The exact scope of a sustainability report will have to be agreed on via consultations with your local planning office, however, your LPA's guidance on such matters comes from central government and as such we can expect a certain amount of similarity from area to area.
In short a sustainability statement includes your confirmation of the understanding of regulatory minima like Part L of the building regulations, but may also include supplemental sustainability initiatives such as BREEAM aspirations above minimum.
This guidance comes from the NPPF relating to sustainability:
Any sustainability report, which might be prepared in conjunction with a planning application could address the following issues;
Energy and CO2 Emissions (Capital and Operational)
Materials to be used (BREEAM ratings etc)
Quite Often a Sustainability Statement will have to outline the projects adherence to a number of legislative schemes, optional schemes and perhaps a 10%, 15% or 20% saving / renewables.
There are numerous ways in which these targets can be met, it is worth engaging a professional to make suggestions on the method for doing this as it can save you £1000s, we are well aware of the cost benefit of various methods, and can make a cost effective suggestion for your project.
Based on your projects operational power consumption, and emissions resulting from that power consumption it is often required to supply details of measures to reduce emissions by a %.
Energy Saving Features such as insulation above statutory minimums do count towards such reduction but saving are hard to calculate without time consuming calculations which consider the entire building envelope.
Renewables such as Solar are a popular choice. Combined Heat and Power (CHP) is also popular particularly in larger projects with the right kind of power heat ratio demand.
Other scheme such as life times home and homes for life may also be included within the report.
View an example sustainability report.