Say, you want to be informed about the usage of resources at your place?
Solution 1: install counters or sensors for all of these and a few more, add some means of communication (cables or radio modules). Resolution of readings: 1 Liter for natural gas or water, 1 or 2 watt hours. Now collect the readings with second or even subsecond time resolution, transport them to your always on computer, feed them into a fancy database, add some more software to make nice diagrams to look at (include filtering, zooming, trending, transforming, and what not while you are at it). Try to extract correlations from this data, like the electric power produced from your solar panels as a function of solar azimut and ambient temperature. Get crazy about the data! Scream if the communication stops for half a day for some reason. Constantly fix the stuff for dealing with broken sensors, periodic replacement, overflow of counters of limited size, you name it. It's hard work --- trust me.
A reading taken once per second accumulates 86400 readings over the course of one day! A reading taken once per minute accumulates 1440 readings over the course of one day! Multiply with the number of sensors, 365 days per year ... the numbers become huge.
This is what I do: Record a reading every 10 minutes for slowly varying quantities like temperature and humidity (144 readings per day); a reading every 2 minutes for counters (electricity, natural gas, water), or 720 readings per day. And yes, I can find a lot of structure and phenomena in this collection. But that is for another evening.
Solution 2: Every Sunday evening take readings and put them into a spreadsheet like file. So that is 52 readings per year.
Optimization: Every first of the month instead of every Sunday. This is what I do, too, and what I did before the above mentioned, complicated, time consuming beast existed.
You still get structure in this reduced set. Fiddling a little with R will do wonders. You can see the seasons, no kidding (compare the pitch of the line during winter vs. summer months)! And you can see, that the new windows reduce the leaks in the house noticeably (compare height of the lines, first and last year in the diagram).
diagram 1: consumption per month, accumulated
Fun fact: we have cut the consumption of natural gas in half compared to the values of the first year.
The seasons can clearly be seen in a heatmap diagram, the reduction can be seen as well (diminishing hues of red), albeit not as prominently.
diagram 2: heatmap of consumption per month
Optimization: Replace the spreadsheet with a log book, a sheet of paper for diagrams, a pencil, and possibly a pocket calculator. And remember: that (sans the pocket calculator) is how the likes of Tycho Brahe, Johannes Kepler, Isaac Newton and many others derived their revolutionary insights about the physical world. Ok, it took them a lot longer than five minutes. If you have a spare moment, marvel a bit at how they did it, without computers. Read, how Ole Roemer induced, that the speed of light is finite in 1676. Computers weren't invented yet, neither were precise clocks.
If you would like to retrace some of this, get a second hand copy of "Do-it-yourself Astronomy" by Sidney G. Brewer (Edinburg university press, 1988). It asks for very modest equipment, and some time. Take your children along and have the appropriate amount of fun!
