Scottish House Condition Survey: Key Findings 2011

1 Introduction

1. The Scottish House Condition Survey (SHCS) is the only national survey of housing and households undertaken in Scotland. It combines both an interview with occupants and a physical inspection of dwellings to build up a picture of Scotland's occupied housing stock which covers all types of households and dwellings across the entire country - whether owned or rented, flats or houses.

2. The format of the SHCS allows the physical data recorded by professional, trained surveyors to be combined with the social data from the interview with the householder. This 'social' interview covers a range of topics such as household characteristics, tenure, neighbourhood satisfaction, dwelling satisfaction, health status, income. The result is a powerful data set for examining the condition and standard of dwellings and the views and experience of the people living in those dwellings.

3. This is the eighth 'Key Findings' report since the SHCS changed to a continuous format in 2003. Before 2003, surveys were conducted in 1991, 1996 and 2002 and typically consisted of about 15,000 paired social interviews and physical surveys.

4. The continuous format was introduced to allow more flexibility of content and to assist in the monitoring of Ministerial targets. The 2003/4^[1], 2004/5, 2005/6, 2007, 2008, 2009, 2010 and, now, the 2011 surveys each gathered data from almost 4,000 households and dwellings with paired social and physical data available for around 3,000 of these. A similar sample size to the previous surveys (15,000 cases) is achieved over each five year period since the continuous format was introduced.

5. In 2009, the SHCS was designated as a National Statistics product by the UK Statistics Authority (UKSA). This demonstrates that the SHCS statistics are accurate, trustworthy and compliant with the high standards required of National Statistics.

6. The results in this report are based on fieldwork from January to December 2011. Given the sample size of around 3,000 paired households, it is not possible to provide in-depth estimates for a number of topics. Therefore this report sets out key, high-level, national estimates relevant to a number of important policy areas.

7. Subsequent chapters cover the following key findings from the Scottish House Conditions Survey:

• Key Attributes of the Scottish Housing Stock: this covers key indicators such as dwelling type and age, and whether a dwelling is on or off the gas grid.
• Energy Efficiency: this chapter presents an analysis of the energy efficiency of the housing stock including presence and level of insulation. Further analysis is based on three energy efficiency measures: the National Home Energy Rating (NHER); the UK Government's Standard Assessment Procedure for the Energy Rating of Dwellings (SAP, 2005); and approximated Energy Efficiency Ratings (EERs) as found in Energy Performance Certificates (EPC). Also included in this chapter are modelled mean and total CO₂ emissions.
• Fuel Poverty: this chapter presents an analysis of the number and characteristics of households in fuel poverty and extreme fuel poverty.
• Housing Quality: this part of the report provides estimates of the number of dwellings passing and failing the tolerable standard and the Scottish Housing Quality Standard (SHQS). It also covers dampness, condensation and disrepair.
• Notes and Definitions: the final chapter provides information about the content of the survey and the key concepts used in this report. Discussion on the reliability of the estimates is also included.

8. Care needs to be taken when comparing estimates in this report with those from the 1991, 1996 and 2002 reports. Some features of the survey have not altered consisting, as it does, of a social interview followed by a physical inspection. However, the use of continuous, year-round fieldwork was a basic change in the methodology introduced in 2003/4 and cannot be discounted as a possible explanation of change.

9. For 2007 to 2011, the SHCS changed contractors from the Office for National Statistics to Ipsos-MORI. We can not discount the possibility that this may have caused some year-on-year changes.

10. Care must also be taken in comparing dwelling numbers (rather than proportions) between each survey year as the base number of occupied dwellings changes. Population totals on the number of dwellings in the SHCS are obtained by weighting the survey results to estimates of the number of households in Scotland published by National Records of Scotland (previously GROS)^[2] for 2002, 2003/4, 2007, 2008, 2009, 2010 and 2011 or the number of occupied dwellings derived from CTAXBASE^[3] data on chargeable dwellings supplied by each of Scotland's LAs (for 2004/5 and 2005/6). The number of occupied dwellings used in the SHCS for each survey year are shown in Table 1.

Table 1 Base number of dwellings by survey year, 2003/4-2011, (000s)

Source: Continuous SHCS

11. The growth of the Scottish housing stock can give the impression that more dwellings now fall into certain categories (more owner occupiers for example) so it may be important to compare rises in proportions as well as numbers.

12. The SHCS is a sample survey. All survey figures are therefore estimates of the true prevalence within the population and will contain some error associated with sampling variability. However the likely size of such variability can be identified, by taking account of the size and design of the sample. Sections 6.1 - 6.3 provide further discussion of confidence intervals and sampling errors associated with estimates of proportions for characteristics directly observed in the survey.

13. In addition to sampling variation, 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. Such errors have not been quantified.

14. Different types of estimates are subject to differing levels of uncertainty associated with sampling and design. For example estimates of change (i.e. figures relating to comparisons across survey years) are generally subject to greater sampling error than point-in-time estimates (i.e. figures relating to one survey year only) and such errors would be understated by figures in Table 41 in Section 6. There is more uncertainty associated with complex measures, such as the fuel poverty rate and this is not fully captured by figures in Table 41.