Monday, 19 December 2011

Christmas Electricity Demand

In my book I have a section on how electricity demand varies through the day - I compare the demand in winter and summer and there is a big difference - about 10 GW less overall and you can see a peak around 6pm in winter when we get home which does not appear in the summer. Since we are now coming up to Christmas, I have done a similar analysis to see what our electricity demand looks like over the holiday. Last year Christmas day was a Saturday so I have compared the holiday weekend with an average December weekend and also average mid-week December demand. There is a huge difference between the Christmas demand and the normal weekend demand (1).

From this you can see that on a typical Saturday we get up later and more gradually than during the week - between 8 and 11am compared to around 7.30am. Sunday we get up later still. Also though there is a strong peak at around 6pm throughout the week the overall weekend demand is about 5 or 6 GW lower - about 11% down.

On Christmas day we got up somewhere between the Saturday/Sunday norm - no doubt a bit of a trade off between adults wanting a lie-in while the children are far too excited to sleep. Then there was a flattish peak between about 10am and 1pm followed by a distinct drop  and almost none at all of the 6pm peak - just a tiny nudge up around 5pm.  I suspect quite a lot of the 6pm peak is usually cooking (two thirds of us have an electric oven rather than gas and nearly half have an electric hob too (2)) but on Christmas day we eat far too much at the mid-day meal and spend the afternoon nibbling chocolates and mince pies to the extent that we can't face any more dinner. Also we aren't vacuum cleaning or running the washing machine or doing any other housework - except presumably running the dishwasher.

On Boxing Day no-one seems to be getting up until at least 9am and the lunch time peak is lower and later - so maybe we are eating leftovers rather than cooking a proper meal. There is a little bit of the usual 6pm peak, however and a little more activity in the evening than on Christmas Day.

Overall we use about 8% less energy on Christmas Day and Boxing Day than the average December weekend day. So maybe we should have holidays more often :-)

Sources:

(1) National Grid Demand Data
(2) Saving Energy through Better Products and Appliances (DEFRA)

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