Ask Hackaday: What’s The Best Way To Heat A Tent With A Laptop?

For Europeans, August is usually a month of blistering heatwaves, day after day of cloudless skies and burning sun that ripens fruit and turns we locals a variety of shades of pink. Hacker camps during this month are lazy days of cool projects and hot nights of lasers, Club-Mate, and techno music, with tents being warm enough under the night sky to dispense with a sleeping bag altogether.

Sometimes though, the whims of the global weather patterns smile less upon us hackers, and our balmy summer break becomes a little more frigid. At BornHack 2021 for example we packed for a heatwave and were met with a Denmark under the grip of the Northern air mass. How’s a hacker to keep warm?

The Cold, Cold World Of The Globe-Trotting Hackaday Writer

Folding@home makes for a 31W heater.
Folding@home makes for a 31W heater.

Still warm enough in the low 20s Celsius during the day, but dropping down much lower at night which for someone equipped only with a thin summer sleeping bag is a bit chilly. Picking up an electric heater for a few kronor in a nearby town is a sure-fire way to become very unpopular with the power team at a small event, so what was left? The answer, and the catalyst for an entertaining discussion in our village, was to run a computationally intensive task on a laptop to generate enough heat for a comfortable night. For me that meant Folding@home processing a few medical research work units for the Hackaday team’s points total, but despite having a cozy night as a result had I hit upon the optimum solution for computational heating? This is where your opinions come in, so share them in the comments below.

How Can I Get More Than 31W Out Of An Old Dell?

My Hackaday articles are either cranked out on an Asus Chromebook or a 2017-vintage Dell Intel i7 laptop. The Asus isn’t up to much in the heat stakes because it’s designed as a low-power machine with a frugal battery life, but the Dell by comparison is capable of spinning up its fan at the slightest notice. Aside from its four processor cores it has a spinning-rust disk drive that can get nice and toasty, a DVD drive that must be good for a bit of heat, and a nice big LCD that sadly I wasn’t using for heat-making because I needed to sleep. So with Folding@home I was not really using the laptop’s full potential because I was only lighting up the CPU. At idle it used 10W, which Folding@home could push up to 31W. Could I find an algorithm or a piece of software that might push it closer to the limit? Perhaps I could mine a cryptocurrency, maybe farm Chia to warm up that disk drive instead of Folding@home, but it’s worth pointing out that a 2017 Dell with an Intel chipset isn’t going to make me a millionaire.

All this opens up another discussion, is what I’m doing wasting the computing power or not? Folding@home leaves me with a cosy feeling inside for supporting medical research, yet here I am worrying about the ethical footprint of crypto mining for heat in my tent. Given that an electric blower heater generates no benefit at all other than the heat it creates, perhaps I should concentrate on the heat.

So all this tent-heating fun provides an amusing diversion for Hackaday readers just as it did for a group of mildly chilly hackers over breakfast in a Danish field. How would you get the most heat from your laptop? Distributed computing, crypto, or some other specialised algorithm? Or maybe I approached the problem from entirely the wrong direction and perhaps I should have cooked up something mightily inefficient in the amateur radio department. It’s over to you!

49 thoughts on “Ask Hackaday: What’s The Best Way To Heat A Tent With A Laptop?

    1. Other methods of warming up a tent:

      One tea candle is worth about 30-40 Watts if you want to risk the fire. Practically speaking, you need many.

      A 70 Watt soldering iron. Plausible deniability! “I was fixing the radio.”

      A charged up car battery is worth at least 500 Watt-hours. A standard headlight lamp will provide the heat.

      10 liters of boiling hot water gives off approximately a kilowatt-hour of heat. A jerrycan full of hot water, wrapped in a blanket, will stay hot overnight and keep giving off couple hundred watts on average.

      The main problem is that anything below a hundred watts is more or less placebo, because your standard polyester camping tent doesn’t hold any heat.

      1. While I entirely agree most tents are terribly (if at all) insulated you have to account for volume too – some tents are really tiny, and in those just not letting the outside air mix with it directly will create a bigger temperature differential than the poor insulation would suggest (of course being smaller they also have less surface area to loose heat through, a smaller volume of air to heat in the first place etc).

    1. True, true. We’ve been camping a lot and sometimes you just have a bad day and your body doesn’t want to warm up. What then helps is a short but intense “mini-workout”. Just to get your heart-rate up and your fingers/feet warm.
      Jumping jacks for example. Works wonders even in serious cold.

  1. The combustion energy of burning lithium batteries is actually a lot less than an equivalent weight of gasoline. And, a couple kilos of gasoline is a lot cheaper than a laptop. Using laptops for heat may be a satisfying idea but I’ll stick with conventional fuels.

    1. Even better, on your camping trip there might be fuel scattered all around the campsite! You could gather that and produce heat with it.

      I know, it might be a bit unorthodox, but just think of the possibilities!

  2. For a few months before the TX power grid failure, I was running Folding@home on my older desktop with GTX 980 as well as any other computer in my home office. I figured the angry pixies should do some science on their way to warm my house.

  3. A friend of mine in the same situation reported some success with a number of concurrent “yes > /dev/null &” equal to the number of hardware threads the machine is capable of.

    There’s also cpuburn, a tool designed to make a CPU draw as much as possible, but it may not have been updated to work as effectively as possible on latest CPUs.

    But then, to really crank up the power you need to run at the same time something that stresses the GPU as well. Do somebody know a GPU stressing program?

  4. Tents are terribly insulated. Pulling a Mylar thermal blanket over the top as an extra layer would help or perhaps wedging it between the 2 layers. Maybe loads of spare bubble wrap? A tarp over the top of a tent a leaky tent (thanks to a cow’s horns) warmed it up – unfortunately it was summer.

    So to answer the question – if there’s only a small amount of heat available, make best use of the heat by stretching it out – hence insulation.

  5. Skip the laptop. Put some (dry!) rocks close to a fire to get them good and warm and put them at the foot of your sleeping bag. Baking potatoes will also work, and you can theoretically eat them later.

    Or if you’re determined, burn the laptop to warm the rocks. I wouldn’t eat any potatoes cooked that way though…

  6. I remember being at a lan party in someone’s uninsulated shed (not that we really build *anything* insulated in Australia, but I digress) and freezing overnight. No problem, just turned my tower around and blew all that nice warm air into my sleeping bag while I continued playing Trackmania…

  7. 1- Clothing iron sitting upright. Plus surf clothing iron cooking hacks.
    2- Electric water pot and stream. Humidity keeps Apt warmer. Surf for great hot drinks and soups.

    When I was a baby my mom stayed in a cold New York apartment with a broken window and broken heater. She made a tent with a blanket and used a clothing iron to keep me warm. She insulted my dad when she finally got in contact with him for renting such a place. Finally she packed up and moved to warm Puerto Rico.

  8. Look at the weather forecast at the beginning of the event and if the weather is cold you could ask the network team to place the switch for your field in your tent.
    Make sure your power lines are ok so the switch won’t turn off in the middle of the night course that will make your neighbours very angry :-)

  9. Provide proper insulation – both from ground and around yourself. That means layers.
    Heat can be “stored” – hot water jars or stones from fireplace – and slowly released under your sleeping bag or shelter (hot stones covered with thin layer of ground).
    Heat can be reflected – equip your first aid kit with space blanket or two.
    Heat your body not the surrounding.
    Read Mors Kochanski and watch his lectures. His view on shelters and understanding of survival gear was unmatched – just check his supershelter idea.

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