Given development under NPF4 is dependent on allocated sites and heavily focused on brownfield, it is important to understand how much housing supply these sites can deliver. Unfortunately, the evidence of recent years is mixed, and suggests that development on brownfield in particular is becoming more challenging.

Overall, between 2020 and H1 2025, homes granted consent on brownfield sites only accounted for less than half (45%) of total supply, and those on allocated sites barely over a third (34%). That greenfield and unallocated sites make up over half of housing supply over the past five years should raise significant concerns. An approach to planning that relies solely on allocations and brownfield will not provide adequate sources of housing supply.

More worrying still is that headline trends for housing supply are also heading in the wrong direction. Since mid-2020, the number of homes being granted full planning consent in Scotland has more than halved, falling by 56% on an annualised basis.

The number of homes being granted consent on allocated sites have seen a smaller fall than overall volumes, as NPF4 limits consents to these sites. These tend to be large, strategic sites central to LDPs, so a drop of over a quarter (26%) since in five years is still cause for serious concern. Ironically, the decline in wider consents due to NPF4 Policy 16(f) has caused allocated sites to become a more important part of housing supply. Homes on allocations contributed around 65% of consented homes in the first six months of 2025, compared to one in three (33%) on average between 2020 and 2024.

This illustrates the important contribution of windfall housing sites to supply, which is currently closed off by Policy 16(f). A policy direction that excludes non-allocated sites places more and more pressure on the handful of sites that are allocated, leaving housing supply more vulnerable to delay or shocks should development challenges prevent a site from progressing.

At the same time, the focus on brownfield raises questions over how many new homes these sites can deliver. Brownfield sites have seen a much sharper contraction in the number of homes being granted consents, with less than a third of the number being permitted five years ago. Relying on brownfield also presents a risk, due to the typically higher density and prices required to make such schemes viable alongside higher build costs and longer construction periods (discussed below). Combined with a lack of planning permissions, these conditions risk deterring many developers.

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