Wednesday, April 29, 2009

Four simple actions

I wrote an article, "We need a plan that adds up", for The Guardian and For the Grauniad I also created a new graphic which I thought I would show here.

Four simple actions that make significant energy savings, and one that doesn't.
The left-hand column shows five contributors to the average energy consumption of a typical reasonably-affluent Guardian reader. The right-hand column shows the reduced consumption, post-action.
Any comments? Would the figure work better if I put the phone charger in the middle instead of at the bottom of the list?


Nicolas said...

Are all the types of meat equal? What is the environmental impact of eating local food rather than imported ones (for fruits and vegetables, mainly)?

Personnally, I would be reluctant to use the word "simple" (simple actions) as the remaining two may be problematic for some people (family with kids, tight schedule, family abroad) and it may sound a bit patronizing. Just a thought.

I'm pleased to see that the Guardian was so shaken by your article that it became the Grauniad.

Phil said...

Nice! I think the phone charger should go in the middle for emphasis. Will you be mentioning the different relative sizes of the boxes if the unit of measurement is tonnes C02 equivalent per year? I was shocked by the disproportionate influence of meat... The article would probably be better off left uncomplicated though.

Nicolas said...

A quick computation tells us that the entire energy spent in leaving the phone charger plugged for a year may be offset by driving 2.7 miles less just once. Do you think this could make the argument more palatable?

DanH said...

Nice clear exposition of the situation.

Two suggestions: firstly, since the "before" column for heating mentions buildings being leaky, maybe the "what you can do" column should mention loft and cavity wall insulation, and double glazing.

Secondly, be a little cautious about asking people in the UK to turn down thermostats on grounds of energy sustainability. Mortality statistics available hereand here suggest that the risk of a UK resident dying of hypothermia is within an order of magnitude of (about a factor of 4 less than) the risk of a resident of the world dying as a result of climate change.

Unknown said...

David, any chance you could take a look at:

Someone's disputing some of your figures...

Keep up the good work!

Joe said...

ok I can do this one. From the footnote on page 29:

'For the distance travelled per day, let’s use 50 km. This corresponds to
18 000 km (11 000 miles) per year. Roughly half of the British population
drive to work. The total amount of car travel in the UK is 686 billion
passenger-km per year, which corresponds to an “average distance travelled by car per British person” of 30 km per day. Source: Department for Transport [5647rh]. As I said on p22, I aim to estimate the consumption of a
“typical moderately-affluent person” – the consumption that many people
aspire to. Some people don’t drive much. In this chapter, I want to estimate the energy consumed by someone who chooses to drive, rather than depersonalize the answer by reporting the UK average, which mixes together the
drivers and non-drivers. If I said “the average use of energy for car driving in the UK is 24 kWh/d per person,” I bet some people would misunderstand
and say: “I’m a car driver so I guess I use 24 kWh/d.”'

Seems fair enough to me.

Joe said...

On the other hand, it is fair to point out that the 'cartoon Britain' seems to allow 40 kWh/day for transport per person rather than the average of 24 kWh/day.

Maybe I'm missing something about what has been included in the 'transport' category.

Nicolas said...

Joe: a driver will use 40kWh per day because of his driving. Since 60% of people are driving, this amounts to 40*.6 = 24kWh per day on average. The cartoon is there to determine the changes that people can make in their lives. Therefore, it seems more informative to use the number for a driver (40 kWh per day) and ask the non-drivers to dismiss this information entirely rather than to use the average number (24 kWh per day) which non-drivers will dismiss anyway and which will be misleading to drivers.

Put it another way, if I stop driving, what will happen:
- if I'm already not driving, the improvement is 0
- if I'm driving, the improvement is 40 kWh per day

The quantity of 24 kWh per day is incorrect for both kinds of people, it is only valid for the virtual "average British".

Joe said...

Nicholas, I sort of agree with that rational, but in the cartoon Britain section aren't we thinking about the nation's energy budget? I think there is a contradiction implicit in the approach of using 'personal' usage when considering an energy budget that adds up.

David MacKay FRS said...

To get best results from your conversation, Please Read the book!
The typical driver of a car uses 40 kWh per day.
British transport in total also averages out to 40 kWh per day per person.
"How can this be?"
Use your noggin! There are other forms of transport, not only cars! For example, ships, road freight, and planes.

David MacKay FRS said...

PS - thanks everyone for the helpful feedback on the diagram. Amusingly, the Grauniad redrew the figure when they published it, and introduced a fairly substantial typo. Here is their version...

(See how long it takes you to spot it. I didn't see it until a commentor pointed it out.)

Nicolas said...

Yes, David. Because of methane, you do increase your workplace temperature when you have vegeterian meals six days out of seven.

DanH said...

Am I getting my arithmetic right, in thinking that a car that uses 40kWh to go 50km is in band "M" of the UK fuel economy labelling scheme? Is that really where a typical car is at?

David MacKay FRS said...

"40 kWh per 50 km" is roughly the same as "33 miles per gallon" (which is I think fairly average and typical). For a complete conversion service for petrol and diesel, between all the crazy units, see my petrol-diesel-mpg blog. If you would like to add the bands to that blog or to my book's wiki, that would be grand. Thanks, David

GHS said...

BTW, great video and well worth the time it took to tape. But I was surprised to see that the flying/telecon ratio was only 35:1. I would have thought the savings would have been considerably greater. Is there more on that in SEWTHA? Please share a page range if that would save time in posting. Congratulations on the book (and Grauniad article.) Keep up the good and useful work.

David MacKay FRS said...

Video conferencing: it's a very rough estimate. I reckoned the main energy costs would be the cost of manufacturing the extra kit, and of leaving it on a lot if you wanted it to be as convenient as a phonecall. Making a new PC every two years costs 2.5 kWh/d. So buying a new VC system every five years(?) maybe costs 1 kWh/d.

David MacKay FRS said...

@Nicolas, who asked "are all types of meat equal?" - the answer is no, beef uses more energy and chicken uses less. It's in the book. In the chapter called "food and farming" -

Ray Lightning said...

Vegetarian diets are good for the environment, but a more direct impact is on fresh-water utilization, not on CO2 emissions.

Fresh water is a very sensitive variable, and there is only a very limited amount of fresh water in circulation at several regions of the world. At several places, these resources are over-used and water tables are running low. This will translate into severe famines and food shortages if not managed properly.

Agriculture is the king of the fresh-water demand, and particularly the meat industry takes a huge portion of fresh water (indirectly in the farm of animal-feed cultivation). Most often, this animal-feed is imported from abroad, and the environmental impact is felt elsewhere.

GHS said...

David - Saul Griffith, whom you may know as a wind entrepreneur and inventor, has published work that attempts to calculate both personal and global energy usage today, and in the future. ( One item he describes is his 2007 air travel which he describes as "unsustainable" at 105,000 miles and estimates to "cost" 7,462 watts. (He uses 1.4 mega joules/km to calculate that.) Sorry to bother you with a question I would not ask had my math education been better, but how does his "watts" correlate with your "kWh/d"? Thanks for turning on this light bulb in my understanding.

David MacKay FRS said...

I know Saul well.
1 kWh per day is pretty much the same as 40 watts. 1 kWh per day is what you are using if you keep a 40 watt light bulb switched on all the time.

Read my book for this and more.

DanH said...

Thanks for the heads-up about the petrol-diesel-mpg post. Turns out that, although I had the arithmetic right, I had my starting assumption about the specific energy content of petrol wrong. The 40kWh per 50km car is actually in band "F".

I'm still not sure about this being typical - I seem to recall last time I wandered around a car showroom, almost all of the vehicles I saw were in bands "B"-"D", which would be between 20 and 34 kWh per 50km. Of course, the showroom I went to might not have been representative - what do folks think?

Annz said...

Dan H - as noone else has responded to your question, although I am not familiar with the bands you refer to, I think I infer these are largely related to miles per gallon. If not, please ignore what follows.

I don't have the relevant figures, but I would expect the difference to be made up in part as follows:
1. The figures and bands you refer to are being used to sell the cars. In these circumstances, it would not be surprising if these were perhaps amongst the best achievable rather than the average. For instance, how many people are in the car in the test, how heavy, how evenly is the weight distributed, how much are they moving during the test, is the boot empty? Exactly how is the car driven - by a real average driver, who might have had a bad night's sleep interrupted by eg being woken up by children, or noise outside their house, or by an expert driver paid by the motor car manufacturerer? The latter would know how to achieve the best possible results (e.g. where possible driving in the highest possible gear at as slow a speed as possible, with minimum acceleration and deceleration? Is the car tuned for maximum performance or for the best figures on this? When was it last serviced - 6 months ago (average) or last week?
2. Finally to be fair to the car manufacturer, the figures will have improved because of engineering design to achieve this, over the last 10 years, as it became seen as of more importance. Not all cars on the road are new. I would expect the improvement in the published figures for new and older cars to be made up of a mixture of the above, as well as other factors. The result will be better figures, in general, when comparing like for like, for new cars than older ones. (Although, despite the car manufacturers having persuaded the UK government to introduce a "scrappage" scheme, there are other issues in determining how beneficial it actually would - or wouldn't - be to replace all the old cars with new ones.) The bottom line is that the new cars improved figures are likely be a combination of engineering improvement and increased competency on achieving the best figures (e.g. aas above). As figures such as these are seen as more important, so they are liable to be improved in ways such as the above. These would of course all be real improvements to the real average, if only all journeys were entirely like the test journey. Only they aren't. (Really this should perhaps be called the Target Paradox, to join the Jevons Paradox. It is the variance that often happens in practice between achieving a target and achieving what the people who were the cause of the target being introduced were actually trying to achieve just before the target was set. The Target Paradox can be seen in many large organisations. It is especially significant where those behind the target being introduced are numerous, eg the general public.)

DanH said...

Annz: thanks for the suggestions. As far as your point 1 goes, the test conditions are quite tightly specified by law (see here and earlier directives referred to therein). The most prominent feature of the specified conditions is that they include separate simulations of urban and rural driving, and the band comes from taking a weighted average of the two.

Chris said...

I wonder if there is away of presenting the point in a positive way, i.e. if you are trying to save energy by turning your mobile phone charger off then well done for making an effort. Now that you have done that here are some actions to take on next that will save much larger amounts of energy. The advantage is it keeps a positive vibe going and prevents distracting arguments, as really the goal is to convince someone to turn their heating down and wear a jumper rather than beat them down about the mobile phone charger bit ! Then the fact these other changes are more effective would act as an incentive to consider doing them.

e.g. Someone who is a well meaning person, but works in say disease control and knows nothing about energy might be dutifully turning their mobile phone charger of for years as they read this was a good idea. If you then say to them they are wasting their time it might make them dispondent or argue against you. Saying well done and here is something even better to do is presenting the same data just in a different way.

Just saying as another way of looking at it.

Practically speaking turning the lights off when you leave a room is a similiar habit to unplugging your mobile charger in terms of behaviour anyway. i.e. psychologically they cost the same to develop the habit. It just happens one is more effective than the other in cutting carbon.

Getting people to drive less and turn the heating down/wear a jumper is a bigger challenge and will cost them more effort and requires a bigger change in lifestyle.

I always wondered if maybe we should try to get a just one thing message across i.e. if you wanted to do one thing in your life to help cut carbon emissions, then what would be the advice we would want to be common knowledge ?

"turn off your mobile phone charger" ? no :)

"use the car less"
"turning the heating down or off"

i.e. get a simple message out as things like 10 things you can do to save energy will be instantly forgotten most likely.

maybe "turn the lights off, drive less, turn the heating down"

even that might be too much.

dressing gowns are pretty useful for the heating option ! maybe we need some fashion people to revamp the dressing gown as a fashion statement and people would turn down the heating as a result of wearing them. Trouble is they would probably just open the window...

Really useful work you are doing.

all the best