This forum is about wrong numbers in science, politics and the media. It respects good science and good English.
I just noticed that the Lib Dems have quoted some numbers for the first time in a while in connection with climate change.
"Liberal Democrat Leader Menzies Campbell has launched the Climate Change Starts at Home campaign, cementing the party’s position as the greenest of the three major parties."
"The Liberal Democrats are targeting housing in the battle against climate change because it emits 27% of Britain’s carbon dioxide. This is compared to less than 5% in Sweden, which is considerably colder. If Britain had Swedish standards of energy efficiency, the average British household would save £385 a year on their energy bills."
So the whole basis of the campaign seems to be that we in Britain have an excessively high percentage of domestic-related CO2 and need to get it down to the levels of the Lib Dems' favourite country, Sweden. THe Lib Dems are blaming the whole of the discrepancy on relatively poor UK home insulation. Given the track record of Chris Huhne being associated with duff statistics, I decided to check whether the 27% figure is confirmed by DEFRA:
"In 2005, 37 per cent of carbon dioxide emissions were from energy industries, 22 per cent from road transport, 18 per cent from other industries and 15 per cent from residential fossil fuel use."
So it looks like the real percentage is 15% for the UK, just over half of the 27% figure the Lib Dems are claiming.
To check the Sweden figure I used data from the International Energy Agency:
This table gives 15.4% for the UK, confirming the DEFRA figure, with 6% for Sweden rather than the "less than 5%" claimed by the Lib Dems. The UK is slightly higher than the European average of 12.1%.
From the IEA data the list of countries with higher domestic CO2 percentages than the UK are:
Georgia 20.7%, Indonesia 16.0%, Nepal 28.1%, Uzbekistan 28.3%, Austria 15.9%, Belgium 17.4%, France 16.2%, Hungary 16.0%, Italy 17.0%, Switzerland 25.8%, Ukraine 16.6%, Iran 23.1%, Yemen 17.1%, Benin 19.9%, Cameroon 20.5%, Ethiopa 16.4% and Haiti 18.2%. This list doesn't suggest to me that the percentage has got very much to do with the efficiency of home insulation.
Domestic CO2 emissions as a proportion of national emissions are not a reliable indicator of home efficiency anyway. If a country has no industry, for example, then we can expect a larger proportion of CO2 emissions to be from the domestic use of fossil fuels, even if there is no difference in average home efficiency. A more reliable indicator would be the annual amount of CO2 emissions per household.
That's right- the percentage of domestic CO2 out of total CO2 for a given country is a very poor indicator for what the Lib Dems are trying to prove. A high percentage could indicate that the country tends towards a service economy rather than a manufacturing economy. If a country uses a lot of nuclear or hydroelectric power, that could significantly reduce its electrical generation CO2 and increase the CO2 percentages for the other sectors. If domestic electric heating happens to be popular in a given country, the CO2 from that would normally be attributed to power stations rather than domestic users. In cold Scandanavian countries, district heating with heat piped in from CHP plants is often used, so the CO2 from that would be attributed to the CHP power stations rather than domestic users.
I managed to find a source for the 27% figure- it seems to come from the Energy Saving Trust quango and it includes total residential electricity consumption as well as residential fossil fuel use. But including electricity consumption for domestic CO2 seems dubious. The normal practice is to allocate CO2 on the basis of where the CO2 was actually produced, so electrical generation CO2 is normally attributed to the power station rather than the consumer. If this line of thinking was taken further, a domestic consumer who buys a TV set originally manufactured in China could be claimed to be responsible for the Chinese CO2, which seems silly.
So I think I know how the 15% got bolstered up to 27% for the UK. But I'm pretty sure that this practice hasn't been applied to the Sweden figure.
And we have yet another example of how to manipulate the populace. Combine numbers in as many ways as possible until you get one that makes your point. In a way, it is an inverted data dredge.
It is also a form of Conjuring. The conjurer gets you to look the other way (sometimes by doing it before anyone ever shows up to the theater) when he does his trick. Policy makers do it by presenting numbers without presenting the alternate numbers. I understand the problem the policy makers face though. Whether you are Jeb, mad at having lost your Roto-Tiller to thieves and expecting police to do something about it, or Margaret Thatcher presenting Global Warming as a crisis for the future, you have to make a decision and try and get others to make the same decision. Do you present all the possibilities or just the ones that support your side.
Any difference with Sweden has less to do with home insulation and more to do with the large ammount of heating by heat pump in Sweden. I am pretty sure that the energy expended in installation of these expensive systems is not tabled under the domestic heating column, where it by rights should be.