To have a bigger energy saving impact, try investigating how much energy families use at home. Use the results from your investigation to plan a campaign to get pupils to save energy at home as well as at school:
You could design your own questionnaire to investigate families' approach to saving energy at home, or use this questionnaire for some ideas, and energy saving tips. You could consider creating an electronic version of the questionnaire using free online survey software such as www.surveymonkey.com or Google forms which is better for presenting your results afterwards.