Each step in the curve on the rights indicates an individual energy-saving or emissions-reduction measure, showing how much it would reduce emissions by and at what cost per tonne of CO2 abated.
The further to the left on the graph a measure is, the more cost-efficient it will be. Measures in the green zone – for example, installing sensors which switch off lights when offices are empty – will pay for themselves irrespective of the price of carbon. Options further to the right will only be cost-efficient if the carbon price rises.
This category would include adding double glazing in older buildings, replacing boilers and fitting renewable energy-based systems. The magnitude of any reductions and their relative price will vary between buildings depending on factors such as age and design, management practices and fittings.