The temperature lab shows results for three temperature probes. The red curve is from a probe dangling from an office desk, the blue curve is from a probe outdoors and under a roof (so it is not exposed to light) and the black curve is from a probe taped to the top exhaust port of an iMac computer. The figure below diagrams the results over ten days time and main points are given below it.

Main Points:

• When the screen is off (screen dimming) the iMac is about 10 degrees hotter than ambient. With the screen on the iMac runs about 20 degrees warmer.

• Cycling of the air conditioner compressor is seen when the office temperature is less than outdoor. The cycling represents about a 3 degree variation. When the air conditioner is fully loaded the cycling is less indicating that it is continuously on instead of cycling in the interval of its thermostat.

• The ten day weather trend is noticeable in this graph where the temperature increased an average of about 20 degrees over five days and then decreases back about 20 degrees.

• Night and day oscillations in temperature are immediately noticeable for the outdoor temperatures.

• Use of the iMac computer during office hours, beginning at about 8am every day is noticeable by a sharp rise in temperature followed by 5-10 degree fluctuations as the screen saver goes on and off.

• As a storm front passes the temperature decreases quickly and then the temperature slowly decreases on average over the next few days.

Improvements:

• The Temperature Lab is updated in a web browser by the user refreshing the page. This can be automated with a simple refresh meta tag or a Java script.

• This is a simple example that took just a few minutes to setup. More complex examples can include feedback controls and associated state display.

• The same systems can be used to monitor and control a wide range of processes and operations, albeit with different sensors or database queries.