Research and analysis

Estimate of homes subject to nutrient neutrality requirements

Published 11 September 2023

Applies to England

Introduction

On 29 August 2023 the government announced that it would be removing housing development from nutrient neutrality requirements. This was further referenced in a written ministerial statement on 4 September 2023.

This release sets out DLUHC’s estimate of the number of homes that would otherwise have been subject to nutrient neutrality requirements resulting from The Conservation of Habitats and Species Regulations 2017.

The estimate is based on past levels of housebuilding in nutrient neutrality catchment areas in England.

This is an ad-hoc analytical release and does not constitute an Official Statistics or National Statistics release.

Key points

• 7.9% of new addresses created in England from 2015/16 to 2018/19 were created in areas affected by nutrient neutrality advice
• this proportion represents an expected additional housing supply of 16,500 dwellings per year
• if housing delivery were to remain at a similar level in the years from now to 2030 this would represent over 100,000 homes in nutrient catchments

Background

Nutrient pollution is an urgent problem for our freshwater habitats and rivers, many of which are internationally important for wildlife. While the government recognises the need to protect these habitats, and is taking steps to address the underlying pollution, it is important to acknowledge the significant burden nutrient neutrality has placed on housebuilders despite the limited impact extra wastewater from residents in new developments has on waterbodies.

Under the Habitats Regulations, ‘competent authorities’ who will be the decision make for certain planning decisions must assess the environmental impact of projects and plans (such as planning applications or local plans) which affect habitats sites. Local planning authorities can only approve a project if they are sufficiently certain it will not adversely affect the integrity of the habitats site.

As a result of these regulations and case law, and the interpretation of it as a result of CJEU, Natural England issued nutrient neutrality guidance across 27 catchments and a number of local planning authorities (wholly or in part). This guidance is that as these sites are in unfavourable condition due to excess nutrient pollution, consent may only be granted if the increase in wastewater from developments will not cause additional pollution. Nutrient neutrality is one way in which developments can demonstrate there will be no harm. This involves mitigating the ‘nutrient load’ generated by the population growth due to new housing developments.

The government was concerned that this would add cost and delays to developers’ ability to proceed with housing development in those areas affected.

Technical notes

Data sources

Our best measure of overall housing supply is net additional dwellings. However, this is not available at sufficient granularity to map onto catchment boundaries since it is at local authority level. We instead use the Ordnance Survey’s AddressBase dataset that gives point locations of new addresses. This allows us to count new addresses and to know their exact location. This data is an established and robust source, already used to produce figures on the location and density of new residential development as part of the land use change statistics and is appropriate for geospatial analysis.

Nutrient advice catchment boundaries were supplied by Natural England as digital shapefiles. These boundaries are published by Natural England.

Method

The number of new dwellings estimated to be delivered within catchment areas in the absence of nutrient neutrality issues is based on data covering the period before the advice was first issued to ensure a baseline that would not have been impacted by the policy.

Since housing delivery at a local level is not smooth – in one year there may be many homes delivered and in the following year there may be none – an annual average was calculated based on three years from financial year 2015/16 to 2017/18. This period was chosen as it is the most recent that we can analyse that is unaffected by the impacts of covid-19 and is before any impact of the nutrient neutrality requirements might have been felt.

The point locations of past new residential development were compared with the nutrient catchment boundaries. The number of new addresses inside catchment boundaries was divided by the total number of new addresses in England to find the proportion of new addresses inside catchments. This proportion was then applied to historic net additional dwellings to produce a final estimate of the number of homes affected. We take this step since new address data includes a broader category of residential buildings than is counted in our best measure of housing supply, net additions. New address data includes communal accommodation, student accommodation and holiday homes which are not included in net additional dwellings. Therefore new address data would overcount housing supply compared to our net additional dwellings. We assume the proportion of new addresses created during 2015/16 to 2017/18 that were in locations that became nutrient advice catchments is the same as the proportion of net additions that were in those areas.

Results

An estimated, 7.9% of new addresses created between 2015/16 and 2017/18 were within nutrient advice catchments, equivalent to approximately 16,500 dwellings per year. This calculation is presented in Table 1.

In the remaining 6 years and 3 months before 2030, 16,500 homes per year would total over 100,000.

This figure represents the number of homes we would expect to come forward inside catchments if housebuilding continued at a similar rate to the past, which would not necessarily have been the case. It does not necessarily equal the number of homes unlocked due to a change in regulations (i.e. it does not try to take account of those houses that might have eventually come forward anyway, for example through existing credit schemes or developers delivering their own on-site mitigations). Past delivery may not be representative of future delivery due to changing market conditions or the availability of land.

Table 1. Estimated annual net additions within catchments England total

A:	Proportion of new residential addresses in England within nutrient catchments (annual average 2015-18)	7.9%
B:	England net additional dwellings (annual average 2015-18)	209,757
A×B:	Estimated annual net additional dwellings within nutrient catchments	16,500

Numbers may not sum due to rounding.