Anyone with any good insights? For the time being I will run the remote egg from a USB power supply via the FTDI port – not terribly convenient, but it works.
The Dust sensor arrived tonight for the Air Quality egg arrived today – and has now been installed, and the feed is working.
(Click for larger image)
The measurements seem a bit wrong though – possibly the Dust_r0 of -1 is somewhat wrong.
Btw. I followed the instructions here for the physical installation. I will post pictures later.
To sum up :
The air quality egg outputs 2 values per sensor – the raw resistance measured, and a interpretation of that based on a number of factors including a average calibration value (R0), humidity, temperature and a factory supplied set of graphs helping to turn the raw resistance value into a ppb (Parts per billion) value for human consumption.
So these are the values from our AQE (Now placed outside in a semi rural placing)
and these are the values from another AQE in the UK (also placed outside in a rural setting)
and as you can see – the raw resistance is not that far apart taken over time, but the interpreted values are extremely far apart.
I would expect both of these to show very small CO values, and there is clearly something wrong in the delta between the 2 interpreted graphs.
I suspect mine is wrong – as the values are way too high, especially seeing it’s windy outside, and the air “feels” good to me.
The manufactures of the AQE has a blog posting about how to set the R0 (or calibration resistance) of the egg to change the calculations – so that is one way of correcting the interpreted values, but it is a bit cumbersome, as it requires you to upload new software to the Arduino clone, running it, and the re-uploading the base station software. For experimentation this seems a bit long winded.
What I feel is needed is software to do this on my own computer – so I may have to sit down and get cracking on this – after all this is the real advantage of all the open source software!
Data from our Air Quality Egg measurements – bear in min that the values (except for humidity and temperature) are relative and indicative.
It’s quite clear that I need to calibrate the sensors of the AQE before i get much sensible out of it. So starting with the CO sensor I have hunted around for a reference source and found this :
The only other way I could think of calibrating this is to use the Carbon Monoxide alarm we have in the house – it’s got a display that shows CO ppm over the last 3 weeks. According to the manufacturer it starts at 10 ppm.At the moment it shows 0ppm though – so maybe that’s one place to start….
I am a bit puzzled by the data I’m collecting from my AQE – so I started reading up on the sensors and found the following
CO to 9ppm with an accuracy of 1ppm. Normal atmospheric ranges are up to 20ppm
NO2 to 100ppb with an accuracy of 1ppb. Normal atmospheric ranges are up to 400ppb
[From airqualityegg – Data Quality]
But what I’m seeing from my AQE is :
Which would indicate that I should be dead. But as I’m still fairly active and feeling well I decided to look at someone else’s measurements
And I found one outside Chicago
And after looking at a few others I concluded that the AQE sensors will indeed need a bit of calibration to deliver believable results.
This seems to require a bit of programming and changes to what is in reality “hard coded” values (i.e. they will need changes to code and data that will need to be uploaded to the Egg. So I would expect this to take some time – and I am glad that I have the tools to do this – as one of the first things I did after getting the AQE was to upload new software to the base egg.
Pleased to see that there now is a UK distributor of the Air Quality Egg – here.
My Air Quality Egg can now be found at http://airqualityegg.com/egg/103443, and has started monitoring the quality of the air in Busbridge, Godalming.
The gas usage in our house :
As you can see from the graph (not easily mind you) over the first 6 months of the year we used almost the same amount of gas as during the first 6 months of last year. Not bad considering we have had a much colder start to this year, where we have actually used the heating in the house more.
At the moment we are down to the lowest gas usage for any period measured so far – with a average of 1.22 units per day over the last 72 days, which is almost 30% below the same period last year.
This is in no small part due to our refurb of our conservatory, which had 8 glass doors leaking heat through non-insulated gaps between the doors and the door frames. This has now been properly fixed, and we are seeing the results already.