you / conserve energy / go to school or to work by bus / turn off your electric devices / you are not using them.

• A. 
  As you want to conserve energy, go to school or to work by bus and so turn off your electric devices when you are not using them.
• B. 
  If you want to conserve energy, go to school or to work by bus together with turn off, your electric devices when you are not using them.
• C. 
  Suppose you want to conserve energy, go to school or to work by bus and turn off your electric devices when you are not using them.
• D. 
  When you want to conserve energy, you needn't go to school or to work by bus and turn off your electric devices when you are not using them.