Build your own open source hardware Nest-style smart thermostat


With Arduinos or equivalent and low-cost sensors you can easily build something like this yourself. Open Hardware makes the hardware part pretty easy.

What makes Nest really cool is the thought and testing they’ve put into design, which is what differentiates a really smart thermostat from one that’s not much smarter than a clunky programmable-by-day-and-time thermostat that you have to haggle with any time you want to do something different. You’ll find that takes longer to do, even with open source software. (I haven’t yet been bit by the Nest bug, and keep a sufficiently irregular schedule I’m not convinced it’ll work well for me, but on the other hand, it’d be interesting to tinker with an open version.)

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I just don’t find pushing a button twice a day to be all that onerous.

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Yeah, me either. I really didn’t understand the desire to redesign the thermostat in the first place, nor Google’s purchase. [shrugs]

coule we combine this with the nixie clock? because a nixie thermostat would be pretty awesome.

Using $5,000 worth of equipment and $79 in parts it takes only a couple of days to make an imitation of a device that I can buy at Home Depot for $250 or the electricity company will sell me for $150. Success!

I have three nest devices. What I want is for Google to open up the interfaces and document them so that I can program them myself. The Nest software is not up to controlling a system that has two A/C units and three furnaces with overlapping zones. And it only uses input from the sensors in the thermostats. I want the system to come on automatically when one of us starts off for home.

It is a lot harder to push those buttons when you are not in the house. The nest saves me about $1000 a year in heating and A/C costs by minimizing use. It is also in theory capable of accepting load shedding requests from National Grid. So rather than build more power stations, they cap peak load by only turning on as many A/C units as they can cope with. I don’t really care exactly when my A/C comes on, what I care about is that it keeps the house acceptably cool.

What people could do to save energy is not the same as what they do. While you could turn down your thermostat every time you leave the house, I bet you don’t and neither will 99% of people. In fact I don’t think I want to meet the sort of person who diligently turns down the heat like that.

Does this DIY system also update my comings and goings to Google? Because I’m not comfortable unless I’ve surrendered every last shred of info about myself to the do-no-harm people.

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This makes not a lot of sense sense. Once it knows when you are likely to to come back, it can starting heating up in advance.

And I bet you 20 € that your comings and goings are quite predictable once a month of data has come in.

Okay, next target then - will someone please, please, please make this become real?

The content aside, I love the blog’s subtle use of short looping videos instead of photos. Maybe I’ll get bored of it in two years when everyone’s doing it, but it looks quite beautiful to me.

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You forgot the cost of the vehicle used (I drive a Silver Ghost–doesn’t everyone?–so that’s $200 million), the clothes to wear when on the purchase mission (I’m partial to the <a href=>Windowpane Plaid for such non-essential missions such as this, so that’s another $3K), another thousand for the cashmere overalls (with Hermes scarf cause it’s winter, you know), and also the education I had to pay for (spitballing here, let’s call it $300K, shall we?). I won’t bother with the cost of the roads, traffic systems, distribution systems (for the parts, yeah?), and so on, but golly gee that nifty thermostat is getting pricey, huh?

The stuff you mention is irrelevant and unnecessary to make the device. The laser cutter and CNC mill are not.

I have access to them at a local maker space, but that costs $100/mo and in any case the laser cutter is still down after someone mashed it.

Without those tools, the project is a lot more involved and costly.

HVAC controls have come a long way in the last few years, a “smart” consumer-grade thermostat merely being the most visible link in the feedback loop.

Even greater savings can be had through the use of outdoor temperature sensors, outdoor resets and indoor temperature sensors. Modern control systems can do a lot more than just make a better guess at when you need heating and cooling, they can actually make the heating and cooling process itself more efficient using equipment already in place. Before you drop fractional kilobucks on cutesy wall-hanging-app-machines, consider talking to an HVAC specialist.

Also, in many, many homes insulation continues to be the best bang-for-you-buck as regards energy budget savings, but it doesn’t give you quite as much to chat about at your next cocktail party.

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You’re a smart person so certainly you could work your way around those issues, and if you’re not, someone at the maker space could be that bulwark. Also, you’ve got a house with two A/C units and three furnaces, so the $100/mo (or, I would guess, the $50/2wks, or the box of donuts for one day) shouldn’t break your bank. As for the project becoming “involved”, well, that’s kinda the point of being a maker, isn’t it?
So, to recap, the problems you mention are irrelevant and unnecessary given some planning.

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If only there was a way to cut plexiglass without a laser… I’ve used jigsaws, scrollsaws, routers, hand-saws e.g. jeweler’s/fret saw. You will need a bit more plexi to play with and a bit more time, but the results should be just as good.

There are probably numerous off the shelf items that could be re-purposed as a housing. The first thing that popped into my head was a little bamboo steamer box, since it should be relatively easy to remove the woven stuff and replace with plexi:

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Let me introduce you to my wife… She will regale you with The
Tale of the New Roof Insulation

I’m pretty sure there’s a way to cut a ring of wood that doesn’t require a CNC machine. I’m actually surprised that this project didn’t feature some 3D printing somewhere.

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