The marginal cost of September sittings is relatively low as most operating costs are fixed for the year as a whole and are unaffected by the number and distribution of sitting days. Marginal costs of a two week sitting in September are estimated to be around £200,000, mainly arising from the production of business papers and Hansard. If the September sitting is an alternative to sitting on more days at other times, the overall impact across the year will be less.
Major projects being undertaken this summer, notably the mechanical and electrical works in the Palace of Westminster including the corridor works on the Principal Floor, were planned around the known sitting dates. It is not possible, therefore, to accurately quantify any additional project costs arising from the House sitting in September 2012.