Do not use a Screen Saver!
Change the power management settings on your PC to go into ‘sleep’ mode when not in use. The surge of power used by a CPU to boot up is far less than the energy used by the unit when left on for over 3 minutes. A computer left continuously running will emit 2161 pounds of CO2 in a year. Turning a computer off at night so it runs only 8 hours a day computes to a reduction of 810 kWh per year, or a 67% yearly savings.
Join Global Warming Pledge on WAYN (Where Are You Now?).