Scottish Vacant And Derelict Land Survey 2021

Annex A – Data Quality and Processing

A.1. Data Quality

Details of the quality assurance checks undertaken on survey returns have been published on our website. View details of the Scottish Vacant and Derelict Land Survey quality assurance checks

Local authorities may not update all historic site information every survey, consequently some site information may not be current. For example, a site may be sold and change ownership type. A change like this could happen without a local authority’s knowledge.

A.2 Planning Authority response rate

The overall data quality for a particular year will depend on how many planning authorities have updated their survey for that year. If a planning authority does not update their data then data for the previous year is rolled forward. This will provide a reasonable estimate but will not take account of any changes in the latest year. Data quality will also be affected by the number of years since the last update. Dundee City and West Lothian have not updated their surveys since 2019 so their data is carried over from their latest update in 2019.

Annex Table 5 records local authority annual participation in the survey each year since 2015.

In 2020, eight authorities did not submit a return which would have had a large impact on the survey results and the decision was taken not to publish survey results that year. This reflected the impact of the Covid-19 pandemic on the capacity of the planning authorities to carry out a survey. The pandemic has continued to have an effect on how some authorities have conducted their survey in 2021 and it’s likely that the some new sites will not have been identified since 2019. Some authorities provided specific information on the impact of the pandemic on their survey returns and this is available in the General Points of the tables spreadsheets. These impacts should be taken into account when using and interpreting the data for the years 2020 and 2021.

These response rates should be borne in mind when using and interpreting the figures for these authorities, including any time series and Scotland totals.

A.3 Removal and Addition of Sites

The means by which new sites are detected are largely centred on the expert knowledge of local authority planning officers supported by the SVDLS guidelines which clearly state the definitions for the recording of derelict and urban vacant land. The survey relies on the consistent application of definitions between local authorities and within a local authority through subsequent years. The guidelines are regularly reviewed and modified to assist in the provision of uniform returns. Some of the changes reported in Annex C - sites removed for definitional reasons is the result of a reappraisal of the survey guidelines by local authorities prior to the 2021 survey. Download the Scottish Vacant and Derelict Land Survey guidance for authorities (PDF).

A.4 Changes to Site Details

Changes in site details can cause difficulties in interpreting the data. The most notable are when two separate sites become joined by the inclusion of a further piece of vacant or derelict land, and alternatively when a single site has a central area brought back into use, such that the remaining disused area does not form a single contiguous site. The first of these scenarios may cause difficulties if data regarding previous use etc. for the sites differ. Where this happens, details from the largest contributing site are used to describe the new, compound site. The introduction of GIS systems has allowed planning officers to improve data quality, leading to some changes in site sizes recorded.

A.5 Changes in Historic Data, 2015-2021

As part of the 2021 survey, work was undertaken to improve the quality of the data supplied in the previous 2015 to 2021 returns. This was done to allow for improved time series analysis. This included removing sites identified by the local authority as being previously incorrectly included in the survey, adding in sites that the local authorities indicated should have been included in previous surveys and correcting historic sizes as a result of more accurate boundary mapping. A number of site sizes were changed during this years’ survey as a result of more accurate mapping of the sites by local authorities through increased use of GIS tools. The revised data for 2015 to 2021 is used throughout the tables and time series analysis of this bulletin.

The SVDLS has been running continuously since 1993. Historical data on the amount of derelict and urban vacant land in Scotland for the years 2000 to 2014 is shown in Annex Table 1. Data for earlier years is available in previous publications. 1996 to 2004 data has remained unaltered since the 2004 survey publication. 2005 data was last revised in 2011 and each subsequent publication revised historical data for the six years preceding the publication with the 2021 publication updating historical data from 2015-2021. Thus care should be taken when comparing 2000-2014 data in Annex Table 1 to the data shown in this publication.

General notes - at sections 3 and 4 apply.

Specific note 15 - care should be taken when comparing this data to that published for the years 2012-2018 in the main part of this bulletin. The data above has not been amended to take account of all land removed for definitional reasons or other previous reporting errors.

A.6 Land area eligible

Local authorities are asked to note all derelict land for the survey but to limit recording vacant land to land within settlements as defined in their latest council approved local plan. Consequently, the actual land area surveyed for vacant land is often considerably smaller than the total land area of each local authority, especially in more rural areas.

A.7 Coverage of Settlements

Local authorities were asked to survey for vacant land within all settlements defined in their latest council approved local plans. However, due to resource constraints some local authorities (particularly those covering large rural areas), were unable to do a full survey of every settlement for vacant land. All returned surveys covered every settlement with a population of 2,000 or more. To ensure consistency, the statistics presented on vacant land throughout this bulletin refer only to land located within settlements that have a population of at least 2,000 (according to the local plan). Some local authorities also undertook either a full or partial survey for vacant land in settlements of under 2,000 in population - these are reported separately from the rest of the bulletin in Annex Table 2.

General notes - at sections 3 and 4 apply.

Specific note 20 - Glasgow conducted a partial survey in 2021 and some sites were recorded as re-used but no new sites were added due to difficulty with resource for the survey. Dundee City and West Lothian have not updated their survey since 2019 so no new data is available on new site in 2021. Details of survey return rates back to 2015 are shown at Annex D.

Specific note 24 - six authorities reported various impacts of the COVID-19 Pandemic on their survey return in 2021. More details are provided at sections 3 and 4. These impacts should be borne in mind when using and interpreting the figures for these authorities in the year 2021, when comparing the 2021 figure to other years and when interpreting the Scotland total for 2021.

A.8 Estimate of the proportion of local authority population living within a defined distance of a Derelict Site

Tables 9 and 10 in the publication show estimates by local authority of the percentage of their population living within various distances of derelict land. For Table 9 a circular buffer zone based on the area of each derelict site was drawn around the grid co-ordinate points supplied for that site. This gives an estimated boundary for each site therefore data should be treated with care as actual site boundaries are not being used. Table 10 used the same estimated site boundaries and also estimated the proportion of local authority population living in close proximity to land that has been derelict prior 2001. In addition to derelict sites which were identified as being derelict prior to 2001 the analysis also included sites where the length of time derelict is unknown but where the first site inspection occurred prior 2001.

To measure the proportion of each local authority population that lives within a certain distance of derelict land, a national data set was constructed that estimated the population of each property identified as likely to be residential in the latest National Records of Scotland (NRS) Address Register. Average household size figures were calculated by dividing NRS census (2011) population by census household counts at the Census Output Area (COA) level. All records in the Address Register that were identified as likely to be residential were assigned an estimated household size figure based on the average household size of the COA they fall within.

To ensure consistency with previously published population estimates, the latest available small-area estimates of population by NRS were used as a control factor on the calculated household size figures. For each property in the Address Register based dataset, the distance to the nearest estimated derelict site boundary was calculated, to highlight those properties within the defined distance of derelict land. Those properties’ estimated populations were then aggregated up by data zone to give a proportion of each data zone’s population (and hence each local authority’s population) estimated to live within the defined distance of derelict land.

Overall it is estimated that 27.2% of the population of Scotland live within 500 metres of a derelict site in 2021. The data published in Tables 9 and 10 on proximity will also be available at data zone level on the statistics.gov.scot website. Visit the statistics.gov.scot site for open access to Scotland's official statistics . The website will be updated with data zone level data for 2021 following the release of this publication.

A.9 Deprivation Areas using Scottish Index of Multiple Deprivation (SIMD 2020)

Table 11 shows the amount of derelict and urban vacant land located within Scotland’s 15% most deprived data zones. Those data zones are identified using the 2020 Scottish Index of Multiple Deprivation (SIMD). The SIMD 2020 identifies small area concentrations of multiple deprivation across all of Scotland. It contains 33 indicators in seven domains: Current Income, Employment, Health, Education, Skills and Training, Geographic Access to Services, Housing and Crime. Sites in the SVDLS are identified as being located within Scotland’s most deprived areas if their grid co-ordinate point (i.e. the centre of the site) falls within a 15% most deprived data zone. Care should be taken with this data as there are instances of sites crossing data zone boundaries, hence part of the site may be in a 15% most deprived data zone, whilst the other part could be outwith. Further information on the SIMD 2020 project can be found on the Scottish Government’s web page at: Visit the Scottish Index of Multiple Deprivation webpage.

A.10 Land surveyed by Loch Lomond and the Trossachs National Park Authority

From 2011 Loch Lomond and The Trossachs National Park took responsibility for surveying vacant and derelict land within the park boundaries. These sites are no longer recorded in Argyll and Bute, Perth and Kinross, Stirling and West Dunbartonshire local authority boundaries, and are separately identifiable as Loch Lomond and The Trossachs National Park from 2011. Prior to 2011 these sites were classified within the relevant local authority boundary.