Background Notes

Metered Electricity Consumption

Introduction

This release contains quarterly metered electricity consumption data for 2015 to 2020. The data were received from the Electricity Supply Board (ESB Networks) for all connections to the mains electricity network.

Consumption unit

The data are expressed in kilowatt hours (kWh) or gigawatt hours (GWh). A kilowatt hour is a unit of energy equivalent to one kilowatt of power sustained over an hour. A gigawatt hour is equivalent to one million kWh. Kilowatt hours are used for presenting median figures and gigawatt hours for presenting aggregates.

County

The CSO extracted the county and Dublin postal district from the address details provided by ESB Networks. The CSO matched the address with other data sources such as the SEAI Building Energy Ratings and GeoDirectory to assign a county or Dublin postal district to any records that were not coded using the ESB address details. In a small number of cases it was not possible to assign a county to a meter. A small number of very large customers have not been classified by county for confidentiality reasons.

Dublin postal district

The CSO extracted the Dublin postal district from the address files. Where an Eircode was available, the postal district could be extracted directly from the routing key. In other cases, there was uncertainty between some postal districts being derived from the street name. Hence the coding at this level should be regarded as only broadly correct.

Coverage

The data provided to the CSO covered all customers connected to the mains electricity network. This includes both non-residential and residential customers. Locations such as bus shelters and street lighting were included. 

Data quality

The meter readings data were converted to quarterly consumption estimates by ESB Networks. Meter readings can be actual or estimated. Actual readings can be from a meter reader or from the customer. The data file provided to the CSO did not provide information on whether the consumption in a period was based on an actual or estimated reading. The total electricity consumption figures are broadly consistent with the Commission for Regulation of Utilities reports and with the Sustainable Energy Authority of Ireland energy balances.

Revisions

Data for all years are subject to revision. The most likely revisions will arise from an adjustment to move non-domestic customers from Distribution Use of System (DUoS) groups 1 and 2 to a non-residential DUoS group. Amendments could also arise from correcting errors in the county coding.

Data source

The CSO received the administrative microdata under Section 30 of the Statistics Act, 1993. The CSO received quarterly data for 2015-2020 for all metered electricity customers. Daily data were received for a small number of large customers.

Median consumption

The median can be regarded as typical usage as it is not influenced by outliers in the same way that the mean or average is. The annual median is calculated independently of the quarterly medians, e.g. in Table 5A.

Release frequency

This release will be published on an annual basis.

Tariff group

The data received by the CSO were classified by tariff category (DUoS). DG1 is urban domestic and DG2 is rural domestic. However, small commercial customers (newsagents, farms, etc.) are sometimes included in these categories. Hence the total consumption by the residential sector is an over-estimate. The Large Customers category is a combination of DUoS groups DG8, DG9, DG10 and TCON.

The DUoS is determined by factors such as the type of use, maximum import capacity (MIC), and the nature of the connecting network. A domestic customer premises is defined as any premises whose main purpose is that of a single residence and where the connection agreement is with a private individual with an MIC up to 29,000 voltamperes.

Urban domestic connections are defined as domestic connections that are fed from three-phase overhead or underground low voltage network. Rural domestic connections are defined as domestic connections that are fed from single-phase overhead network. A non-domestic customer premises is defined as any premises whose main purpose is that of carrying out a business.

Public lighting connections with loads up to 2,000 voltampere are unmetered. Connections to street kiosks, bus shelters, etc. are unmetered up to the 2kVA load.

Comparison with gas consumption

A similar statistical release for networked gas consumption is published by the CSO on an annual basis using a similar analysis structure. Gas consumption is more seasonal as it is used more for main space heating. Hence a comparison of consumption in January to March with July to September shows more seasonality for gas than for electricity.

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