Saving energy
There are many ways you can save energy. This can save you money and help reduce CO2 emissions which is causing the green house effect.

Check out these sites for tons of info. and great advice.
http://www.est.org.uk/
The energy saving trust is a national organisation funded by the government and private sector

http://www.nef.org.uk/
The national energy foundation is a independent educational foundation.
To calculate how many kg. of CO2 you are using or saving click on the link below:
http://www.nef.org.uk/energyadvice/co2calculator.htm
DIY - Saving Energy, Tips and Advice
I will focus here on things you can do for yourself as a DIYer.

loft insulation
tank and pipe insulation
aluminium radiator panel
draught proofing doors
draught proofing casement windows
draught proofing sash windows
low energy bulbs
saving water
saving water in your home
saving water in the garden