building a DIY bed cooling contraption and saving the world. a manifesto in production.
Did you know the US uses more electricity on cooling alone than Africa does in total? Cooling uses about 10% of the world's electricity and / because it's generally wildly inefficient.
Did you also know that there's a robust link between temperature and sleep quality? https://advances.sciencemag.org/content/3/5/e1601555
This will only get worse globally as the world continues to climb in temperature, and using ever more coal-fired electricity to solve the problem with more A/C creates a feedback loop of worsening conditions, not to mention expenses.
So let's fix that.
Cooling the air, especially with modern "open floorplan" houses, is a huge volume. Big amounts of electrical energy go into sucking the heat energy out of a space, and out of the objects and humans therein. Then, because of our over-use of windows, solar gain heats the space back up again immediately anyway. We're fighting our architecture, but that's a story for another time.
Physics holds a few types of thermal transfer. The hero of our story is conduction - physically touching an object and transfering warmth - as opposed to convection: the energy moving around via the air.
Air is an insulator, and the thermal transfer ability of it against your skin is much lower than conducting, so cooling it as a means to cool your body is actually a pretty weak idea. The reason we chose it was convenience: you walk around your office and the whole place is held at a nice(r) temperature without you having to touch anything constantly. But it's not in itself very efficient.
There's a reason in cars we prefer heated seats and steering wheels: electricity warms them faster than the engine takes to warm up in the beginning but it also feels warmer. Touching a warm seat and holding that warmth even with cooler cabin air feels better than having the fans on hot with a cold leather seat. Conduction is more efficient, and it puts the energy where you actually need it.
Likewise with cooling, and especially with beds: when you lay down you're heating the mattress under you and that energy has no where to go - even with "cooling" mattress toppers, eventually they soak up all the energy they can hold and in 15 minutes they're just as warm as any other foam layer would be. The issue isn't the material, the issue is that the heat has no where to go.
And then you crank up the A/C in an attempt to cool the room itself down, but the mattress is still hot because it's under you where the air isn't reaching anyway.
Personally, I also like to sleep with blankets rather than without, but that's preference.
So we know where the energy is, and we know that cooling the air is inefficient as a process and ineffective as a means to actually having a good sleep.
Let's cool the bed.
- a 10,000 BTU A/C unit like you find at Home Depot is about 1220 watts to run. Mine takes less than 10 watts. It's literally a single LED lightbulb level of energy. You could bring it camping. You could run it on those little portable solar panels in the middle of nowhere. Outfit an African village.
- the A/C unit is incredibly loud and annoying, like running a lawnmower in your bedroom. Mine is completely inaudible (and I'm very sensitive to these things). I've found that I can run it without any fans at all with a sufficiently large radiator, so the only moving part is the pump (and it's very quiet + mechanically isolated in multiple places).
- the A/C unit weighs 71 lbs. and takes up the size of a small fridge. They're a pain to move and require a window to vent, so they're limited in where they can be placed in the room. Mine is the size of a shoebox and weighs a mere few pounds. The heaviest part is the 4L jug of distilled water.
- a similar A/C unit is $300-500, mine is roughly the same for now, but I suspect we can design improvements there and if manufactured at scale, immense design gains to be made. It's physically much much simpler with few moving parts.
- as mentioned above, the A/C unit actually does very little for sleep comfort itself. So now you have this loud, annoying, energy-sucking thing you're paying on your power bill for and the world is paying on it's nature bill for, for nothing.
So if you're in direct contact with a cooling mat, and that fluid is constantly being pumped away, you get a very efficient transfer of energy away from exactly the place you need it gone from.
You can sleep under the blankets, sleep better overall, use much less electricity which then requires a much smaller unit that makes far less noise, it's a win-win-win.
Save yourself. Sleep Better. Save the planet.
Yes, they've been invented, this is how I started along this whole path. I bought one.
I love the idea, as you can read I'm increasingly invested in this whole thing as the future of society and sleeping.
The Chili products, no offense, but they're the very first caveman attempt at this sort of thing. I wanted to build my own in an attempt to fix all the parts I didn't like about the existing offerings, and I reckon I could do it cheaper.
I think they're too loud by using cheaper fans / pumps / components. Mine has an electrical whine that sounds like a broken power supply that, while not a high decibel rating, is a frequency I just can't stand.
They're also pretty dumb, the logic of the UI is from the late 90's and I think we do a disservice to ourselves and our sleep patterns to not have curves and graphs of temperature over the night rather than setting it like a thermostat in a house (precisely because the conduction is so much more effective, it can also be too aggressive when set wrong).
There's also Eight Sleep which are way upscale - the unit with the pad is almost $2k and the mattress is even more. And that's fine, they're basically the only players in the market and aim to be a premium product, great. But also, the margins here have to be huge. The cost of physical goods is a couple hundred bucks. They have an app, which is a step in the right direction, but I'm told it's not very good. I dunno. I've never tried it myself.
I think there's a place for the middle class. The $300-500 Home Depot bed cooler. The hardware isn't that expensive, the electricity use is TINY, it can be dead silent and much smaller than a portable A/C unit and still more effective at actual body temp control. Sure seems like a win-win-win.
So yes they exist, but it doesn't seem like anyone is aiming for this mass market. I personally think there should be one in every bed, at every price point, for every human. It seems so feasible to do.