The revised NPPF (specifically, paragraph 63 of the July 2018 Revised NPPF) states that to support the re-use of brownfield land, where vacant buildings are being reused or redeveloped, any affordable housing contribution due should be reduced by a proportionate amount. The NPPF goes on to state that the reduction should be equivalent to the existing gross floorspace of the existing buildings.
Therefore, credit will be given for floorspace equivalent to any vacant built floorspace (i.e. excluding temporary structures such as sheds) which is reused or redeveloped, before affordable housing is sought at the rate appropriate to the net increase in dwellings for the scheme.
A site with a vacant building of 500 sq m is redeveloped for housing. The residential scheme is for 7 three bed houses each of 110 sq m and 10 two bed houses each of 80 sq m. The total floorspace (measured as Gross Internal Area in square metres) after development is 1,570 sq m. Credit is given for 500 sq m.
Therefore the starting point for policy PCS19 is to seek affordable housing on 1,070 sq m of residential development. The average size of the proposed dwellings is 92 sq m. Therefore affordable housing will be sought on (1,070 / 92 = 11.63) 12 dwellings. The net increase in dwellings across the development is more than 15, and so affordable housing provision of 30% will be sought on 12 dwellings = 3.6 (rounded to 4 units).
A site with a vacant building of 500m is redeveloped for a mixture of commercial uses and housing. The commercial element totals 300 sq m, with the residential element is for 900 sq m.
The total floorspace after development is 1,200 sq m. The appropriate credit attributed to the residential element is (500 x 900 / 1,200) is 375 sq m. The average dwelling size is 75sq m. Therefore affordable housing will be sought on (900-375 = 525 / 75 ) 7 dwellings. The net increase in dwellings across the site is 12, and so affordable housing provision of 25% will be sought on 7 dwellings = 1.75 (rounded to 2 units).
To confirm, in accordance with the NPPF this reduction will not apply to vacant buildings which have been abandoned. Similarly, if the Council considers the site has deliberately vacated for the purpose of redevelopment then it will not apply the reduction.
This will be applied in the application of adopted policy PCS13 and reflected in an updated Providing Affordable Housing note.