These are the findings of new research from property consultant FPDSavills which also finds that the number of units completed in that time has also fallen, this time by 8%. Although developers are increasing densities on sites - either by design or because of planning demands - this has not translated into a boost in units built.<p></p><p> &amp;“Ironically the welcome new move from greenfield development to brownfield may have worsened the supply shortage in the short to medium term,&amp;” says Yolande Barnes, head of research at FPDSavills. She says this is because urban sites are more complex and take longer to steer through planning.</p><p> The research finds that even with the current low levels of building, developers hold just 2.5 years of developable plots - undermining suggestions that they are deliberately holding back developable land to boost prices. An upturn in building rates could lead to a blockage in the development pipeline.</p><p> &amp;“If housing shortages are to be eased, more land must be made available in the places it is needed,&amp;” says Barnes, and planning permission given quickly. &amp;“The conventional approach to land release and development will not work,&amp;” she added. &amp;“A new and more cooperative approach is needed to …