Practical electronics projects is not the sort of work Artful Robot does, but here's a personal project with my new Raspberry Pi.
I wanted to make sure my office is as efficient as possible. It's fully insulated and mostly heated with a far infrared panel heater (these things are amazing), powered, of course, from 100% renewable electricity. But I wanted to understand how good the insulation is.
I took a Raspberry Pi and wired up two temperature sensors, and placed one outside and one inside the office. A Python script on the Pi takes readings every 5 minutes and sends the data up to this website where it gets stored in a database. Then using d3.js, this page presents the graph above (which will update itself automatically via ajax if you leave this tab open).
The dark blue line (normally the smoother of the two) is the temperature inside the office, the other blue line is the temperature outside the office, and the difference is shaded, too. These are measured against the left y-axis, in degrees Centigrade.
The red line is basically degreess change per hour ÷ difference in degrees.
So far I think that what this shows is that when the temperature outside is less than the temperature inside, there's about a 3°C drop in office temperature over an hour for every °C difference between outside and inside. Obviously over an actual hour the difference would be changing, too, I just thought it was easier to understand in hours. Interesting the heating dynamic is completely different and much more eratic. I guess that could be the effect of the sun shining on the sensor outside, but the air around being cold.
I'll be looking at this over the coming days - currently this data is all just on the shed as-is, with no heating inside, but soon the heating will be on, so that will be interesting to study, too. Perhaps the next step is to find a way for the Pi to report whether the heater is on...