Final report: Reducing burglary through Secured by Design: a meta-analysis

Abstract

Secured by Design (SBD) is a UK-based crime prevention initiative that sets security standards for the built environment. Buildings that meet prescribed security standards are awarded SBD status and, all things being equal, are assumed to be at lower risk of crime. SBD draws heavily on the principles of situational crime prevention and crime prevention through environmental design.

This study reviewed the evidence on whether properties that meet SBD standards experience less crime than properties that do not. Following a comprehensive search of the literature, nine UK studies were included in our review. Eligibility was limited to studies that (1) measured levels of crime in SBD developments compared to matched non-SBD developments or (2) reported changes in crime before and after SBD accreditation in a treatment and control group. This sample included studies of new dwellings built to SBD standards (n = 7) and existing dwellings refurbished to SBD standards (n = 2).

Our analysis found that eight of the nine included studies reported that SBD accreditation was associated with lower levels of burglary. In only three of these studies was the observed effect statistically significant, however. Synthesising data across all nine studies, our results indicate that overall, burglary in SBD properties was 53% lower than in non-SBD properties. The impact on burglary was greater still when focussing only on new properties built to SBD standards. For this sample of studies, we found a 65% relative reduction in burglary compared to matched non-SBD properties. No statistically significant effect was observed for other forms of crime and disorder. Insufficient data meant that we could not measure the impact of SBD specifically in refurbished properties nor could we test for crime displacement or diffusion of crime control benefits. Importantly, there was no evidence of SBD leading to an increase in crime and disorder.

The findings from this review support the general hypothesis that more secure households experience less burglary. They also lend further support for the basic idea that crime can be reduced by removing opportunities to commit it. From a policy perspective, our results re-emphasise the importance of engaging with manufacturers and design professionals to ensure that crime prevention is considered at the design and planning stage of urban developments. More specifically, our findings indicate that upgrading and/or maintaining effective SBD standards is a sensible strategy to reduce burglary. Simply put, properties which met SBD standards were significantly less likely to be burgled. Although the results of this study are generally positive, there are some notes of caution. Only a small number of studies met the inclusion criteria for this review (n = 9). This was most pronounced for studies of existing properties refurbished to SBD standards (n = 2). Of those studies that were included in the review, weaknesses were identified concerning study design and limited data were provided on factors such as the quality of SBD measures and crime displacement. Moreover, three of nine included studies are now over twenty years old and relate to SBD standards that have been superseded. Relatedly, the quality of security in non-SBD properties has, in general, improved over time, influenced by a combination of technological developments, policy changes and, potentially, the growth and influence of SBD itself. One consequence of these general improvements is that the difference in security between SBD and non-SBD developments may, on average, be less pronounced today than it was thirty years ago. This raises concerns about the equivalence of SBD vs non-SBD evaluation sites; some properties might meet SBD standards despite not being SBD accredited, thereby muddying SBD vs non-SBD comparisons. Newer high quality evaluation studies are therefore needed to determine whether the positive effects reported here hold in contemporary urban environments, with greater attention paid to the quality of household security being compared across SBD and non-SBD developments. Furthermore, to advance the evidence base for SBD, we recommend that future evaluation studies include a wider range of outcome measures (including displacement) and put data collection measures in place better to understand what specific aspects of SBD affect crime, through what mechanisms and under what conditions.