Hi, I made a thread a few weeks ago asking people how they calculate their heating savings and explained how I do mine using Excel. The topic veered off from the subject and instead of bringing it back I thought I should just start a new one, because I just have one question. I used to heat with baseboard heating. My last year was in 2005 and I have the price and kilowattage used in that year which tells me how much electricity I paid. I had my pellet stove installed at the end of February in 2006 and I also keep track of all the bags purchased. My question is simple, I hope I can explain it right: For 2006 and 2007 how should I calculate my electricity costs against 2005? Imo there's three ways to calculate the cost and I am not sure which one is correct: First - Use 2006 kilowatts usage and apply 2005 rates. Second - Use 2005 kilowatts usage and apply 2006 rates. Third - Calculate the annual cost for 2005 and 2006 and get the difference. So which one is the correct one to use? I am divided on this.