The most obvious thing you can do when it comes to electricity conservation is to turn off all lights when they're not in use. As a reminder to turn off the lights, try hanging up little signs next to light switches. Use energy efficient or LED bulbs instead of the traditional bulbs. Run lessons and experiments on energy conservation in your classroom, so all your students and colleagues can understand it better. The more people understand its importance, the more serious they'll take turning off the lights.
Heating and Cooling
Set the thermostat to a reasonable temperature to ensure a level of comfort for both teachers and students. Fans can also help cool a room down. This way, you are saving energy by not relying on air conditioning. Programmable thermostats can also help you keep track of a temperature in a room.
Tech and Computers
Assure your computers are able to go into sleep mode when not in use. Turn off monitors if the computers are not going to be used again for a while. And always check to be sure all the computers are off at the end of the school day. Computers take up a lot of energy, so limiting their energy use anyway you can is good.