Land and Housing Supply Indicators methodology

The basic unit underpinning these counts are land parcels, which are the smallest units of land that can be bought and sold. For most purposes, these are the basic unit for land administration and development.

Land parcels are recorded by states and territories in land administration systems called cadastres. These capture boundaries, ownership, rights, and restrictions that apply to land parcels. Cadastres can also be represented spatially as maps that show the boundaries of all the registered land parcels across an area. These cadastral maps are the data source for land parcel information used to produce these indicators.

Land parcels may only have one title of ownership issued, but in certain cases where there is shared ownership for common property, there may be multiple titles. In these situations the parcel is further divided through a strata plan into private units and common property. These strata parcels are often captured in cadastral maps, however counts presented in this publication only reflect the underlying land parcels they sit on top of.

In some states and territories, parcels are created for public infrastructure like roads. These have been excluded as an input into the counts presented in this publication.

Building approvals are issued as part of the normal administrative building approval process. The ABS collects these primarily from local government authorities, but also from other principal certifying authorities including commonwealth, state, and semi-government authorities.

The approvals used in this publication cover all approved residential building work valued at $10, 000 or more, where new dwellings will be constructed as part of the development. It excludes approvals for dwellings that will be attached to existing structures, or converted from a non-residential building to residential, known as "Alterations and additions" or "Conversions" respectively.

Building approvals are provided with address information which can be used to identify the location of the building work in most cases. This has been utilised for this publication to associate building work with a building site and area and local zoning information.

The counts of land parcels presented in this publication are given for a reference period at March 2022 and provided for areas in the geographic scope outlined below. The counts include all lot parcels (excluding strata/stratum/road parcels) that are titled (have a title issued) and have an area greater than 50 square metres.

The dwellings approved cover the 2021 calendar year for all states and territories except South Australia, where only approvals from June to December 2021 are included. This reflects the introduction of the state-wide Planning and Design Code in South Australia in March 2021. Dwellings approved are also provided only for the areas outlined in the geographic scope below, and capture all dwellings approved as part of new residential work.

The geographic areas included represent the 20 largest SUA regions (from ASGS 2016) by population at 2020 with the addition of Melton, recognised as a key growth area for Melbourne. The local government areas (2021 edition) overlapping these SUAs are also represented in the data, with the following exceptions:

• Toowoomba, Queensland - excluded from lot counts and dwelling counts as no current zoning information is available
• Brighton, Tasmania - excluded from dwelling counts as zoning information available does not align with the timing of building approvals
• Clarence, Tasmania - excluded from dwelling counts as zoning information available does not align with the timing of building approvals
• Glenorchy, Tasmania - excluded from dwelling counts as zoning information available does not align with the timing of building approvals.

Data is only reported for major urban areas since land supply and regulation are not likely to be a significant factor for housing supply outside of these. For capital cities, significant urban areas are used rather than greater capital city statistical area (GCCSA) regions since they better approximate the urban footprint of cities. For further information on these boundaries, see Australian Statistical Geography Standard, Edition 3

Zoning is the basic tool used to apply and communicate regulation in all states and territories. Each state has its own range of zones, resulting in significant variation nationally. To produce nationally consistent indicators and enable comparison, standardisation of these is needed.

The classification for zoning used in this publication provides a way to standardise the zones represented in the data. Consideration was given to the different aspects of zoning that could be the basis for classification, including:

• Permitted/promoted use
• Generality (how many different uses)
• Density (of allowed uses)
• Degree of discretion

The first of these is the basis for the classification used in this publication, noting that there are opportunities to capture the other features of zoning through extensions in the future.

The classification developed for this publication identifies ten broad use classes and assigns each zone in the data to whichever of these is identified as preferred in the relevant planning scheme. Where this cannot be easily determined, assessment is based on evaluation of the list of uses listed as permitted with or without assessment.

The use classes are intended to reflect a complete but mutually exclusive set of possible uses for land. Determining these took into account state/territory approaches to grouping zones in their planning system, as well as the full range of unique zones covering the in-scope lots in the data.

The use classes along with a brief description and some examples of zones classified by them are provided below.

Land parcel size is reported in this publication in square metre ranges. This allows the continuous range of parcel sizes to be represented in only a few distinct categories and grouped for counting.

The ranges implemented were developed to have clear implications for future development possibilities. 200 square metres was determined as a lower end for most subdivision scenarios based on the distribution of floor area for new dwellings, and based on this 200 square metre ranges are used up to 1000 square metres. 1000 to 10, 000, and 10, 000+ square metre ranges are also included to capture extremely large parcels at the upper end of the distribution. The resulting ranges are given below, with an approximate indication of how many parcels large enough to accommodate a dwelling could be produced through subdivision.

These counts are produced using three main data sources.

Dwelling counts are derived from building approvals collected by the ABS for publication in Building Approvals, Australia. For further information on the collection and scope of these, see Building Approvals, Australia methodology.

Land parcel data used and associated planning data are provided by Geoscape, subject to the copyright notice and disclaimer below.

Administrative Boundaries (comprised of Localities, Local Government Areas (LGAs), Wards, Australian Bureau of Statistics (ABS) Boundaries, Electoral Boundaries, State Boundaries, and Town Points), Airports, CadLite, Cadastre, Features of Interest, Geoscape Address Data obtained via Geoscape APIs, G-NAF, G-NAF Live, Greenspace, Hydrology, Land Tenure, Postcode Boundaries, Property, Rail, and Transport and Topography © Geoscape Australia. These datasets are created using a range of source data including:

• Source data © Australian Capital Territory (Environment, Planning and Sustainable Development Directorate);
• Source data © Commonwealth of Australia (including the Department of Industry, Science, Energy and Resources, Geoscience Australia, the Australian Electoral Commission and the Australian Bureau of Statistics (see note below));
• Source data © New South Wales Crown (Spatial Services, Department of Customer Service);
• Source data © Northern Territory Government (Department of Infrastructure, Planning and Logistics);
• Source data © State of Queensland (Department of Resources);
• Source data © Government of South Australia (Department for Environment and Water);
• Source data © Government of Tasmania (Department of Primary Industries, Parks, Water and Environment);
• Source data © State of Victoria (Department of Environment, Land, Water and Planning); and
• Source data © Western Australian Land Information Authority (Landgate).

Geoscape Planning © Geoscape Australia. Geoscape Planning is created using a range of source data including:

• Source data © Australian Capital Territory (Environment, Planning and Sustainable Development Directorate);
• Source data © Commonwealth of Australia (including the Department of Industry, Science, Energy and Resources, Geoscience Australia, the Australian Electoral Commission and the Australian Bureau of Statistics (see note below));
• Source data © New South Wales Crown (Spatial Services, Department of Customer Services);
• Source data © Northern Territory Government (Department of Infrastructure, Planning and Logistics);
• Source data © State of Queensland (Department of Resources);
• Source data © Government of South Australia (Department for Environment and Water);
• Source data © Government of Tasmania (Department of Primary Industries, Parks, Water and Environment);
• Source data © State of Victoria (Department of Environment, Land, Water and Planning); and
• Source data © Western Australian Land Information Authority (Landgate).
• Statewide planning schemes information 2009-2010 – Brisbane Central Office © State of Queensland (Department of State Development, Manufacturing, Infrastructure and Planning) licensed under the Creative Commons Attribution 3.0 Australia Licence (updated data available at http://qldspatial.information.qld.gov.au/catalogue//) (open data);
• Brisbane City Plan 2014 Zoning overlay Brisbane City Plan 2014 Zoning overlay © Brisbane City Council licensed under the Creative Commons Attribution 4.0 International Licence (open data);
• City Plan Zone licensed by City of Gold Coast under the Creative Commons Attribution 3.0 Australia Licence (open data);
• Logan Planning Scheme Dec 2015 licensed by Logan City Council under the Creative Commons Attribution 3.0 Australia Licence (open data);
• MBRC Planning Scheme Zones (June 2016) licensed by Moreton Bay Regional Council under the Creative Commons Attribution 4.0 International Licence (open data);
• Source data © Noosa Shire Council; 
• Source data © Redland City Council.
• Tasmanian Interim Planning Scheme Zone Boundaries and Tasmanian Interim Planning Scheme Zoning from theLIST © State of Tasmania  licensed under the Creative Commons Attribution 3.0 Australia Licence (open data);
• Tasmanian Planning Scheme Zones from theLIST © State of Tasmania licensed under the Creative Commons Attribution 3.0 Australia Licence (open data);
• Source data © Government of Western Australia (Department of Planning, Lands and Heritage);
• Source data © Burdekin Shire Council;
• Source data © Fraser Coast Regional Council;
• Source data © Lockyer Valley Regional Council;
• Source data © Mareeba Shire Council;
• Source data © Cairns Regional Council;
• Source data © Bundaberg Regional Council;
• Source data © Ipswich City Council;
• Zone layer of the Zone Maps of the Sunshine Coast Planning Scheme 2014 licensed by Sunshine Coast Council under the Creative Commons Attribution 3.0 Australia Licence (open data); and
• TCC City Planning Scheme – Zoning licensed by Townsville City Council under the Creative Commons Attribution 4.0 International Licence (open data).

Geoscape Australia endeavours to ensure that its products and services are accurate and complete by using source data primarily from Australia’s federal, state and territory governments and other reputable sources. However, Geoscape products and services are provided ‘as is’ and neither Geoscape Australia, nor its distributors, nor Australia’s federal, state and territory governments, nor any other providers of source data make any representations or provide any warranties (express or implied) about the accuracy or completeness of Geoscape products or services, their fitness for any particular purpose or that they are without errors or faults. Geoscape Australia, its distributors, Australia’s federal, state and territory governments and any other providers of source data have no liability (including liability in negligence) for any losses suffered (including any indirect losses, loss of profits or data and any other consequential loss) or expenses incurred arising from use of Geoscape products and services for any particular purpose, Geoscape products and services being inaccurate or incomplete in any way for any reason or any errors or faults in Geoscape products and services, even if Geoscape Australia, its distributors, Australia’s federal, state and territory governments or any other providers of source data have been advised of the possibility of such losses or expenses.

Information associated with land parcels is used to scope and classify them into groups according to their:

• Geography
• Zoning
• Size

The geographic areas that the land parcels fit within determine whether they conform to the geographic scope for the publication. Parcels are then filtered to keep only lot parcels (i.e. non-strata or road) that are titled.

Following this, the detailed zoning information is compared against a concordance table matching zones to the zoning classification used in this publication. Where there is no match to the classification, processing staff assign a classification to the zone using a set of guidelines so that every zone represented in the data has a mapping to the classification.

Next the area of the parcels is classified based on the range it falls into. These characteristics are used to group the in-scope parcels for aggregation to produce final counts.

In a small number of cases, zoning information cannot be linked to parcels. This is the result of ongoing changes to planning schemes and the cadastre, as well as minor errors in the process to spatially link the two. For these cases, we apply a simple imputation model to ensure all in-scope land parcels are represented in the counts provided. This model captures the distribution of zone types (where known) within geographic subgroups, and weights the counts to ensure the same distribution holds pre and post-imputation.

Finally, the parcel-record level data is aggregated by geographic unit, type of zoning, and size ranges for publication.

The counts of approved dwellings reported in this publication derive from the same building approvals used to produce Building Approvals, Australia with additional processing to associate zoning and determine the area per dwelling from parcel size. The dwelling counts in this publication align with the April 2022 edition of Building Approvals, Australia.

Building approvals are provided to the ABS with address information. This enables the ABS to spatially locate addresses and assign them geo-coordinates (longitude and latitude) and geographic regions for aggregation and publication.

Pre-processing of address information on approvals is first carried out to maximise the proportion that will be assigned geo-coordinates through address coding. The addresses are then coded and geo-coordinates are assigned. In a small number of cases no match is able to be made. This can result from:

• Incomplete or inaccurate address information
• Non-standard addressing system
• New addresses not yet appearing on the address index

For these approvals, zoning and area per dwelling has been determined at a later stage through an imputation model.

The approvals with valid geo-coordinates are next spatialised in a Geographic Information System (GIS) and intersected with land parcel and zoning spatial layers to identify the building site and zoning for the building work. A set of decision rules are applied at this stage to determine whether the intersect scenarios are valid. These take into account factors including:

• Whether the building approval geo-coordinates intersect a valid parcel
• The number of dwellings associated with the approval
• Whether the building approval address appears to refer to pre or post-subdivision land parcel

Where these rules determine a valid intersect, zoning and site area are associated with the approval.

This dataset is then further processed to filter any outliers with respect to the area per dwelling. Most outliers arise from misalignment of the building approval and the land parcel formation process (either subdivision or amalgamation of parcels), resulting in area per dwelling estimates that are either significantly larger or smaller than the accurate value. These are determined by rules referencing the different scenarios that may present.

In some situations where the site area obtained through spatial intersection is not accurate, the data is supplemented with the site area supplied with the building approval. The accuracy of this is also determined by a set of rules to filter any extreme outlier values. Some desktop canvassing of approval sites was also undertaken for significant approvals (either large buildings or large numbers of dwellings) and measured areas assigned manually. These areas are used to determine the area per dwelling by dividing the site area by the number of new dwellings on the approval.

Finally the approval records that are missing zoning information or area per dwelling have these values imputed to ensure all dwellings approved are represented in the final counts. The imputation model applied looks to ensure the distributions across zoning and area per dwelling present in the pre-imputed data remain the same after imputation. To accomplish this, distributions are calculated for sub-samples defined by key variables, and the distribution is used to randomly assign a zone type and area per dwelling range to records that are missing this information.

For zone type, the imputation starts by looking at sub-sample determined by local government area and Functional Classification of Buildings (FCB) code. For area per dwelling, it starts by looking at sub-samples across local government area, FCB and zone type. In cases where sample size within these groups are too small, less strict groupings are taken until all remaining records are imputed.

The last step sees the dwellings aggregated in counts according to their geography, FCB, zone type, and area per dwelling for publication outputs.