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NSW Department of Planning, Industry and Environment
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The NSW Household Projections User Guide is for people using NSW household projection data ;to understand how the projections are prepared and how to use them. It answers common questions about projection data, the methods used to prepare the household projections, their interpretation and use.

 

Published: September 2016

A household is two or more people who share a dwelling (house, apartment, townhouse, caravan, etc.) and share food and cooking facilities, and other essentials.  Lone person households are where one person is responsible for their own food and other essentials.  

Household projections show the number of households that would form if demographic trends continue and if assumptions about living arrangements are realised over the projection period.  

Household projections show the future number and type of households living in private dwellings.  Private dwellings are self-contained accommodation such as houses, apartments, mobile homes or other ‘substantial’ structures.  It does not include accommodation such as boarding houses, nursing homes or prisons.  

The household projections also include the implied dwelling demand for those households.  This is the likely number of private dwellings needed to accommodate future population-driven demand.

NSW household projections are produced by the Department.

 

Meet the team who prepare the NSW household projections.

NSW household projections are updated when NSW population projections are updated every two to three years.  The 2016 NSW household projections are based off the 2016 NSW population projections.

The household projections give an indication of how many households the projected population is likely to form, and the types of households. Household projections inform estimates of likely housing demand.  They show the kinds of housing, infrastructure and services different households may need.


The NSW Household Projections are prepared using the sequential propensity household projection model. It is based on the NSW population projections and shows the likely number of households and types of households that will form based on the projected population and assumptions about living arrangements.

The NSW Household Projections are prepared using the sequential propensity household projection model. It is based on the NSW population projections and shows the likely number of households and types of households that will form based on the projected population and assumptions about living arrangements

The method begins with already calculated population projections by age. Data on current living arrangements of the NSW population, that is whether a person lives alone or with other people and the relationship between those people, are also needed (see figure below). First of all, the population is separated into those people who live in a private dwelling and those who live in a non-private dwelling, that is establishments which provide a communal type of accommodation (e.g. hotel, motel, prison, hospital, boarding school, staff quarters, retirement home, or hostel for the homeless).

 

The method starts with the 2016 Population Projection. Using people’s ages it works out their living arrangements. Living Arrangements are then  used to project household types.

 

The projected living arrangements are then calculated in a series of steps for the population living in private dwellings. This is arranged in a tree structure in which progressively more detailed living arrangement categories are calculated in each subsequent step. For example, children are divided into those under and over the age of 15 years and then whether they live with both parents or in a single-parent family. When all the different living arrangement groups are separated and applied to the population projections, they are converted into projected numbers of households.

 

The sequential propensity household projection model projects the following household types:

Family households:

  • Couple with child(ren) household
  • Single parent household
  • Couple only household
  • Multiple-family household (e.g. three generations)
  • Other family household (e.g. siblings)

 

Non-family households:

  • Lone person household
  • Group households

 

The strength of this model is that it is responds to changing population age structures. For example, as population ageing progresses over time, more lone person and couple only households are projected.

 

The first step it to assume one projected household occupies one dwelling.  An additional adjustment is made to account for a per cent of all dwellings being unoccupied (e.g. new occupants have yet to move in, the dwelling is used as a second residence or it is a holiday home).  This added per cent gives the final number to the projected number of implied dwellings.  It is the reason the projected number of implied dwellings is higher than the projected number of households.  

Implied dwelling demand projections are not dwelling targets or a projection of future dwelling construction. The dwelling projections make no assumptions about the type of dwellings that projected households may live in.  The projections do not make an assessment of the likelihood of the projected dwellings being available during the projection timeframe.


The 2016 NSW population projections give the starting point for the 2016 NSW household projections.  The projected age profiles from the population projections are the key determinant of projected households.

The 2011 Census is used to work out the likelihood of a person living in a particular type of household by age. 

The jump-off number of households and dwellings are for 2011.  They are based on Census counts of households and dwellings and extra adjustments are made to estimate the household and dwelling undercount.  

The household projections assume that the level of Census population undercount (what per cent of people were missed on Census night) applies to households and dwellings.  This means the 2011 jump-off number of households and dwellings in the projections is higher than the reported number of households and dwellings in Census tables.  

The household projections has two lots of assumptions. First, living arrangement assumptions for each age group are needed. These are applied to the population to project how many people will be in each type of living arrangement. Second, assumptions are made about the proportion of dwellings that are unoccupied to calculate the implied dwelling demand projections. 

The assumptions used in the NSW Household Projections are set by the Department. The assumptions are discussed with and endorsed by the Population Projections Group, a whole-of-government technical and advisory body.

The likelihood of a person living in a particular type of household is based on observations from the 2011 Census about the number of people in each living arrangement by age. This is applied to the population projections to give the per cent of people at each age living in the different living arrangements. With the exception of adult children living at home with their parent(s), the likelihood of living in different living arrangements are held constant over the projection horizon. 

The NSW Household Projections assume that the proportion of adult children living at home with their parents will increase slightly from 2011 to 2036.  This reflects a trend of adult children living at home longer because of increased participation in tertiary education and growing costs associated with home ownership.  

These household projections do not make any assumptions about average household size.  Average household size is only calculated once the household projections are completed.  

It is assumed that each projected household will need one dwelling.  An adjustment is also made for additional dwellings that may be unoccupied, assuming that the rate of unoccupied dwellings from the 2011 Census remains constant over the projection horizon.  
  
There are no assumptions about the type of housing that the projected households will live in, or assessment of the likelihood of the projected dwellings being available during the span of the projection horizon.


The population projections that are the base of the household projections may have errors in it.  These can arise if there are sudden changes in demographic behaviour because of political, economic or environmental events.  Errors can also arise when the data and information used to inform the assumptions changes or is of substandard quality.  

The likelihood of living in different living arrangements may also change.  There could be changes in behaviour such as children staying at home longer than expected, or more people forming group households of unrelated persons.  

A key reason the projections are reviewed on a regular basis is to respond to events or data issues that affect the population and household projection assumptions.


The 2016 projections show more household growth for NSW compared to the 2014 projections. The revised population projections mean NSW is likely to have 3.9 million households by 2036. This is 81,450 more households than seen in the 2014 projections.  This means an implied dwelling demand of 4.3 million dwellings by 2036 across the state. This is 86,550 more dwellings than previously projected.  

The 2016 projections have the same household profiles as the 2014 projections. Couples with children will be the most common single household type, and households without children will continue to outnumber households with children living in them.

A household is two or more people who share a housing unit and share food and cooking facilities, and other essentials for living.  Lone person households are where one person is responsible for their own food and other essentials without combining with another person.  Housing refers to the structure or dwelling that a household lives in.  This includes stand-alone houses, townhouses, units and apartments.  Dwellings in the NSW Household Projections do not include non-private dwellings such as boarding houses, nursing homes, prisons, etc.

The projection of implied dwelling demand shows how many dwellings are likely to be needed to accommodate the projected population and the households likely to form.  It is a demand-driven estimate.  The housing supply forecasts show the number of dwellings that are likely to be built based on current dwelling approvals and construction activity, as well as current stocks of zoned land and market take-up rates in the medium to longer terms.  These are supply-driven estimates.  The two lots of projections give different information to inform planning.  For example, they can show where demand is greater than forecast supply.

The data files that have been published for download have been summarised at the following geographic levels:

  • NSW state summary
  • Projection summaries
    • Sydney Metropolitan
    • Regional NSW
    • NSW Planning Regions
  • Local government areas
    • Boundaries as 1 July 2016

 

Data are not available from the ABS to inform household projections for Parramatta, Cumberland and The Hills Councils using the new Council boundaries announced 12 May 2016. For more information these Councils can contact the Demography Unit at population@planning.nsw.gov.au.

You can download data for NSW and all local government areas (LGAs) in a Microsoft Excel flat file format that allows users to sort and group data here

You can download data for each individual LGA, formatted in a ready to print format here.  

The projections are for 25 years from 2011 to 2036. 

The following conventions regarding dates are used in these projections.

 

‘The number of households in 2011’ is shorthand for the number of households at 30 June 2011.

 

‘Household change in 2011-16’ refers to household change over the five year period starting 1 July 2011 and ending 30 June 2016.

The first step is to understand why the projections are different.  Differences between household projections can be due to the following factors:

1. Base year: The 2016 NSW projections have a base year of 2011 and include published data available to 2014 (or 2015 where available). Projections with a different base year are likely to have a different result.   

2. Method: Different methods produce different results. The NSW household projections use a sequential propensity household projection method. This can produce different results to a model that is based on household or dwelling trend lines. The NSW household projections also use a multi-regional model so that all LGAs are constrained to a state total.  This can produce different results to a model that is for one area or region alone. 

3. Assumptions: Different living arrangement assumptions can lead to different results in terms of number of projected households and implied dwelling demand.  

4. Population data: The population projections form the base of the household projections.  Different population data will lead to different outputs.  

The second step is to identify which projections are the best fit for purpose. The 2016 NSW household projections are not available at the suburb level, for example, so a different data source may be needed.  

Projected household and implied dwelling demand growth rates are calculated after the projection modelling is completed. It shows the cumulative impact of the assumptions related to living arrangements for the projected population over time. 

The strength of the household projections is that it reflects changing age structures over time.  It is important to look at projected household types alongside projected population age profiles.  In places where there is a large proportion of the population in the older ages there will be more lone person and couple only households.  

Department of Planning and Environment (2016), 2016 New South Wales State and Local Government Area population and household projections. Sydney, NSW. 

Household and housing numbers are rounded to the nearest 50. Publishing unrounded numbers give a false sense of accuracy to the projections. Projections are developed to give an indication, rather than an exact number, of the types of household we may see in the future.

Projections are provided for the following household types:

  • Couple only household
  • Lone person household
  • Couple with child/children household
  • Single parent with child/children household
  • Multi-family household 
  • Other family household 
  • Group household

All figures published in the NSW projections are rounded to the nearest 50. Raw numbers from the projection model are rounded to the nearest multiple of 50. This applies to the published projected household by household types, and for the total number of households. 

For all households, the raw numbers for sub-categories (such as household types) are added together to give the raw total number of households. These raw totals are then rounded to the nearest 50 and published in the projections. 

For example: 


We calculate the total number of households by sum of the raw numbers for three areas with counts of 476, 302, and 180. These raw figures sum to the raw total of 958, which is 950 when rounded to the nearest 50. We would publish 950 as the total for the sum of the three areas. On the other hand, the numbers for the areas would be published as 500, 300, and 200 when rounded to the nearest 50. These rounded figures sum to 1,000 and is different to the published total of 950.

Page last updated: 11/06/2019