Statistics for residential energy consumption per household
“Methodology used by Statistics Norway”
Abstract
Residential energy consumption makes up a significant part of total energy consumption. Reliable information about this consumption and the underlying driving forces is a helpful tool for policy makers and others who are dealing with energy in a country. Statistics Norway has carried out periodic surveys on energy consumption and heating equipment combinations in households since the early 1990’s and has had good experiences with the methods that are used. The intention with this paper is to give a short methodological description of how the survey has been conducted. The target group for this paper is persons who are planning to conduct a similar type of survey and could benefit from other countries experiences.
For practical and cost reasons, Statistics Norway has chosen to add energy questions to the already well established survey of consumer expenditure that is conducted annually. This survey contains a lot of information that is relevant for analyses and statistics for energy consumption in households, such as household size, house type, year of construction, dwelling area and purchases of energy. By adding some questions regarding energy and types of heating equipment, we obtain a good basis for conducting analyses and estimations of the residential energy consumption and heating equipment in dwellings. However, for countries that not collect similar data in their survey of consumer expenditure, or not conduct this kind of survey at all, it is possible to use the methods in this paper as well to conduct a similar survey. This could be done by developing a more complete energy questionnaire where all relevant information is collected in that single survey.
The purpose with the statistics is to provide information on average stationary energy consumption per household for different household and dwelling types, and information about heating equipment in dwellings. Energy consumption in private cars is not included. The results could be used to calculate total figures for all households in a country by combining average energy consumption per household with the number of all households in a country, but this has not been the main purpose in Statistics Norway. Total energy use for all households in Norway is calculated by using other sources and methods.
The survey of consumer expenditure is based on computer assisted personal interviews and detailed accounting of private expenditures during a two week period, from a representative sample of private households. The questions on energy are included in the personal interview. Information from registers on household income and education level is combined with the household data at a later time.
It is voluntary to respond to the questionnaire, and the response rate is about 50 per cent. The non-respondents are not equally distributed among all the household groups and in order to correct for sample bias, corrections have to be made for the non-response as described in this paper.
It should be mentioned that Norwegian household energy consumption is based on electricity in a much larger degree than in most other countries. In order to get good data for the electricity consumption, we collect these data from the household's electricity supplier. For countries where, for instance, natural gas is the main energy source, it could be better to put more effort into getting better data for gas. This could be done by asking several questions about gas or by collecting information from the households' gas supplier in a similar way as we do for electricity especially since gas use is often measured for each household with a gas meter in countries where gas is important.
The website of the survey is the following: http://www.ssb.no/english/subjects/01/03/10/husenergi_en/
Contact person: Ann Christin Bøeng. E-mail:
Outline of the paper
The different activities and their sequence for developing household energy statistics is illustrated in a rough process diagram on page 4. Then follows administrative information about the statistics, background and purpose, more details about the methodology and also a discussion about uncertainty and possible sources of errors. Questionnaires and examples on tables are attached in the appendixes.
Contents
Statistics for residential energy consumption per household 1
A graphic illustration of the sequence of action to produce household energy consumption statistics 4
1. Administrative information 5
1.1. Name 5
1.2. Subject group 5
1.3 Responsible Authority and division 5
1.4 Reference period 5
1.5 Frequency 5
1.6 Timeliness 5
1.7 Punctuality 5
1.8 Regional level 5
1.9. Legal authority 5
1.10. Legal document 5
1.11 International reporting 5
2. Background and purpose 5
2.1. Purpose and history 5
2.2. Users and applications 6
3. Concepts, variables and classifications 6
3.1. Definitions of the main concepts and variables 6
3.2. Standard classifications 6
4. Statistics production 7
4.1. Population 7
4.2 Data sources 7
4.3. Sampling 7
4.4. Collection of data 7
4.5. Control and revision 8
4.6. Estimation 8
4.7 Resource requirements 9
5. Sources of error and uncertainty 9
5.1. Measurement and processing errors 9
5.2. Non-response errors 10
5.3 Sampling errors 10
5.4. Other sources of error 10
6. Comparability and coherence 10
6.1. Comparability over time and space 10
6.2. Coherence with other statistics 11
7. Availability 11
7.1. Publications and other links 11
7.2. Microdata 11
7.3. Other documentation 11
7.4 Confidentiality 11
Appendix 1 Additional energy questions to the survey of consumer expenditure 12
Appendix 2 Some important questions from the survey of consumer expenditure 14
Appendix 3 Questionnaires to the electricity plants 16
Appendix 4 Example on tables: 18
A graphic illustration of the sequence of action to produce household energy consumption statistics
1. Administrative information
1.1. Name
Energy consumption per household
1.2. Subject group
01.03.10 Energy (on Statistics Norway's website: http://www.ssb.no/english/subjects/)
1.3 Responsible Authority and division
Statistics Norway, Division for Energy and Industrial Production Statistics.
1.4 Reference period
Calendar year
1.5 Frequency
The survey has been carried out for the years 1993, 1994, 1995, 2001 and 2004. A survey for 2006 is in progress. The first survey was originally conducted because of a request from the Ministry of Industry and Energy (currently: Ministry of Petroleum and Energy). The frequency of the survey has been depending on external interest and financing. However, the intention is to continue to conduct these surveys regularly every second or third year, because it is of great value to follow the development in households' use of energy, and see how this varies for instance with fluctuating energy prices.
1.6 Timeliness
Results can be published about 10 months after the reference period, but due to lack of resources, the results have been published about two, or two and a half year after the reference period.
1.7 Punctuality
The statistic has always been published at the advance release date.
1.8 Regional level
The results are mainly published on national level, but some tables also show the energy consumption per household by region (regions specified in point 3.2).
1.9. Legal authority
The survey is voluntary for households. Statistics Norway has a legal act to collect data, but seldom uses this in surveys of private persons. The data for electricity consumption are collected from the households' electricity supplier pursuant to §2-2 and 2-3 of the Statistics Act.
1.10. Legal document
No legal document
1.11 International reporting
Not reported internationally
2. Background and purpose
2.1. Purpose and history
The purpose of the statistics is to present figures for average energy consumption per household for different household types and house types, and to study the development over time. This shows how the energy consumption varies between different types of households and indicates what kind of factors influence the households' energy consumption. The statistics also comprise combinations of heating equipment in dwellings, which give an indication of the energy flexibility in households or the households' possibility to switch between different energy sources. Using the survey of consumer expenditure as a basis, we have access to a large amount of relevant background information. This makes it possible to study correlations between energy consumption and relevant factors such as house types, dwelling area, number of persons in household, income etc. The survey can also be used to study the effect on energy consumption of heat pumps by comparing similar households with and without heat pumps. In addition, questions about other energy efficiency efforts (since 2001) enable the study of the extent and effects of such efforts in the households.
The survey was first carried out for 1993 and then repeated for 1994, 1995 and 2001. A similar study of energy consumption in households was conducted by Statistics Norway for 1990, but other sources and methods were used in that survey. The results for 1990 are therefore not directly comparable with the results for the other years. For 1990 and 2001, the data were also used in analyses of the average share of electricity consumption for different purposes such as cooking, space heating, water heating etc. For 2001, this was estimated on basis of additional questions in the energy questionnaire that could be used for these kind of analyses, as for instance questions about the fridge, use of hot water, frequency for use of dish washer, oven etc.
2.2. Users and applications
The statistics are among other things used as background information in energy reviews/reports in ministries, in various types of research and in Enova (a public enterprise which works towards more efficient and environmentally friendly energy consumption). The data and results are used for research purposes on the Research Department in Statistics Norway, Unit for Energy and Environmental Economics. There is also much public interest in the results.
3. Concepts, variables and classifications
3.1. Definitions of the main concepts and variables
Income: Income. The information is taken from tax assessment registers. Income is calculated as pensionable earnings - assessed taxes + tax deductions.
Household. A household consists of all persons living in the same dwelling and eating at least one meal together every day. Persons who are temporarily absent due to school; vacation, admission to hospital, military service etc. are included.
3.2. Standard classifications
Region: The various regions consist of the following counties:
Oslo
Akershus
Hedmark and Oppland
South-east Norway (Østfold, Buskerud, Vestfold and Telemark)
Agder and Rogaland (Aust-Agder, Vest-Agder and Rogaland)
Western Norway (Hordaland, Sogn og Fjordane, Møre og Romsdal)
Trøndelag (Sør-Trøndelag and Nord-Trøndelag)
Northern Norway (Nordland, Troms and Finnmark)
See also reference to the following standard classification for Norwegian regions:
http://www3.ssb.no/stabas/ItemsFrames.asp?ID=1304517&Language=en&VersionLevel=classversion&MenuChoice=Language
House type: The classification of house types is the following:
Farming houses
Detached houses
Row houses/semi-detached houses (row houses, chain housing, two, three, four family houses etc.)
Blocks of flats etc. (large houses with many dwellings and combined dwelling and office / industrial buildings)
The classification is aggregates based on the following standard for building types:
http://www3.ssb.no/stabas/ItemsFrames.asp?ID=4222302&Language=en&VersionLevel=classversion&MenuChoice=Language
Categories of energy sources in the tables
Electricity
Fuel wood, coal, coke: Fuel wood, coal and coke are published together, but the main part is fuel wood as very few households use coal or coke.
Heating kerosene and heating oil: Figures for oil and kerosene are collected separately, but published together as only a small share of households use oil or kerosene.
District heating: Data for district heating are collected from the households. However, because very few households use district heating and often lack information on how much they have used, this is not published as a separate figure in the tables, but appears as the difference between total energy consumption and the other energy sources in the tables.
4. Statistics production
4.1. Population
The statistics are based on a sample survey where the household is the statistical unit.
4.2 Data sources
The source is the annual survey of consumer expenditure and related information from registers on income. For the years 1993, 1994, 1995, 2001 and 2004, the survey of consumer expenditure has been supplemented with additional questions on energy consumption and heating equipment in order to give a better basis for statistics and analyses of the energy consumption in households. Data for electricity consumption are collected from the households' electricity supplier.
4.3. Sampling
The survey of consumer expenditure is based on computer assisted personal interviews and detailed accounting in a representative sample of private households based on a sample drawn from persons ages 0 to 79. The households to which these persons belong become a part of the sample. A disadvantage with this method is that one-person households become underrepresented, because it is more likely to draw a person from a big household. We correct for this bias by weighting the data (see chapter 5.2)
The questions on energy are asked in the final personal interview. Information from registers on income and education are attached later. The annual sample is 2200 persons. Persons living in institutions such as hospitals, prisons and nursing homes are excluded from the sample.
The survey of consumer expenditure is based on personal interviews and detailed accounting in a representative sample of 2 200 households. For 2004, 48 per cent of the households did not respond, and the net sample became 1 148 households. The tables for combination of heating equipments in dwellings are based on information from all 1 148 households, while the tables for energy consumption are based on information from a somewhat smaller sample of 1 091 households. This is due to the fact that if important data for energy consumption or background information about dwelling area, year of construction etc. are missing, the households are excluded from the sample used in energy calculations