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Background Notes

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These notes provide general information on the 2011 and 2016 Censuses of Population in the context of this report. For more detailed information on the Census, please go to the CSO population web page

This report is an analysis of the 2011 and 2016 Censuses of Population from an environmental perspective. This report should be used to examine census data from an environment context such as what kind of differences are there between households that use different fuels for central heating. Another example perspective is to examine changes between both censuses e.g. what are the characteristics of households that were using solid fuel central heating in 2011 but switched to other fuels such as oil, natural gas, or electricity in 2016. It should not be used for census figures as this report excludes some persons and some households that are included in the official census reports.

Census night

The 2011 Census of Population was taken on the night of Sunday, 10 April 2011, in accordance with the Statistics Act 1993 and the Statistics (Census of Population) Order 2010 (S.I. No. 207 of 2010).

The 2016 Census of Population was taken on the night of Sunday, 24 April 2016, in accordance with the Statistics Act 1993 and the Statistics (Census of Population) Order 2015 (S.I. No. 445 of 2015).

Coverage of the Census

The census figures relate to the de facto population i.e. the population recorded for each area represents the total of all persons present within its boundaries on census night together with all persons who arrived in that area on the following morning not having been enumerated elsewhere. Persons on board ships in port are included with the population of adjacent areas. The figures include visitors present in a household on Census night as well as those in residence. Usual residents who were temporarily absent from the household on Census night are excluded from the figures for that household.

Census 2016 questionnaire

A copy of the Census 2016 English household form can be downloaded at the link below. The form shows the full list of response categories for each census question. In this report, these responses have been aggregated into a small number of categories e.g. summary age groups and nationality (Irish or Foreign).

Occupied private households

This report only includes private households where there was at least one person present on Census night.

A private household comprises either one person living alone or a group of people (not necessarily related) living at the same address with common housekeeping arrangements - that is, sharing at least one meal a day or sharing a living room or sitting room.

A permanent private household is a private household occupying a permanent dwelling such as a house, flat or bed-sit. A temporary private household is a private household occupying a caravan, mobile home or other temporary dwelling.

Household reference person

The householder or any adult member of the household present on Census night could complete the form. The first person listed on the census form was classified by the CSO as the household reference person. Other persons were defined in terms of their relationship to the first person e.g. husband or wife, son or daughter, etc.

Many of the tables presented in this report use the details provided for the household reference person such as their general health or present principal status. Some tables make a distinction between whether the reference person was the same in 2011 and in 2016. This was defined as having the same date of birth and sex. While this distinction is regarded as useful, it should be used with caution as the household could put any adult member present on Census night as the reference person.

Occupants in 2011 and 2016

Some analysis tables in this report distinguish between whether there is a link between the occupants in 2011 and in 2016. A link has been defined as there being at least one person with the same sex and date of birth present on both Census nights. The purpose of this variable is to allow users to examine whether environment-related changes are more likely to occur if the house has been sold e.g. has there been a change from solid fuel central heating.

Place of work, school or college

The category student covers persons aged 5 to 14 and persons aged 15 and over who indicated they were students in the present principal status question.

The location of the place of work, school or college was coded for each person based on the full address of place of work or study provided by each person. The employer/school name and address was matched against addresses on the An Post GeoDirectory to facilitate analyses such as commuting patterns.

Geographical coordinates of household

Each dwelling was linked to geographical coordinates. In the case of 98% of dwellings on the Census 2016 geography dataset, this linkage was achieved through using the national address database as the basis to conduct the enumeration of dwellings. The remaining 2% of dwellings enumerated was retrospectively digitised by census staff according to the location marked by enumerators on paper maps during census fieldwork activities. These coordinates enable indicators such as distance from the coastline or river basin district to be calculated.

Counties and Dublin postal districts

In Dublin, the four local authority areas are identified separately i.e. Dublin City and the three administrative counties of South Dublin, Fingal and DĂșn Laoghaire-Rathdown. Section 9 of the Local Government Reform Act 2014 provided for the amalgamation of the city and county councils in Limerick, Waterford, and North and South Tipperary County Councils. To facilitate comparison between 2011 and 2016, these changes have been incorporated into the 2011 tables also.

The Eircode was used to extract the Dublin postal district. There are substantial environment-relevant differences between Dublin postal districts such as period of construction, type of building, and type of central heating. A separate CSO statistical release on Building Energy Ratings is broken down by Dublin postal district. The BER release can be combined with this report to establish what proportion of households have had a BER audit or to weight the BER data to the full postal district level.

Dublin postal districts are mostly located in Dublin City but they can also be located in the other Dublin administrative counties. The county coding was done by Census of Population whereas the Eircode was independently sourced by Census.

Electoral Divisions

Electoral Divisions (EDs) are the smallest legally defined administrative areas in the State. There are 3,440 legally defined EDs in the State. For disclosure reasons, 32 EDs with a low population have been amalgamated with neighbouring EDs. This administrative area unit is not used in this report.

Settlements, Urban and Rural Areas

A settlement was defined as:

  • A cluster of 50 or more occupied dwellings
  • A maximum distance of 100 metres between any dwelling and the building closest to it
  • Evidence of an urban centre, (e.g. shop, school)

An existing settlement could be extended from the 2011 census if there were newly created estates or dwellings within 100 metres of the 2011 settlement boundary.

An urban area is a settlement with 1,500 people or more. Rural areas are defined as the population outside urban settlements and thus include towns with less than 1,500 persons.

Islands off the Coast

Islands as a group are distinguished in this report from households located on the mainland.

Household tenure

Household tenure was derived based on whether the household owned or rented their accommodation.

Household composition

The determination of household and family composition is based on responses to the question on the census form dealing with relationships within the household.

Mobility difficulty

This was defined as persons who indicated that they had a long-lasting condition or difficulty which was defined as lasting for six months or more or regularly re-occurring.

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