This is a question that I could not have answered as recently as a week or two ago. I was actually surprised to find how little I knew and understood about our household electricity use, especially since I'm very interested in conservation. Also, I am very interested in alternative energy and hope to one day go completely off-grid with either solar or wind energy. I have recently started a project to create an inventory of all electiricity usage in the house and learn to predict what impact certain activities will have on the amount of electricity we use. We heat with propane, so this time of year is a perfect time for me to do this project, since I don't have to account for the electricity used for heating or cooling.
The first thing I did was go through our past electric bills and create a spreadsheet that summarizes them. I was able to download all of my previous bills from the local electric co-op's website. Armed with the data from every bill since we moved here (16 months, starting in July 2010) I began anaylzing the usage. A few things jumped at at me immediately.
First is that we were using more electricity last year than this year. In October 2010, for example, we used 626 Kwh (20.86 Kwh/day) while in October 2011 we use 377 (13 Kwh/day). That is a reduction in use of ~40%. I suspect that part of this is simply that since getting settled in we have been able to develop regular routines that are more conservation oriented than those first several months that we lived here. We were also still moving stuff in during the first several months, which means doors were being left open, etc. Another factor is that we often had a 3rd person staying with us on the weekends to help with projects, which is going to increse electricity usage some, especially when that person is not conservation minded. The last known factor is that our home is better insulated now than it was during our first months here. We are currently living in a mobile home, which is not the preferred structure for saving money on electricity. We were so busy with moving in and then doing other important projects at first that the home was open underneath for several months. As winter approached we finally enclosed it with insulated panels, which has surely helped energy use a great deal. Its possible that this had the greatest impact on our usage. Seeing the numbers now makes me wish we had made that more of a priority. There is one other potential factor that could have impacted our electricity usage, which I only now thought of. How was the weather last year compared to this year? After a bit of research I was able to find the information I wanted on the local University's Collge of Agriculture website. The average high temperature for last October was 71, compared to 67 for this October. It is possible that we could have used the air conditioner a bit more last year than this year, but I don't think the temperature difference is enough to explain the significantly lower electricity use, at least not by itself. I'm sure that the weather was a factor, though, along with the other items I've identified.
The second thing that stood out from looking through the data is that our electricity during 4 months is above our average monthly use. Those four months are June, July, August, and September. This is clearly due to using the air conditioner. Anything we can do to reduce the amount we use the air condioner will have a significant impact on our electricity use. In August, for example, we used 1451 Kwh, which is nearly 4 times as much as we used in October. Once Summer rolls around I will definitely be looking into ways of reducing that number.
The last thing that stood out isn't related to electricity usage directly, but the bill itself. Approximately 11% of the total we pay is for taxes and an environmental surcharge. These charges seem to be directly proportionate to our electricity use. In other words, the more we can conserve, the less we have to pay in taxes and fees each month.
Now that I know how much electricity we use on a monthly basis I'm not satisifed. I want more of a real time picture of our usage. I have recently started doing a daily meter reading, which I am tracking along with my other information. I am using the Energy Consumption Analyzer Android App for convenience, but a notepad would work just as well. After 5 days I have seen daily usage range from 10 Kwh to 18 Kwh. Why did we use 18 Kwh of electricity in one day? We don't know. I'm working on figuring that out. If we reach our goal of living with an off-grid PV or Wind system, however, these types fluctuations could have a significant impact. I want to learn how to identify and predict these things now and begin the process of shifting my mindset regarding energy use before we begin sizing an alternative energy system. For most people a fluctuation l ike that isn't a big deal. In fact, most people never even know that they have these types of fluctuations. Do you have daily fluctuations like this in your household energy usage? Do you know why?