From 5 kilowatts to 5 watts

I was in Bletchley Park last week for the Over the Air event. One of the highlights was a tour of the museum in which we got to see a reconstruction of the first computer the Colossus. Originally the computers were left on all day but now they are only switched on from time to time for tours due to the high cost of running them (and for environmental reasons).

Colossus computer at Bletchley Park

Colossus computer at Bletchley Park

The machines use a whopping 5.5 kilowatts of electricity and standing near them you can certainly feel the heat. The sheds in which they are kept apparently get pretty warm in winter too.

iPhone charging

iPhone charging

My iPhone by comparison uses only  5 watts (approximately)  or 0.1% of the power usage of the Colossus!

The increasing energy efficiency of computers is formalised in Koomey’s law which states that “at a fixed computing load, the amount of battery you need will fall by a factor of two every year and a half”. This trend has all sorts of interesting implications as it will allow computer to become smaller and more ubiquitous in the future.

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Plotting Air Quality Egg data using R

I recently got an Air Quality Egg. The Air Quality Egg is a open source hardware project to measure air quality hyper-locally. My egg is located on the balcony of my flat in Brixton, London. The Air Quality Egg device has sensors which read NO2, CO, humidity & temperature and posts the data to Cosm. You can view readings and simple graphs on the Cosm feed page.

Air Quality Egg on the balcony of my flat

Air Quality Egg on the balcony of my flat

Plotting sensor data using R

I wanted to see the trends in the data so I wrote a script in R to curl the data from the Cosm API and plot it using GGPlot.

Here is the script:

Here are some example graphs of NO2 over a single day and several days. (Note I don’t have the latest sensor updates so the readings may be a bit off)

Plot of NO2 for a single day

Plot of NO2 for a single day

Plot of NO2 for a 4 day period

Plot of NO2 for a 4 day period