Power Pause Update

Last month, I described the National Grid's Demand Flexibility Service that my energy supplier, Good Energy, calls Power Pause. In that post I reported on the first three Power Pauses that took place on 29th November, 1st December and 5th December. On the first date, I saved 0.407 kWh of energy and recieved a rebate of £1.63 on my electricity bill. There were no energy savings on the two December dates and hence no rebates.

Photo 1: Dusk over Hereford

I noted at the time that the lack of energy savings on the December dates may have been down to the Air Source Heat Pumps (ASHPs) that provide all our heating and hot water. ASHPs work most efficiently when asked to maintain a constant temperature. As a general rule, the ASHPs are 'asked' to maintain a background temperature of 18 ℃ during the day and night. During late Autumn to early Spring, the temperature may be boosted to 20 ℃ during daytime (especially if one or both of us is at home or visitors are expected). This form of thermostatic control does not lend itself to energy savings during the early evening period.

When we were notified of the next series of Power Pauses, I decided to turn down the ASHPs by a couple of ℃ for the duration of the Power Pause plus half-an-hour each side of the Power Pause. The results were as follows:

• 12th December (17:00 to 18:00 h) - energy saved = 1.374 kWh, rebate = £3.67
• 14th December (17:00 to 18:00 h) - energy saved = 1.687 kWh, rebate = £4.50
• 19th December (17:00 to 18:00 h) - energy saved = 0.266 kWh, rebate = £0.71

The first thing to note was the rebate per kWh had dropped from £4 to £2.67. I don't know whether this is down to my energy supplier, the National Grid or just a function of the marginal price for electricity.

The second point of interest is why energy savings were much lower on the final date: 12th December. That is an easy question to answer because I forgot to adjust the ASHP controls due to visitors.

Temporarily turning down the heating for the duration of the Power Pause had no noticeable effect on room temperatures - probably because our house is reasonably well-insulated. Outside temperatures (7 ℃ - 9 ℃) were similar during all three Power Pauses.

In summary, turning down the ASHPs by a couple of ℃ for the duration of the one-hour Power Pauses had no noticeable effect on comfort, saved some energy, reduced carbon emissions and paid for approximately half-a-day's electricity.

There are another six Power Pauses planned so we will see how those turn out.