Data centers in the U.S. use more than 90 billion kilowatt-hours of electricity a year. That requires roughly 34 giant coal-powered plants. What can a single developer do to make more energy efficient code? I will go through a series of not-so-serious experiments showing how various implementations made with Raspberry PI web server and power meter affect power consumption. How much energy does enabling WordPress caching save? What about optimizing queries? I will tell.