Why are there sometimes large fluctuations in my day-to-day energy usage when nothing changes in my house?

The weather has the biggest impact on your usage because heating and cooling uses the most electricity. Even if your thermostat is set at the same temperature, your heating or cooling system will have to work longer to reach that temperature when the weather gets colder or hotter (You can see high and low temperatures when you roll-over the red and blue lines on your usage dashboard). However, fluctuations in your consumption may also be caused by other factors, such as the number of people in your home at any given time. For example, if you have guests or keep the heat/air on because you have pets, usage increases. Also, if you are home only in the evening one day but then spend an entire day at home the next, your usage will go up, especially if you are running appliances like your washing machine and dryer while home.