Anders Brownworth

Technology and Disruption

Graphing with the Proliphix IP Thermostat

A while ago I got a Proliphix IP Thermostat for my home. It costs more than your average thermostat, but in my opinion it is well worth the extra money. Disregarding the fact that it has proven invaluable when I can't remember if I turned the thermostat off before leaving the house, there are other very significant uses for an IP thermostat. One such use is to get a good idea of my energy use and the efficiency of my home by graphing the temperature and overlaying colors where the heating or cooling is running. In practice, the graphs end up looking quite nice as well.

Take a look at the graph. The main green area tracks the inside air temperature of the house as measured by the thermostat. When the heat is on, the green area is replaced with red. When the cooling system is on, you get a blue area. This gives you a visual idea of the efficiency of your house as well as how much energy you are consuming. After looking at these graphs for some time, you begin to see how costly that last one degree of movement is when you are heating or cooling your house against the external environment. If the temperature differential is great enough, it can take twice the energy to bring the house up just one degree.

You might be wondering how this works. I use RRDTool to record temperature and thermostat settings read from a Proliphix N10e IP Thermostat once per minute. RRDTool also generates graphs from the data in the database and I've coded it up to play nicely with the Proliphix line of thermostats. I will eventually make my code available through this website.

My next thought was, "what about outdoor temperature?". That is why a thermostat is necessary in the first place, so wouldn't it be interesting to see the temperature from outside as well on this graph? Unfortunately, however, N10e doesn't support an external temperature sensor. I suppose I could get a temperature sensor and hook it onto a serial port on my computer but it's really so much better when everything is all in one little unit and you query all data from one device. So I bought the Proliphix N20e instead. This version accepts two external temperature sensors as well as the internal one allowing you to average the temperature between several rooms to get a better idea of the internal temperature. "Nonsense!" I thought. I purchased an outdoor thermometer and am preparing to hook it up this weekend. If all goes well, I should have a light grey graph of the external temperature added to the graph above. The hope is that you'll be able to get an idea of the temperature differential at a glance. With a large differential, it might make sense to roll off the temperature target a little to save allot of energy.

We'll see how it goes. I'll post a newer version of the graph after I make the change and give it some time to fill in.

Comments (11)

John Mielko from Atlanta GA USA

After reading your article on proliphix, i purchased one .. very happy.. they should give you a cut of the sales..

please post the graphing tool.. it will be very handy

Anders from RTP

I (finally) got my external sensor up and running. Took some time to get it permanently installed on my house in a nice waterproof way. I had done the code modifications to get the external temperature into the graphs previously. To my amazement, external temperature graphing showed up the first time without any code changes! Over the next several days I hope to get the code cleaned up and released with some good examples.

Some less technical friends have suggested I make this into a hosted service, which I may do. It could end up taking time away from some of my other projects though so I'll see how many other people ask for it before I go diving in.

Michael Parker from Burlington, NJ USA

I just received my N20e today and got it all hooked up. I would absolutely love to use this graphing tool you speak of :)

Great looking graph by the way!

The things I do to keep 2 chinchillas climate controlled, lol.

Anders from RTP

After thinking it through, a hosted service won't be reliable enough to make the project worth it so I'm dropping that idea. I'll package the code up in the next few days and make it available. Thanks for the comments.

Michael Parker from Burlington, NJ USA

I look forward to checking it out! Thanks :)

P Mang from Toronto, ON, Canada

This will be fantastic. I got five 120e thermostats for my business and having graphing capabilities will make these thermostats even better. Can't wait to check your code out! Many Thanks!

Stan Sieler from Cupertino, cA

Hi ... I'm also interested in the RRDtool / Proliphix code. I just installed RRDTool 1.2.23 on my WinXP system and it seems to be working with the tutorial's example.

Anders from RTP

I spent most of Sunday cleaning things up. The project is leaps and bounds better than it was but I have one little bug in there that makes weekly graphs look as if the heat is on almost all the time so I have to go figure that out. As soon as that happens and I run it for a little bit, I'll post. I'm thinking this week though. I'll post a blog story on it. Stay tuned...

Anders from RTP

I've just released the source code that creates these graphs in a package called thermostat-graph. Download it an enjoy!

Deleff from YK, NT

I'm looking for Temperature Status/Control apps for the Blackberry Storm device to interface to the Proliphix IP Thermonstat, there appears to be apps for the iPhone devices.

Anders from Cambridge, MA

I'm not up on what exists for the Blackberry devices these days but the iPhone apps are written against the API which seems to be pulled from the live site. You can get it by asking Proliphix directly though.

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