Sunday, 21 August 2011

TV: standby or switch off

I was on the radio last Thursday (You and Yours, BBC Radio 4) answering the question 'How much would you save by switching your TV off at the wall instead of leaving it on standby?'. The answer is, not very much, although of course it depends somewhat on the TV and there are lots of other easy ways to save energy.

If your TV is less than 18 months old then the standby power must be less than 1W (1) which in money terms is about £1/year. For my TV at home, the manual says it uses less than 0.13W but it is probably even less as it does not even register on my power meter. However, older TVs often do have a more significant standby power drain. From a US survey (2) the average is about 3W and can be as high as 10W. This still isn't much in money terms: 10W would be about £10/year or 20p/week. However, as one listener was keen to point out, it is still a waste.

Well, every little saves a little but if you want to make a significant saving you need to look at significant usage. The average household electricity consumption is about 10kWh/day, so if your TV is taking 3W on standby, or 0.072 kWh/day that is probably less than 1% of your usage. You can save the same amount of electricity by:
  • boiling 0.6l less water (about 1 pt or 2 mugs full) per day
  • running one less washing machine load per fortnight (based on 1kWh/load) air dried or one load less per month if you use a tumble dryer (based on 1.8 kWh/load)
  • or 4 minutes less with the vacuum cleaner per day
  • or 1 hour less TV/day if it takes 70W - but an LCD TV could take up to 200W and a plasma TV up to 450W so you could save very much more
However, if your aim is to reduce carbon emissions then you had better not read a book instead unless it is a library book (see earlier postings Carbon emissions from watching TV and Carbon emissions from leisure activities). Generating 0.072kWh emits around 39g CO2 which is the same as:
  • 0.027 litres of diesel or around 0.25km (0.16 miles) in an average car new in 2009
  • air freight emissions from 7.2g grapes  (about 4 grapes) from California
  • production of 22g (less than 1 oz) beef or 71g chicken (2.5 oz)
I won't list the references for all these here but you will find them in my book plus lots more ideas.

By the way, leaving my mobile phone plugged when it is fully charged reads 0.0W on my power meter, so unplugging the phone chargers is not a significant saving. However, if you use a DVR to record TV that does need to be left on all the time and it is worth checking the power rating.

(1) COMMISSION REGULATION (EC) No 1275/2008 of 17 December 2008
(2) Lawrence Berkeley National Laboratory

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