Where an estimate is representative of two or fewer sampled cases, or the base sample is fewer than 30 cases, the statistic is suppressed. Where a table shows missing values, the data has either been suppressed on disclosure control grounds, or because there were no sampled cases.

The United Kingdom Statistics Authority has designated these statistics as National Statistics, in accordance with the Statistics and Registration Service Act 2007 and signifying compliance with the Code of Practice for Official Statistics. The designation of the Scottish House Condition Survey as National Statistics was initially confirmed on 30 March 2010 following an assessment by the UK Statistics Authority and re-confirmed on the 16 October 2020 following a compliance check by the Office for Statistics Regulation.

From 2012 onwards, the SHCS is a module of the Scottish Household Survey (SHS). In general, around one third of respondents to the SHS are invited to participate in a follow-up inspection by SHCS building surveyors.

The SHCS is a sample survey. All survey figures are estimates of the true prevalence within the population and will contain some error associated with sampling variability. The likely size of such variability can be identified, by taking account of the size and design of the sample. Users may estimate the margin of error by using the statistical significance tool included with the local authority tables published on the SHCS website.

In addition to sampling variability, there are other sources of uncertainty, such as those arising from incomplete responses or failure to secure participation in the survey from each sampled household. Where non-response is not random, i.e. some types of household are less likely to participate than others, bias is introduced into the survey data. Such errors have not been quantified in the main Key Findings reports, or for these aggregated years of data.

In general, the smaller the sample size, the greater the uncertainty around the estimate, so more care must be taken when using smaller subsets of the survey sample for analysis. In order to reach a sufficient sample size for local authorities, it is necessary that three years’ worth of data are combined.

95% confidence ranges help inform whether a difference between two estimates is statistically significant or not. Where the upper and lower ranges of the two estimates being compared do not overlap, there is a statistically significant difference at the 95% level between them. Instances where there is a small overlap can also result in a statistically significant difference – you may refer to the following Methodology Glossary for information on carrying out this more detailed analysis. However, as these figures are rounded to the nearest 0.1 percentage point, there is a chance this detailed analysis would not produce accurate results in marginal cases. Finally, where a lower or upper confidence interval would lie outside the 0-100% range, it has been set at either 0% or 100%, as appropriate. Further information on SHCS estimation can be found in Section 7.1 of the 2019 Key Findings report.

Each three year average of data is a snapshot in time, and because of overlapping years. consecutive releases should not be used to quantify changes in time. Where appropriate, considering the points over tenure and energy modelling differences detailed in Coherence and Comparability, three year periods with non-overlapping years may be compared. Furthermore, single year estimates can be compared to other single year estimates, where appropriate. However, single year estimates should not be compared to three year averages. For example, should a Local Authority estimate be compared to a national estimate, the corresponding three-year average national estimate should be used.

For a complete description of the survey's structure and its reliability, please refer to the SHCS Methodology Notes published on the SHCS website.

Users should be aware that the underlying energy model for estimating fuel poverty changed in 2010 and 2014, and the method of sourcing price information changed from 2013. For fuel costs, 2011 and 2012 include the Warm Homes Discount (WHD), while for 2013 onwards, fuel costs include both the WHD and the price source adjustments mentioned above. From 2016, a further improvement is included by assigning pre-payment metered fuel prices to the relevant households.

Because of a routing error tenure information is not available for a small number of “rent free” cases in the 2012 and 2013 surveys (46 in 2012, 42 in 2013). This was rectified for the 2014 fieldwork and the full sample has been used when reporting on tenure for subsequent years.

Consequently, these cases are excluded from tenure breakdowns for data encompassing up to and including 2013, and also applies to data covering the 2010-2012, 2011-2013, 2012-2014 and 2013-2015 periods. Tenure breakdowns are reported for single years on a consistent basis from 2014 to include these “rent free” categories.

In 2015, a uniform retirement age of 65 and above was introduced when building "Older" Household Types. All years in these data from 2010 onwards been harmonised to match this Household Type definition, and will not necessarily match the definition used in earlier Key Findings reports. Therefore, please refer to the 2019 SHCS Key Findings Report for a complete definition of the Household Types used in this data release.

A summary document highlighting key findings of the 2017-2019 Local Authority release can also be found on the SHCS website.

The annual SHCS Key Findings report presents the latest national data for key measures of energy efficiency, fuel poverty, energy perceptions and housing quality. The local authority breakdowns provide key indicators at local authority level relating to different household and dwelling types.

In July 2019 the Fuel Poverty (Targets, Definition and Strategy) (Scotland) Act received Royal Assent. This Act contains a new definition of fuel poverty which affects how fuel poverty is to be defined and measured.

The Fuel Poverty (Targets, Definition and Strategy)(Scotland) Act 2019 also set targets to eradicate fuel poverty. The 2040 targets are that:

• no more than 5% of households in Scotland are in fuel poverty
• no more than 1% of households in Scotland are in extreme fuel poverty
• the median fuel poverty gap of households in Scotland in fuel poverty is no more than £250 adjusted to take account of changes in the value of money.

The release of SHCS Local Authority data lags the publication of the annual SHCS Key Findings Report to allow for an aggregation of three years’ worth of data. The data are published in the first instance on the SHCS website, and the Open Data Platform will be updated as soon as possible after this. A summary document highlighting key findings of the 2017-2019 Local Authority release can also be found on the SHCS website.

Routine revisions and updates are applied to previous years as methodologies are improved or indicator definitions are changed. A full list of revision and updates can be accessed on the SHCS Revisions and Corrections website.