Tado Cooling – Intelligent AC control
kickstarter.com
kickstarter.com
Why do think I Nest is a gimmick almost bordering on a marketing scam? Because in only works in a relatively narrow range of applications (i.e.: small one or two room apartment). In a larger family home --and particularly a two story home-- it is worthless. You could save money with a cheap programmable thermostat. In order to really save money in such settings you need a zone system with one thermostat/sensor per zone, a multiple stage compressor (or multiple condensing units), a variable speed air handler, a high efficiency HEPA filter, attic exhaust fans and, ideally, a filtered outside air bypass system to take advantage of cool night air.
I am in the middle of renovating my home and have done all the research. Nest is a waste of time and money. You'd save far more money --FAR MORE-- buying a relatively cheap whole house fan to cool the house down at night (at least in my region). But, hey, everyone believes that technology is magical. Damn the math and physics. Hence the hype and sales.
Automating window units is a different game. These are devoted mostly to cooling single rooms. So now you have the equicalent of a highly granular zone system. If you have a home or office with several of these units an intelligent control system could, depending on traffic patterns and the daily flow of people in and out of the various spaces, have a big impact. This is different.
EDIT: I see the cargo-cult HN down-voting got started right away. You can't say anything bad about Apple, Tesla, Nest and others on HN. Of course, they never back-up their downvote because it's purely emotionally driven.
So, here's the challenge: If you think I am wrong about Nest tell me why and back it up. The comparison is between Nest and a cheap programmable thermostat. People's lives are reasonably regular and heat cycles in the summer are too. If you are intent on saving money a programmable thermostat will do wonders. I've been experimenting with this for three years knowing that we would have to redo our cooling and heating system in 2014/15. I've gone two full summers without running the air conditioner but for two weeks by rigging and intelligent $200 fan (meaning, I hooked it up to a $5 timer) to exchange air out of the house when outside air was cooler than inside. That move alone represented a savings of around $500 PER MONTH. See my point?
Nest allows controlling multiple thermostats from the app, I couldn't find if tado did the same.
Thus, your conclusion that Nest is a "waste of time and money" is fruitless.
However, the geolocation support does seem quite nice. The bar has been raised once again.
Some weekends I'm away, some weekends I'm at home. Most days I'm gone between specific times because of work, but sometimes I'll fire up the laptop and work from home.
That lack of awareness in my cheap programmable thermostat means any schedule I program into it would be wrong almost as often as it is right, which makes it only as good as any other simple thermostat with an up and a down button. Since it is wrong so much, that means I'm often wasting money heating or cooling a house that I'm not in.
Or I could just install a Nest, which not only would know whether or not I'm at home but which I could remotely control with my phone to let it know when I'm headed home or when I'll be gone all weekend.
Edit: The downvotes are most likely because you took something which is an obvious step up from conventional home heating and air controlling systems and has provable benefits, then called it a marketing scam based on vague anecdotal evidence, with a rather hostile "if you disagree then you're an idiot that believes in magic and fairies" tone, to boot.
My problem is that these things are being sold at my local Home Depot as some kind of magical device. This is a bedroom community of probably 100,000 to 200,000 homes. A huge number of them are two story homes of 2,000 square feet and above with three to five bedrooms. Nest is a waste of time for these people. I actually have data on this. I know six people with homes virtually equal to mine (planned community) who bought Nest to save money and could not tell you if they've saved a penny. If there's an impact it's that small.
Las summer I convinced one of those neighbors to buy a $200 fan and use it as I suggested. He immediately reported a savings of over $300 PER MONTH on his cooling bill. He saved over $1,000 last summer and expects to save over $2,000 this summer.
That's why I say it's a scam.
http://www.homedepot.com/p/MaxxAir-30-in-Industrial-Heavy-Du...
I've also used one like this:
http://www.homedepot.com/p/HDX-30-in-Pedestal-Fan-SFSC1-750S...
My neighbor bought a smaller one:
http://www.homedepot.com/p/MaxxAir-30-in-Industrial-Heavy-Du...
The idea is really simple. In our case these are two story homes with balconies. The fan goes on the balcony right outside the sliding glass door. You set it up to exhaust hot air from the house. Open all the windows. That will be your incoming cool air. The windows downstairs are fully open and the upstairs windows only four to six inches. Turn this on as soon as the temperature outside is significantly cooler than inside. There have been days when I've been able to get the house down to 65 degrees in a couple of hours.
I've also used the standing fan placed outside a ground level floor window blowing cold air in. Now you open the upstairs windows to push the hot air out.
So, you either pressurize your home with cool air or reduce the pressure (by sucking air out) in order to have cool air enter.
Not that hard to do. It takes all of five minutes a day to go through the open-windows-turn-on-fans dance and you save hundreds.
My next move is to automate this by integrating it into the ducting system as well as providing for a filtered cool air intake path.
The best part is that I saved the money I'll need by using this method during the last three summers. That money is going into system that should save me $1,000 to $2,000 per summer when compared to every house in my neighborhood. Nest can't even begin to compare to this performance.
Wow, and I thought my energy bills were high in California. Where in the world do you live where there's room to save $300/month?
(Of course there are lots of builders and major renovations where the $200 would still be considered a waste, I think they are targeting the ones that don't care about $200)
If I lived in an area where it's still hot at night and owned my own home I'd look into ways to store thermal energy at night when A/C units are more efficient. Here's a stupid example not fully thought out: I'd install a swimming pool as large as I could handle and chill that water at night.
A decent size swimming pool can easily have 25,000 gallons of water. Rough calculation: That's about 200,000 lbs of water. 1 BTU raises 1 gallon of water by 1 degree F. So, if you cool 200,000 lbs of water by just one degree you've stored 200,000 BTU's. A typical mid to large home A/C unit is 3 to 5 tons, which means 36,000 to 60,000 BTU's. As you can see, if you can efficiently cool down a large mass of water at night during high-efficiency and low electricity bills period you might just be able to sink heat from the house back into the pool during the day with a suitable heat exchanger. Again, seat of the pants stuff. I haven't thought it through in any detail because until I build my own house (on my bucket list) I have need to do so. So, call it a crazy idea at this point. Probably a bad one at that.
It's simply not efficient, even with auto-closing dampers, to zone and duct a multi-zone system with single condensing units.
You'd be much better off, efficiency wise, either: 1. Using mini-splits everywhere. 2. Going geothermal. You can support multiple units off a single loop. I did this in maryland. My 4000 square foot house had all the hot water and cooling provided by GSHP. My energy bills, keeping it whatever temperature I liked, dropped from about 400 a month in the winter to about 50 bucks. The wonder of 41 EER, 5 COP. Unlike the air source heat pumps, they actually publish real efficiency curves for various temperatures, and your pump actually work at close to expected efficiency!
I'm not seeing why that wouldn't be equivalent to two units.
Two small units
For the sake of argument, let's make everything otherwise equivalent. We'll say the small units are 1.5kw each
When upstairs and downstairs call for heat, you use ... 3kw When upstairs calls for heat alone, you use 1.5kw When downstairs calls for heat alone, you use 1.5kw
Ducting/blower loss from this setup (assumes two completely separate duct runs): 0%
One large unit:
3.0kw to make life easy (in reality, if you use small units, you often need less)
When upstairs and downstairs call for heat, you use ... 3kw When upstairs calls for heat alone, you use 3kw When downstairs calls for heat alone, you use 3kw
Ducting loss from this setup: 25-30% (at least, it's just the way it goes due to longer duct runs, more tees, etc. If you have, say, flex runs, it'd be even more)
It is essentially guaranteed to run for more than half the time of the smaller units (due to ducting loss, etc), making overall cost more.
Note that if you had mini-splits as the small units, the comparison would be crazily in favor of that. you'd have no loss due to ducting, they would almost certainly be DC based, and would be completely variable to actual load (even a "variable speed blower" on a large unit isn't), not 1.5kw on/off. Smaller unit efficiency is also almost always greater than larger unit efficiency.
Also note this is all a comparison of efficiency. It may be more cost effective to do one or the other (though it depends how long you own the house, insulation, blah blah blah)
You are absolutely correct. You end-up running a huge compressor for a small zone.
I've always like the idea of chiller systems and the general concept of storing what you need during times of high efficiency to bend the curve in your direction.
I haven't done any math on this at all but I've wondered what it might be like to cool the massive foundation slab most homes have as well as the ground directly underneath them during the night. Again, I haven't thought this through at all. Just thinking now that you would want to treat the soil in order to have a stab at improving heat capacity, etc. You could then use that during the day in a very careful way to compensate for heat flow. I almost envision radiator panels embedded into the walls with sensors to pump heat into the cold ground only as needed. Anyhow, there's probably a million things wrong with that idea. Air conditioning is one of these things that could be so much better.
Nest saved us on average $50-100/month vs the same months last year. I'm sure I could get far more savings with something different like you suggest, but again my options are limited. Nest paid for itself several times over, and I like the app.
There's the other element here which is just plain being lazy and wanting to be comfortable 100% of the time. No, I am not calling you this. Just making a general statement. I've walked into my home when it is 80 to 85 degrees F. I don't need the air conditioner to turn on an hour before I get home to get it down to 72 degrees (or whatever). I am perfectly fine getting home and turning it on (if the programmable thermostat didn't) and waiting 15 to 20 minutes while having a cold glass of water as it the temperature goes down.
Yet another reality is that the cooling process is far more efficient the longer you can wait. What I mean by this is that a good air conditioning unit is cycle limited to somewhere around a 50 degree F delta between outside and inside temperatures. That's governed by the physics of the heat exchange circuit. And so, in simple terms, if it is cooler outside your A/C unit will be able to cool your house much faster because it is able to pump cooler air into your home. There's a huge difference between trying to cool a house with 60 degree air vs. 50 degree air.
Finally, one thing you can probably do as a renter is to install a misting system around the A/C condensing unit (usually installed outside the house). Wet air has greater heat capacity than dry air and so the system will operate more efficiently. It is easy to rig a 12 or 24 volt solenoid valve to open when the compressor runs so the mister can provide moist air to the heat exchanger. This alone is bound to produce results significantly better --again-- than a Nest. And, of course, it wouldn't cost much more than $30 to $50 to implement.
In places where people can't be bothered to at least attempt to understand the situation and at the very least spend some time programming their thermostat, setting reasonable temperatures and taking five minutes to open windows at night, well, yeah, Nest might serve in a range from placebo to small savings.
My key argument is that a single thermostat isn't a solution to a systemic problem. Most homes are not designed to be efficient in this regard, which is sad.
You're probably right, had I figured out how to use it (that's what I replaced with Nest). Like most things it's probably most efficient when I put the effort in, but that's the magic of Nest -- a huge work:savings ratio. You're right about laziness. Banking on laziness is a great business model -- find something people are lazy about, automate it to be maybe 60% of optimal and charge $$$$ for it.
> Wet air has greater heat capacity than dry air and so the system will operate more efficiently.
I grew up in a house with a swamp cooler now that I think about it. It worked pretty well.
We just had an offer accepted on a home, so I'm bookmarking your comments. Maybe I can implement some of them soon!
1) Seems like a lot of data, what exactly is it communicating and to whom? What are the privacy policies?
2) What happens if/when the company stops running its servers? Does the device continue to work or will it become junk?
I have a Nest Thermostat that I bought before Google acquired Nest, which raises another general issue of your device having an evolving T&C to use.
That's about the right amount of data to do an HTTP POST home every minute with the basic temperature, humidity, what its internal IP address etc is.
Which seems completely reasonable to me. 5 megs is reasonable for your acks and occasional commands. I don't think there's anything suspicious about those numbers -- I'd probably have provided similar ones if I was designing this system.
http://www.coned.com/energyefficiency/residential_directload...
[1] http://thingsquare.com/customers/ [2] http://www.contiki-os.org/
Yes, I know, I run a Windows Phone and don't own Android or iOS devices but companies should at least give people the ability without pay walling it.
It's quite similar to the name Taco, which is an 80+ year-old American HVAC company [0]. I hope they don't get in trouble in the U.S.!
Other than that, great idea!
"The name tado° is derived from the Japanese greetings 'tadaima' and 'okaeri'. Loosely translated, they mean 'I am home' and 'welcome home'."
allows record and playback of IR codes as well as search of LIRC
also, if you are building an IR database, would you consider sharing the IR codes with the community?
after all, I'm sure Ken Sheriffs library and arduino are open tools that are likely helping you quite a lot in the early stages...