My understanding is the peak usage period each day in the summer is about 3 to 6 PM. A few days ago the forecast was for 95F+ for a couple of days. The local electrical utility cooperative sent an email asking members to reduce power consumption between 3 and 6. I complied by cutting off my AC during that period. Before I cut it off I lowered the thermostat a couple degrees so the house would cool down a bit and become a thermal storage tank. It seemed to work pretty well as the temperature inside the house only reached 79 or 80 each day by the time the A/C was turned back on after
- I decided to use the programming feature on the thermostat to do this every day.
My utility has an hourly usage view mode and I see the power consumption pattern shift dramatically drawing peak usage earlier in the day when the A/C lowers the set point until 3 PM when the set point is raised to 82F using 2.5 to 3 kW. Then the usage drops to a fraction of a kW until the thermostat is lowered to 77F after 6 PM where it rises to 3 kW for one or two hours until the outside temp drops and power usage drops accordingly.
I don't know yet if this is costing me money or saving me money. There currently is no time factor on the metering currently. The distribution charge by the utility is lower after a base amount of 300 kWHr each month, so the incremental rate is lower than the average rate. Once I have more data I will add up the costs each day and see if I can tell any difference.
But what is notable is the peak demand shift from 3-6 to the periods before and after that period. If the utility is asking us to cut back on demand, it must be important to them. My utility is a coop and so is not motivated by profit. This could be extended by using thermal storage of some sort. I have read about incorporating beads of coconut oil or a particular type of paraffin into wallboard as a phase change material. Coconut oil melts over a range of 74 to 80 degrees (approx) and so would be good for this. There are paraffins which melt in this range as well. During off peak hours the cool air can be passed through a tank of these materials for thermal storage, then when cooling is needed the A/C is left off and the warm air looses heat to the phase change material as it melts. I've not been able to find good info on the latent heat of melting for either of these materials. The coconut oil would be the least expensive, but there is little good data on it. So I can't estimate how large a tank would be needed.