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> Depending on where you live you can save more money by simply using a good size fan blowing cold air into the house at night during the summer.

I have a whole-house fan (Western Massachusetts), and the "where you live" caveat is a biggie. It depends on sun exposure, air movement, humidity and local factors (like air flow through the home). We've found that running the fan at night keeps the house cool through mid-morning (on warm days with low humidity) but after that the house warms up very quickly and that's when the A/C is turned on.

I'm happy you had a good experience with a large fan but don't automatically assume that it's a proper solution for other applications.

All of these things can be automated. Since the Nest is connected via Wifi and Zigbee, a future firmware upgrade (or an external controller) could add support for a Zigbee-connected fan controller. If the outside temperature is in the direction of the target temperature, turn on the fan.

It sounds like you're in a desert-like area with wide temperature swings. The learning system when integrated with your zone system could figure out how cold you're willing to get at night to store cold air for the day, or even use unoccupied rooms to store very cold air to be released into the house throughout the day.

I agree that a thermostat alone isn't enough to save significant amounts of energy, but this does have the potential to get get some smart technology into more homes, where it can be expanded later to include everything you describe.

The "Nest" is simply the wrong approach. By itself it is nearly worthless (my not-so-humble opinion) for anyone but the most technologically incompetent thermostat users out there. And even then, you'd have to wonder. Where is the data on how many people can't or don't program their thermostats?

Now, some people might buy it just because it looks cool on the wall, and that's OK.

A real thermal management system for the home does not start with a high-design thermostat on the wall. You need multiple types of sensors in every room and multiple outdoor points.

You need to change the way airflow can be channeled around a home.

You might even need to change the paradigm and heat/cool objects that can provide thermal inertia (like the floor or walls) rather than just air.

You need to be able to selectively inject other heat sources or sinks into the system.

You need solar thermal panels and geothermal heat exchange system in the ground.

As far as control, a very simple embedded PC board running embedded Linux would be the "lazy" way to build it. It would actually be overkill, but there's an argument to be made for the COGS aspect of it.

Any number of relatively low cost embedded boards running very simple embedded software could monitor the sensor array, make decisions and activate valves, fans, etc. as needed.

I guess what I am saying is that you really can't fix the problem without engaging in a fundamental pivot from what we've been doing to thermally manage homes for the last, say, 100 years.

Having said that, it is a lot easier to sell a cool looking $250 gadget than asking someone to spend $5,000 to modify their home. Even though the gadget is very likely to not do much and the more extensive home modification is almost guaranteed to save the home owner thousands of dollars per year.

Talk about an opportunity for government stimulus!

> Having said that, it is a lot easier to sell a cool looking $250 gadget than asking someone to spend $5,000 to modify their home.

I think a little creativity in the payment model could help this problem a lot. The whole point of the system is to guarantee a decrease in the cost of heating and cooling, right? Doing some statistical analysis, it should be possible to estimate how much your customers will save. Tell them you'll pay their bills for them for the next X years. Charge them 90% of their current costs, pay the actual bills yourself, and keep the rest to pay for your system. After 3 years (or whatever statistically works out to be a comfortably-profitable threshold), they own the system free and clear and pay their bills themselves, again. Obviously they can pay off the system in full at any point, to allow for home sales and things.

> I think a little creativity in the payment model could help this problem a lot.

100% agreed.

> By itself it is nearly worthless (my not-so-humble opinion) for anyone but the most technologically incompetent thermostat users out there

Last year, I was living in a house with several people much, much fatter than myself. The living room was upstairs, where the heat collected. My studio was downstairs, partially buried in the ground, which sucked all the heat away. There were heated arguments over the thermostat settings.

Eventually these arguments resulted in a housemate trying to solve the problem by installing a "fancy" new thermostat downstairs - it was a programmable monstrosity with a completely unintuitive LCD display. To this day I am never sure if I ever actually managed to change the temperature it was trying to maintain, or merely dinked around with specifying a temperature that would have taken effect IF I'd put it into the program.

There was probably a manual but I really wanted to talk with the housemates as little as possible to find out where the hell it ended up being stored. I have written fricking 6805 assembly code, I am not technologically incompetent by any means, but I sure as hell couldn't be bothered to try to deduce this thing's operations from first principles.

(Arguably this means the thing did exactly what they hoped it would - make me quit bitching and put on a couple sweaters instead of maintaining a shirtsleeve environment comfortable for a skinny chick in a house largely full of 300lb folks. But I digress.)

> A real thermal management system for the home does not start with a high-design thermostat on the wall. You need multiple types of sensors in every room and multiple outdoor points.

Well, let's see: a Nest has an activity sensor, temprature, humidity, and an Internet connection, which means it can find out what the weather's like outside. Plant one of these in every room and you've got something starting to happen, if you're using local heaters rather than a central system. Admittedly you won't be doing this yet until they get the price down.

> As far as control, a very simple embedded PC board running embedded Linux would be the "lazy" way to build it. It would actually be overkill, but there's an argument to be made for the COGS aspect of it.

Care to lay wagers on what's inside the Nest? I'm betting it's exactly that. You may be willing to spend the time and money to get the thing going and write software for it. But there are a lot of people out there who are not. This is a really attractively simple version of that.

You're describing a level of commitment akin to "I compile my Linux kernels from scratch", this is for the "I open my Mac and it just works" crowd.

Let's see, for $250 you can spend $10 per room in sensors. Let's say you have 10 rooms. The remaining $150 can easily cover the cost of a fairly intelligent controller. That would be a better system with potential for far more intelligence, particularly if coupled with a simple zone system modification to the AC ducting (valves that can route air where it is needed and prevent it form going where it is not).

Something like that would have a far greater effect on the cost and efficiency of controlling an environment than a single expensive thermostat in one room.

That's what bugs me about these kinds of products. They never address the real problem. They are only there to find a niche that you can sell a gadget into with some pretext that may or may not exist, like the idea that thermostats are hard to program. OK then, try this one, it's cheaper:

http://www.smarthome.com/30429/Venstar-T5800-ColorTouch-Full...

The thermostat is not the problem. Homes (and buildings in general) are wasting energy because we are still approaching thermal management they way it was done 50 years ago. Here in the US it is not uncommon to cover the top of a commercial building with black tar (for waterproofing purposes). And then you wonder why it cost so much money to keep that building cool. These outdated ideas and methods need to change.

That's the problem.

Like I said above, you're interested in this at "I compile my own kernels from scratch" levels of commitment. The Nest is for "I open my Mac and it just works" levels of commitment.

You are quite correct in that the Nest is far from being a perfect solution. But you keep on neglecting to figure in the cost of all the time you spend learning about this stuff, installing it, and frobbing it. How many hours have you sunk into improving your home? What's your hourly rate when you're working? If you LIKE doing it then it's easy to discount that.

I'd like to improve my home's energy consumption too, but I'm not interested in spending days and days thinking hard about it, installing ugly boxes on the wall (the Nest looks a hell of a lot better than that box to my eyes, and this does matter to me because I'm an artist), and getting armpit-deep in ducting. Spending a little more money and not having to sweat all the details sounds like a great compromise to me; I might not get the gains you would, but having a smart system I can control from the Internet is still going to make some improvements!

Also, reading the Nest's pages, I got the impression that what they REALLY want it to be is one Nest in every room - the things will network with each other. They're just starting, small production runs are pricey. I would bet that they are eagerly awaiting the day when they can sell 3-packs or even 10-packs for what one costs now.

Ah, the whole house fan. I grew up in an area with 90-100 degree days/50 degree nights without AC, and my parents eventually got a whole house fan.

We had it installed in the ceiling in our hallway in a 4 bedroom house. I didn't care for it for a couple reasons:

It was dusty around where we lived. This means it was really good at sucking said dust into the house. Made everything get dirty faster.

Even when it was on at night, it didn't really seem to cool off the house much. Sure, if you sat in the wind path of your open windows, it was 50 degrees. If you weren't, it was still pretty warm. I'm sure it was really good at cooling our attic off though.

Part of me wonders if the fan was too large for the house to be effective.

Well, I am not doing an off the shelf whole house fan. Clearly some of the issues you mentioned are very real. Dust can be easily handled with filtering. My summer long experiment proved that you can cool a house and avoid using the AC unit for a whole summer. This is at least true where I live.

The next step is to come up with a plan for next year. Since a fan outside the downstairs kitchen window worked just fine, I don't have to rush to put in a commercial system. I can use all of next summer to experiment and find a better solution.

You can cool my house during the summer for about $10 per month. That's the baseline from which I'll judge all other solutions.