Secure doors and windows with proper locks, install an exterior motion-sensor light, and reliably lock up when leaving: physical locks and lighting prevent residential burglary far more effectively than standalone alarms

Empirical crime data from the UK indicates that households combining quality door locks with window locks face only one-twelfth the risk of residential burglary compared to unprotected homes. Adding an external motion-activated security light reduces burglary risk to less than one-thirtieth. Installing a standalone burglar alarm without basic physical locks shows no demonstrable crime-prevention benefit. This guidance targets unforced and forced property theft, not armed home invasion while occupants are present.

Upgrading deadbolts, adding window security latches, and installing an exterior motion-activated sensor light generally costs a few dozen to a few hundred RMB ($15–$70 USD); replacing an entire certified security entrance door costs 1,000+ RMB. The behavioral challenge is consistently double-locking doors and windows whenever leaving home, including warm seasons when windows are cracked for ventilation.

Analysis of the Crime Survey for England and Wales (37,416 households surveyed between 2008 and 2012) compared residential security measures between victimized and non-victimized households. While completely unsecured homes represented only 4.9% of the overall population, they accounted for 36.6% of all completed domestic burglaries. Researchers calculated the Security Protection Factor (SPF), representing the reduction in burglary odds relative to unsecured premises: 1) Homes equipped with both door deadbolts and window locks achieved an SPF of 12.54, slashing burglary risk by roughly 12-fold. 2) Combining door locks, window locks, and external sensor lighting achieved an SPF of 34.41 (over a 30-fold risk reduction). 3) Adding interior timer lights pushed the SPF to 49.1. Installing five or more security gadgets offered no additional statistical protection beyond the optimal three-device combination. Notably, standalone burglar alarms without physical door/window locks were associated with higher burglary odds than no security (partly reflecting post-victimization installation), and fake dummy alarm boxes actually correlated with elevated burglary attempts. Crucially, locks must be actively engaged: between 1993 and 2006/2007, forced-entry burglaries (picking locks, smashing windows, forcing doors) fell by 77% (from 31 to 7 per 1,000 households) as physical security standards rose, whereas unforced walk-in burglaries through unlocked doors or windows remained flat at 7 per 1,000 households.

Controversy: Earlier longitudinal studies (1992–1996 data) found modest protective effects for alarm systems; authors note that modern alarms without physical barriers do not physically deter rapid grab-and-run intruders. Data originate from UK observational surveys, which lack randomized assignment, justifying grade B. These measures deter property theft; they do not evaluate defense against confrontational home invasion. If you encounter an intruder inside your home while present, prioritize safe retreat and call emergency police immediately (see Chapter 8, Rule 10); lawful defense boundaries against imminent violent attack are covered in Chapter 8, Rule 11. Tenants altering locks or adding window fixtures must obtain written landlord permission beforehand under Civil Code Article 715 to avoid liability for property restoration. When purchasing security doors, look for compliance with mandatory national standard GB 17565-2022. Benefit magnitude is categorized as Moderate based on loss prevention and personal safety assurance. Primary beneficiaries are yourself and your household.

Tseloni A, Thompson R, Grove L, Tilley N, Farrell G (2017). The effectiveness of burglary security devices. Security Journal 30(2):646–664. https://doi.org/10.1057/sj.2014.30；Tilley N, Thompson R, Farrell G, Grove L, Tseloni A (2015). Do burglar alarms increase burglary risk? A counter-intuitive finding and possible explanations. Crime Prevention and Community Safety 17(1):1–19. https://doi.org/10.1057/cpcs.2014.17；Tseloni A, Farrell G, Thompson R, Evans E, Tilley N (2017). Domestic burglary drop and the security hypothesis. Crime Science 6:3. https://doi.org/10.1186/s40163-017-0064-2；国家市场监督管理总局、国家标准化管理委员会 (2022). GB 17565-2022 防盗安全门通用技术条件. https://openstd.samr.gov.cn/bzgk/gb/newGbInfo?hcno=A75C1C66CB989D0A40BFA7A262C93290；全国人大 (2020). 民法典（第七百一十五条）. https://www.spp.gov.cn/spp/fl/202006/t20200602_463888.shtml