Let's suppose that you start with efforts to reduce your consumption of electricity. A good starting point would be to determine your monthly costs for each of the previous 12 months. Depending upon where you live, your monthly electric costs can vary quite a bit from season to season. You should therefore avoid the trap of determining a monthly average and then comparing it to your first month after adopting your green initiative. You'll get a much more accurate determination if you compare January to January and July to July. If you're trying to reduce electric consumption, you may need a full year after the initiative is implemented to get a true reading of whether the initiative is delivering value.