1. Quality information

Changes to definitions since 2011

There have been small changes to housing definitions since the 2011 Census, meaning some sheltered housing units were enumerated as communal establishments in 2011 but as households in 2021. Take care if you compare Census 2021 results for this topic with those from the 2011 Census, as described in Housing variables Census 2021.

Number of bedrooms

The Census 2021 question asking about the number of bedrooms allowed users to write or type any number between “1” and “99”. We believe that a small number of households accidentally entered the wrong number when completing the question. They have typically done this by entering “11” or “22” instead of “1” or “2” or similar.

The number of households recording such numbers of bedrooms remains very small, but we would encourage users to group larger numbers into categories such as 5 bedrooms and over.

Number of rooms

Census 2021 results for the number of rooms at an accommodation takes data that the Valuation Office Agency (VOA) collected. VOA number of rooms is only available at address level, while the 2011 Census recorded the number of rooms at the household level. This means that for households that live in a shared dwelling, the available number of rooms are counted for the whole dwelling in VOA, and not each individual household.

Also, VOA’s definition of a room does not include:

  • bathrooms

  • toilets

  • halls or landings

  • kitchens

  • conservatories

  • utility rooms

It does include all other rooms, for example, living rooms, studies, bedrooms, separate dining rooms and rooms that can only be used for storage. If two rooms have been converted into one they are counted as one room.

Please note that the 2011 Census question included kitchens, conservatories and utility rooms while excluding rooms that can only be used for storage.

The VOA number of rooms data from Census 2021 are not directly equivalent to the 2011 Census number of rooms estimates, because of the difference in definitions . So, it will be inappropriate to measure change in number of rooms from 2011 to 2021. Instead, use Census 2021 estimates for number of bedrooms for comparisons over time.

Occupancy rating for rooms

Census 2021 results for the number of rooms at an accommodation takes data that the Valuation Office Agency (VOA) collected. This VOA data do not typically include the kitchen in its count of rooms. Before we calculated the occupancy rating, we increased the number of rooms by one. This is to account for this difference and to make this more consistent with previous calculations for occupancy rating for rooms.

Number of cars or vans

The Census 2021 question asking about the number of cars or vans allowed users to write or type any number between “6” and “99”. We believe that a small number of households accidentally entered the wrong number when completing the question. They have typically done this by entering “66” or “77” instead of “6” or “7”, or similar.

The number of households recording such numbers of cars or vans remains very small, but we would encourage users to group larger numbers into categories such as 5 cars or vans and over.

Type of landlord

As in the 2011 Census, there is evidence of people incorrectly identifying their type of landlord between two of the response options. Those two options were “Council or local authority” and “Housing association, housing co-operative, charitable trust, registered social landlord”.

This issue is particularly clear in results for areas which have no local authority housing stock. You should add these two categories together when analysing data that use this variable.

Households of multiple occupancy (HMO) in Wales

The Census 2021 definition of households in multiple occupancy (HMO) is "a dwelling where at least three unrelated tenants rent their home from a private landlord".

The Welsh Government collects and publishes data on HMOs by local authority area in Wales, on an annual basis. In this collection, the definition differs to the Census 2021 definition. HMOs are defined as "a building or part of a building occupied by persons forming at least two households sharing at least one basic amenity". See Sections 254 to 259 of the Housing Act 2004 for more information.

For this reason, counts of HMOs published in Census 2021 and by the Welsh Government are not comparable.

Types of accommodation and movement of people experiencing homelessness

During the coronavirus (COVID-19) pandemic plans were put in place to protect rough sleepers in England and similar plans were put in place in Wales. More types of accommodation housed people who were experiencing homelessness in England and Wales and there was a movement of homeless people to different types of accommodation. Figures for those in shelters may be less than expected, because of their movement to alternative accommodation.

Figures recorded for communal establishments such as student halls and hotels may include people who are experiencing homelessness. People experiencing homelessness housed in alternative communal establishments, are not identified in the data as homeless.

Take care when analysing this data for planning or policy making. While these do not include the figures or numbers within communal establishments the official homelessness statistics in England and homelessness statistics in Wales are the most appropriate source of data to count the number of homelessness duties accepted by local authorities.

Temporary accommodation for people experiencing homelessness

Figures for “hostel or temporary accommodation for the homeless” include residents and day visitors if they have no other residence and are counted as usual residents in the population. Take care when analysing these data for planning or policy making.

Numbers of communal establishments

Census 2021 results contain adjustments for residents of communal establishments who did not respond to the census. However, we made only partial adjustments to the numbers of communal establishments to reflect the fact that some of those establishments, or residents of those establishments, might not have responded. Conversely, large establishments may have been recorded in the census as multiple establishments if the establishment had more than one address. Take care when interpreting figures on the numbers of each type of communal establishment.

Armed forces bases (second addresses)  

Armed forces personnel and defence employees are included in the census and recorded as usually resident using the standard definitions. The instructions given to personnel on how to respond to the census mean that the number of people recording a second address as type '"Armed forces base address"' is likely to be a substantial underestimate of the true number. Information on the size and characteristics of the UK armed forces population is produced by the Ministry of Defence (MOD) and available at MOD National and Official Statistics by topic.

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3. Cite this methodology

Office for National Statistics (ONS), released 5 January 2022, ONS website, methodology, Housing quality information for Census 2021.

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Contact details for this Methodology

Census customer services
census.customerservices@ons.gov.uk
Telephone: +44 1392 444972