Westminster Infrastructure Plan: Technical Assessment (2009) WCC

Westminster Infrastructure Plan: Technical Assessment 2006– 2026Final ReportEstimating Population GrowthAt the moment the available information on housing growth at the local authority andLondon level cannot be considered as finalised. The London Housing Strategy iscurrently at Consultation Draft Stage (with the final strategy to be published towards theend of 2009). This means that local authority level dwelling targets may be revised withina year. Also, as the local authorities progress in their LDF process they may revise boththeir housing trajectory and the demographic assumptions, which would then in turnresult in changes in the overall population growth figures. It should also be noted thatdiscrepancies in population projections can be found even between the GLA and ONSestimates – adding to the complexity of establishing a reliable information base on whichto conduct the analysis.Given the lack of established population projections reflecting the recent and imminentchanges in the WCC‟s housing trajectory and regional policies, we consider it appropriateto use assumptions that, albeit less sophisticated, are transparent enough to allow a clearunderstanding of the relation between the number of dwellings that each authority is setto host and the resulting population.Accordingly, based on the projected dwellings growth as discussed and agreed withWCC we have estimated the additional population based on standard assumptions on thetenure mix, size mix and occupancy rates. The approach can be considered somewhatcrude compared with full demographic models such as the ones used for the GLA orONS projections, it also has a number of advantages.The assumptions in which our calculations are based are listed below:The tenure split is 50% private housing, with the remainder 50% further splitbetween social (70%) and intermediate (30%), as per the London Plan 2008The dwelling size split is taken from London Plan Annual Monitoring Report 4(2008), using figures from 2006/2007 LDDA standard occupancy rate of 1.9 across all tenures and size as per discussionswith WCC.With regards to residential growth, being able to relate the projected population growth tothe housing trajectory is essential for the purpose of this study. For example the mainreason is that the driver of future demand is the number of dwellings for certaininfrastructure areas (for instance electricity and gas) but the number of new residents forothers (including water and sewerage and social infrastructure).As the population resulting from our URS Infrastructure Model is consistently above theGLA estimates, it should be considered as an indicative upper constraint toWestminster‟s infrastructure needs.November 2009 Page 32