This month’s Resurgence includes a new column on these issues written by Lorna Howarth. She refers to the Global Commons Institute (http://www.gci.org.uk/) and their notion of ‘Contraction and Convergence’. They have a much tougher calculation: that with a global population of 6 billion, the planet can only sustain 2 tonnes of emissions per person. That would make our target 4 tonnes a year. She quotes the UK average as 12 tonnes per person. But she also quotes the take-up by trees from Future Forests (http://www.futureforests.com/) as one tonne of CO2 per mature tree, which is far higher than 5 tonnes per acre of woodland. Checking with her sources, it turns out that Future Forests actually use a rough measure of 5 mature trees per tonne of CO2. This is certainly closer to our earlier figures. It suggests 75 trees at Hedgerley to make up our 15 tonnes saving, which must be about right. I’ll go and count them at some point.
She gives some other useful figures:
- average car use in UK 12,000 miles, LPG emits 25% less CO2 and costs around £2,000 to convert a car to.
- Air travel – their own carbon calculator (www.resurgence.org/carboncalculator) multiplies the usual CO2 figure by three because it is emitted in the upper atmosphere, with is 3 times more damaging.
- single glazing can lose 50% of the heat in a house.
Lorna also has a argument relevant to our logs – that burning wood is carbon neutral since the CO2 emitted during combustion will be sunk by the growing replacement by the woodland. I hope this is true. Need to check further.
This issue of Resurgence also has an article on the Hockerton Housing project in Nottinghamshire (www. hockerton.demon.co.uk). These are purpose build eco-houses in a community setting which come close to total energy self-sufficiency and zero emissions. It took them 4 years to get permission for their 26-metre wind turbine (half the cost and twice the output of their solar panels). And their glazing is triple- glazed and argon-filled.