The intention of a Zero Carbon development might seem simple enough, but its meaning is often open to broad interpretation by both housebuilders and planning authorities, with very real consequences for carbon reductions and project costs.
By considering the methodology used, significant differences between one approach to a Zero Carbon development and another can be observed. Some of the key methodology decisions can be summarised as follows:
- Is the definition for buildings or the whole development (including non-building energy uses e.g. transport and street lighting)?
- Does it account for buildings overall across the site or is each individual building required to be Zero Carbon?
- Are embodied building emissions included?
- Are unregulated building emissions (e.g. plug-in devices) included?
- Is financial offsetting permitted, and if so, at what price?
A development which maximises the reach of this definition, including many of the components noted above, is more likely to encounter higher project costs but realise larger on-site carbon reductions than a development that seeks to limit coverage. However, in the eyes of many planning authorities both could legitimately claim to be a Zero Carbon development.
Planning policies concerning Zero Carbon development often lack sufficient detail to ensure a clear and consistent application of this ambition is followed. It is opined that the overall picture would be greatly assisted by the introduction of a nationally recognised definition for a Zero Carbon development.