sensors or to quickly view all the data on the homepage.

Here is the first draft of the final code. The DHT22, MQ-2, and PM2.5 sensors are implemented. Each sensor has an API endpoint so they can be polled individually, or there is a json endpoint to poll them all simultaneously. This version also includes the LCD display which cycles through displaying all the sensor values.

I still need to incorporate the geiger counters once they arrive.

If you’re going to use this on another microcontroller, you would probably just need to change the wifi parts or remove them. You could also simply log the data through USB.


Some of the PM2.5 math comes from work done on this post.

Some of the code for MQ-2 is based on this post.

The DHT code is based on the sample code from the Adafruit library in the Arduino IDE.

Preparing For The Worst Fire Season Ever

I have severe asthma. As such, fire season in California poses a real threat even without the additional risk of a respiratory pandemic. Many of the comorbidity factors from covid-19 are related to decreased breathing capacity. If you get pneumonia while also having an asthma attack, you’re gonna have a bad time. As such, I wanted to make sure to prepare early since all the N95 masks are already taken for coronavirus.

N95 masks are the ones that can filter smoke. Incidentally, they can also filter coronavirus. Therefore they are in extremely high demand by medical professionals who need them. I would not buy them for that reason. Also, I still have a dozen or so left over from burning man last year. (N95 also filters playa dust.) Sadly though I tried, I was not able to donate these because the box was opened.

I have spent several years together with friends exploring the best ways to filter the indoor air quality during fire season. According to NASA research, one of the best things you can do is to have the right kind of indoor plants. Unfortunately while this filters many harmful chemicals, in my experience it does not seem to be effective against smoke. Additionally, it’s slow. I have tried many different kinds of air filters, and landed on a very solid and excellent setup.


($10 ea) 20×20″ MERV 13 Filter

($20) 20″ Box Fan

$30 Total

Houses and Faces

An N95 mask is certified on a scale called NIOSH. N95 mask certification actually has nothing to do with viruses. It is a scale for filtering particulates which do not contain oil. Incidentally, that includes viruses as well as smoke. N95 masks are also certified for biocompatibility since they are touching the face. There are many other factors that go into the N95 mask certification.

NIOSH Ratings

For the purposes of this post, all that really matters is filtering smoke. So when we look for a house filter to fit the need, we don’t necessarily care if it’s ok to wear it on your face or how resistant it is to oils.

House filters are rated on a completely different scale called MERV. MERV 11 and up are rated for smoke. MERV 13 and up are also rated for viruses and bacteria as well. An average MERV 13 filter currently costs under $10.

MERV Ratings

There are any number of expensive air filter products you can buy which run up into the hundreds of dollars. I am going to show you how to accomplish the same quality air filtration for just $30.

One common size for MERV 13 filters is 20″ x 20″. This is the same size as the generic $20 box fans you can find at any department store from Walmart to Home Depot.

It’s a simple matter of using a few pieces of duct tape to attach the filter to the fan, and you have one of the highest quality air filters you can get for just $30.


For just $30, you have essentially the highest quality air filter possible which will last for years depending on your situation. In my case, one or two MERV 13 filters lasts me the full fire season.

Breathe easy!

The fact that housing is almost always only being built by investors means it’s not possible to have affordable housing for everyone.

CJ Trowbridge



Urban Studies GWAR Final

The fact that housing is almost always only being built by investors means it’s not possible to have affordable housing for everyone. In this paper I will show that when real estate investors act in their own rational self-interest, they harm everyone else. I will show that this is because affordable housing can’t be a good investment. As we will see, there are many non-profits struggling to develop and operate affordable housing, but there is not nearly enough funding available for them to meet the demand. Even before the current corona crisis, we were nowhere near on-track to meet our current housing needs. This problem has been getting worse for a long time; we used to have widespread public housing projects to fill unmet need. Finally, we will see how Crisis Theory explains the current crisis while also suggesting a solution.

Real estate investors who act in their own rational self-interest harm everyone else. Monopolistic practices prevent competition and artificially inflate prices because real estate investors collude to decrease supply. Height and bulk restrictions prevent housing from being built. Holding vacant property to deliberately drive up price. Delaying construction until prices go up. As a political and economic special interest class, real estate investors fight for interests that are exactly the opposite of the interests of the people. Adam Smith said as much in his book, The Wealth of Nations (Smith 43). Local governments are dominated by these special interest real estate investor groups. These groups work against the needs and interests of the broader population, purportedly in the public interest but actually only in the interest of the real estate investor class which they represent.

Affordable housing cannot currently be a good investment. The barriers and systems put in place to artificially inflate prices by preventing density from increasing and preventing new development makes it cost-prohibitive to build affordable housing (Hertz). By comparing income percentiles in every state to housing prices, my original research has shown that nowhere in the country is housing affordable, and in most states, it’s not affordable until you reach the 75th percentile in income. (Appendix 1) Efforts to incentivize for-profit investors to build at least some affordable units include trivially small “fines” in lieu of those units. The in-lieu fee in San Francisco is currently about $200 per square foot. Let’s consider an average apartment which in San Francisco is 747 square feet (Rent Cafe). This means an investor need only pay $150k in lieu of building an affordable unit. Building an affordable unit costs an average of $750k in San Francisco (Fuller). Now consider that the average market-rate rental price for that unit in San Francisco is $3,629 (Rent Cafe). This means that even at market rate, this unit does not break even for 17 years. At an affordable rate, it is not likely to ever break even at these prices. Therefore, for-profit real estate investment is focused on providing for the wealthy while increasing the prices paid, meanwhile the vast majority of people must go without any affordable housing options. This problem exists everywhere; San Francisco is easy to talk about because so much research has been done, but the same holds true in every state, as you can see in Appendix 1 where I compare these numbers across the country.

There are many non-profits developing and operating affordable housing, but there is not nearly enough funding to meet demand. Many of these focus on specific neighborhoods, for example the Tenderloin Neighborhood Development Corporation focuses protecting and developing affordable housing in the Tenderloin neighborhood while the Chinatown Community Development Center focuses on that neighborhood. Others focus on specific communities or causes. These include non-profit affordable housing for formerly unhoused people, people living with AIDS, seniors, and other groups. All of these nonprofits must compete for extremely tight funding. In the words of a development officer I interviewed at one of these organizations, the solutions they are able to build are not even a drop in the bucket towards solving the problem.

We used to have widespread public housing projects to fill unmet need. This gave us the ability to house everyone and provide enough supply to meet demand. During a period of extremely racist public policy, almost all public housing was demolished. 90% of that housing was never replaced, and this was almost forty years ago (Race, The Power of an Illusion).

Even before the current corona crisis, we were nowhere near on-track to meet our current needs. The San Francisco bay area’s official RHNA projections say some parts of the bay will not meet their 2016 housing needs until 2880 at the current pace (MTC). Housing is not affordable anywhere in the country unless it’s subsidized, and states are going bankrupt because of the current crisis. In a recent interview, California Governor Gavin Newsom said he expects unemployment to pass 25% in the coming weeks (Vanek-Smith). The broader global economy seems likely to suffer widespread collapse in the coming months and years. Housing will be hit hard, as more and more people fall from being unable to afford enough housing to being unable to afford any housing. We are likely to see a dramatic rise in homelessness and civil unrest.

Crisis Theory explains the current crisis while also suggesting a solution. The fundamental argument of Crisis Theory is that under capitalism, a moment inevitably comes when certain kinds of countervailing forces overpower the prevailing forces, causing a crisis. At this point, fundamental change is possible, or else we can face the long slog towards trying the same mistakes once again. In this case, one of the prevailing forces was the over-exploitation of housing. Instead of competing to provide enough housing to meet demand, players in the market colluded to eliminate housing while artificially inflating prices through anticompetitive oligopolistic practices as outlined above. The main countervailing force in this crisis could be seen as the under-exploitation of labor. 75% of Americans cannot afford housing despite having one or more jobs. This essay focuses on the housing issue, but similar issues affect labor in this country.

Because we have a crisis, we have the opportunity to create fundamental change. How do we do that? Affordable housing has become a condensing symbol in American culture. Everyone who hears the phrase understands the issue at least to some degree, if only through the personal experience of being one of the 75% of people who cannot afford housing. If we look at this issue through the lens of Kingdon’s Three Stream Model of policy change, this condensing symbol fulfils the requirements of the first stream; the troubling social condition has been clearly articulated with a condensing symbol and most people understand that there is a social problem around affordable housing (Kingdon). The second stream, policy, is also well developed; there is a clear policy framework in place for how to build affordable housing in the current set of conditions. Just look at the many nonprofits which are already doing that with the limited funding that’s available. The piece that’s missing is the politics around how much money needs to be spent on this issue by the government. Currently, the amount being invested is barely a drop in the bucket. All that’s required to solve this problem is for the streams to come together during the window of opportunity provided by this crisis and broaden the available funding to such a degree that enough housing can be built to make a meaningful impact on this issue. Hopefully at the same time, we can also address anticompetitive practices such as height and bulk restrictions which prevent new or denser housing from being built in many areas around the country.

Kingdon's Three Streams

We have spent over six trillion dollars on the “war on terror” (Zeballos-Roig). That’s a billion dollars A DAY for the last twenty years. How much different would our nation be today if we had spent that money on housing, education, healthcare, infrastructure, and small businesses? We’ve spent MORE than that in the last few weeks alone in response to coronavirus (Van Dam). A bill just passed the house to spend yet another three trillion on coronavirus (Shabad). The amount of money we spend on issues we take seriously is incredible, and yet we live in a country where 75% of people do not have access to housing they can afford. We have the tools, we have the organizations, we have the people in place, we understand the problem. Solving housing is not impossible, we just need the political will to accomplish the task. We face dark times, but we also have the rare opportunity to decide what kind of world we want to go back to when the global collapse is over. In conclusion, I believe that every community which can’t meet its housing needs should automatically get enough federally funded non-profit-administered high-density housing to fill all unmet housing needs.



Works Cited

Fuller, Thomas. “Why does it cost $750,000 to build affordable housing in San Francisco?” The New York Times. Published 2020-02-20. Accessed 2020-05-17.

Hertz, Daniel. City Observatory. “Housing can’t both be a good investment and be affordable.” Published 2018-10-30. Accessed 2020-05-17.

Kingdon, John. Agendas, Alternatives, and Public Policies. Boston: Little, Brown, 1984.

MTC. When Will Bay Area Cities Reach Plan Bay Area 2040 Housing Targets? Accessed 2020-02-11. plan-bay-area-2040-housing-targets

Race, The Power of an Illusion. California Newsreel.  April 2003.

Rent Cafe. “San Francisco Rental Market Trends.” Accessed 2020-05-17.

San Francisco Planning. “Inclusionary Affordable Housing Program.” Accessed 2020-05-17.

Shabad, Rebecca. “House passes Democrats’ $3T coronavirus ‘HEROES’ aid: Stimulus checks, money for states, rent assistance.” NBC News. Published 2020-05-15. Accessed 2020-05-17.

Smith, Adam, and Edwin Cannan. The Wealth of Nations. New York, N.Y: Bantam Classic, 2003.

Van Dam, Andrew. “The U.S. has thrown more than $6 trillion at the coronavirus crisis. That number could grow.” The Washington Post. Published 2020-04-15. Accessed 2020-05-17

Vanek-Smith, Stacey. “Gov. Newsom On Reopening California” The Indicator. NPR. Published 2020-05-07.

Zeballos-Roig, Joseph. “The US has blown past $6 trillion in ‘war on terror’ spending since 2001 — and its cost to taxpayers will keep climbing for decades, study says.” Business Insider. Published 2020-11-21. Accessed 2020-05-17.



Appendix 1

Summary: Affordable rent is defined as 30% of income. Comparing income percentiles in every state to median rents, you can see that for most states, up to 75% of the population can not afford rent. This data is from before the pandemic and spiking unemployment rates, so these problems are likely far worse now, but it will take years to understand exactly how bad things currently are.

Housing Affordatbility by percentile by state

What’s Coming

Things are about to get a lot worse. Once numbers start to appear about how many businesses will never reopen, then we will fall off the cliff.

Crisis Theory says a crisis happens when the countervailing forces overpower the prevailing forces; then there is potential for either fundamental change, or starting over and trying the same thing again. America is just one crisis after another, always escalating. This is perhaps the biggest one yet.

Things are about to get a lot worse. Once numbers start to appear about how many businesses will never reopen, then we will fall off the cliff.

We already had negative inflation combined with near-zero interest rates before the crisis started, which means even a competent government would have essentially has no power to solve or improve the situation.

Small businesses were already over-leveraged with variable rate debt, so raising interest rates would only speed up the collapse and make things worse. Most small businesses were borrowing at the maximum they could pay back because we were at the height of the market. This means as soon as there is a decrease in business, they fold.

California Governor Gavin Newsom says unemployment will hit 25% in the next few weeks which is higher than the peak of the great depression. This means people won’t have money to spend at small businesses, so small businesses will close. All of these dominos point towards long-term global collapse which will likely take a decade or more to climb out of.

We have spent a billion dollars a day for the last twenty years on “the war on terror,” or about six trillion total. Trump has spent that much in the last few weeks with the only goal being to push the collapse until after the election. The problem here is that instead of spending the money in smart ways that could minimize the damage, he is spending it on bailing out investors through QE. This means the investors will escape with their fortunes just in time for everyone else to lose everything, and with no money left to actually work on solving the problem.

It’s going to be very bad from every angle.

To connect these dominos back to my original point, one good example of a prevailing force is over-exploitation of housing and stocks. In the first case, 75% of Americans can not afford rent as shown below. In the second case, even though Tesla only made $4b this year, it’s stock price values it at $140b. This ratio is absolutely absurd except at peak market hysteria. Seeing ratios like this is a good sign that things are about to collapse.

The countervailing forces include wages which are so low that the vast majority of people could not afford rent even before the crisis. Here is some original research I did last week for an Urban Studies class comparing income to housing prices. As you can see, almost nowhere in America can the bottom 75% of people afford housing.

There comes a point when enough people can’t survive the system, and the system stops working. People may refuse to comply, or they may simply no longer be capable of complying. While there are many cases of rent strikes, Amazon strikes, and other workers and tenants refusing to comply with the system, I suggest that the latter case is almost upon us and likely to be far more significant.

Add to this the fact that hurricane season is starting early, and officials say this will be the worst fire season in history, just like last year was and the year before that. Notice I haven’t even mentioned the pandemic at all in any of my comments. 🤣 that’s just the seasoning on top of the dumpster fire we are in.


I originally made this argument two years ago. If Trump hadn’t done huge tax cuts for the wealthy, this crisis would have happened then. He pushed it back by several years, but it’s well past the point of no return now, and things are only going to get worse.

Raised Bed Gardens and Water Distribution

Given the many weeks of isolation in quarantine, I decided to move home rather than continue to pay  bay area prices to be in quarantine indefinitely. It was nice to spend time with family, and we decided to remodel the house to keep ourselves busy. My project was the new garden.

I decided to build three 4×8 raised beds. Pretty simple design. Each bed takes three 2x4s with one cut in half. Then screw the ends together. Staple barrier fabric across the bottom, and fill with dirt. Next, I bought 125ft of soaker hose and wound it through the gardens, held in place with garden staples. For the finishing touch, I added a small fence in front to keep the dog out, and solar garden lights in the beds.

Here’s what it looks like;

raised bed gardens complete


The soaker hose is not designed to carry enough pressure to run more than about 40 feet. So it would need to be split into a separate run for each bed. I also wanted to be careful not to let it drip in between the beds, otherwise the weeds and grass would take off and be hard to control. So I built this;

water distributor

Basically, there is an inlet at the bottom for a hose to attach. I had already run a 100ft hose all the way around the yard from the spigot to the gardens, so it just connects there.

Then the high pressure hose branches off into three valves to control the pressure to each bed separately. Then there is a corner to bend down to the soaker hose attachments. This prevents water from dripping outside the beds. Here’s what it looks like all put together;

all put togetherI also added an automatic timer at the spigot which turns the water on and off on a schedule. So now it’s just a matter of tuning the amount of water each bed receives with the valves!

Trellis Alternatives

I didn’t want to use those stupid tomato towers for all the plants so instead I got some eight foot posts and drove them about a foot into the ground, then I stapled chicken wire around them. This also keeps the cats out while providing something for the plants to climb. I plan to espalier both the tomatoes and cucumbers, as well as the zucchinis and sugar snap peas.

Garden fences

EDC: Queer Student in Oakland, CA

I have moved to Oakland, CA to focus on getting a degree in Urban Studies at SFSU as well as working on lots of exciting queer activism and housing activism. Here is my updated everyday carry.


I am trying different backpacks and I mostly hate them all. Currently I’m using the basic Jansport I toured Europe with.

Data: Are Shiftpods Actually Cooler?

Key Findings;

  • Shiftpods are not significantly better than cheap alternatives.
  • No tent performs well in direct sun.
  • No matter what kind of tent you have, putting it under a shade structure is the most important thing for keeping it cool inside during the day.
  • Evaporative “swamp” coolers are not as helpful as simple ventilation.
  • Thermal mass batteries are a simple and very effective tool for normalizing temperature throughout the day.

The Experiment

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.

Sensor Equipment

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.
Phase 1 Graphics
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;
Phase 1 Adendum
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.

Phase 2 Photo

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.)

Phase 2 Graphics

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

Phase 3A Photo

Phase 3A Graphics

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.

Phase 3B Graphics

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

Phase 3C Graphics

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.

Phase 4a Photo

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;

Phase 4A Graphics

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.

Phase 5A Photo

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.

Phase 5A Graphics

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.

Phase 5b Photo

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…

Phase 5B Graphics

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.

Phase 6 Graphics

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

Phase 7A Graphics

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

Phase 7B Graphics

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

Phase 8A

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.

Phase 8A Graphics

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.

Phase 8B Graphics

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.

Final Thoughts

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.

DIY High-Precision Multi-Zone Temperature Logger

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.

The Hardware

I started with a NodeMCU which 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.

I decided to use DS18b20 temperature probes which come in a waterproof five-pack with long cords. These also need a 4.7k ohm pull-up resistor which I will explain in a moment.

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.

Expose about 1 cm of wire

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;

Twist similar colored wires together

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.

Pull-up bridges yellow and red wires.

Lastly, simply tape all of that up so it doesn’t come apart. My final product looked like this;

Final Product

The Code

You will need to download and install the Arduino IDE, the Temperature Sensor Library, the OneWire Library, and the CH341SER USB Driver for the NodeMCU Arduino. Then go into the IDE and add the following URL in the preferences section as an “Additional Boards Manager URL…”

Next, take a look at my final code, here;

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.

The Data

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.

Cheap Flat-Top Shade Structure (Alternate Design)

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.

Traditional flat top shade structure

Parts List

10′ by 20′ Total Cost: $382.98

Another Approach

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.

Parts List

10′ by 20′ Total Cost: $158.29

Less Than Half The Price

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…

Shiftpod and Blueshift Under Aluminet

Psychedelic Glasses From Decomp ($10)

Burning Man Decompression was a blast this year. I wore a pair of psychedelic glasses which made everything look like this. A lot of people asked me for the link to them, so here it is!

They just look like normal glasses from the outside…

Psychedelic Glasses

Another person had this pair which were also popular so  decided to attach the link to them as well.

Another pair of psychedelic glasses