@cheesemaker You're right about the guidance element. I did a little searching and couldn't really find anything. There are other tools that I'm going to hunt for, but I suspect this really it's a vehicle to try and get people to get into the habit of offsetting their carbon footprint. That's likely what most buildings will need to do by 2050 to meet the global targets of net zero carbon across all buildings. So in a generation's time, it becomes normal for you to pay towards neutralising your emissions. At the moment it would cost me anywhere between $50-$100 a year to offset my 50tonnes of carbon/year...which seems low.