A patented window lock that allows ventilation — developed in South Africa — is being adopted by homeowners across five continents as concerns about air quality, mould and home security continue to rise.
The device, called LockLatch®, solves a problem that has frustrated homeowners for decades: how to keep a window open for fresh air without creating a security vulnerability. Traditional window locks only function when the window is fully closed, forcing residents to choose between breathable air and a locked home.
The ventilation-security dilemma
Research published in the International Journal of Environmental Research and Public Health has consistently linked poor indoor ventilation to increased rates of respiratory illness, mould-related allergies and elevated CO2 levels during sleep. For households in warmer climates — including much of South Africa, Australia and parts of the UK — natural ventilation through open windows is not a luxury but a daily necessity.
Yet police crime statistics across these same regions show that open or unlocked windows remain one of the most common entry points for opportunistic burglars. In the UK alone, an estimated 23% of domestic burglaries involve entry through a window.
The result is a widespread compromise: homeowners close and lock windows for security, sacrificing air quality and comfort. Others leave windows open and accept the risk. Neither option is adequate, and for families with young children, the stakes include the danger of child safety incidents involving open windows in multi-storey homes.
How the device works
The LockLatch® is a stainless steel arm that mounts to the window or door frame. It is adjustable between 9cm and 17cm, allowing the user to set a fixed opening width. A lockable security pin then holds the arm in position. Once locked, the window cannot be opened further or forced closed without the key.
The effect is a window that sits open at a controlled width — wide enough for ventilation but physically locked against intrusion. The device fits any window or door material, including aluminium, uPVC, timber and steel, and works regardless of whether the window opens inward, outward or slides.
Three products for different needs
The LockLatch® range now includes three variants:
- LockLatch® — adjustable 9 to 17cm, the standard model for home security and ventilation.
- PetLatch® — adjustable 14.5 to 23cm, designed as a dog door alternative for households that want to give pets outdoor access through a window or door.
- MiniLatch® — adjustable 4.5 to 8cm, developed for situations requiring narrow openings, such as keeping cats indoors or excluding wildlife.
All three are manufactured from C304 stainless steel — the same grade used in marine and medical applications — and carry a lifetime guarantee.
Night-time ventilation and sleep quality
One of the strongest use cases for a window lock that allows ventilation is overnight airflow. A 2017 study by Eindhoven University of Technology found that participants who slept with open windows reported better sleep quality, lower CO2 concentrations in their bedrooms and fewer next-day complaints of drowsiness.
For many households, however, leaving a bedroom window open at night is considered too great a security risk. A ventilation window lock that remains physically secured addresses this directly. The device can be fitted to bedroom windows so that occupants sleep with fresh air flowing through a locked opening.
Medical professionals have also noted the role of ventilation in reducing the spread of airborne viruses. During the COVID-19 pandemic, public health agencies worldwide recommended increased indoor ventilation as a key mitigation measure. For homes without mechanical ventilation systems, an open window remains the simplest solution — provided it can be secured.
Mould, moisture and the cost of closed windows
The financial case for a window lock that allows ventilation extends beyond energy savings. In the UK, the National Health Service estimates that damp and mould-related housing conditions contribute to respiratory problems affecting millions of households annually. In South Africa, coastal and subtropical regions face similar challenges, with trapped moisture leading to structural damage and health complaints.
Homes that remain sealed for security purposes are particularly vulnerable. Without natural airflow, condensation builds on walls, ceilings and window frames. Over time, this creates the conditions for black mould — which is both expensive to remediate and hazardous to health. A secured ventilation solution breaks this cycle by allowing continuous airflow without the security compromise.
Installation and availability
The product installs in under 15 minutes with a drill and screwdriver or rivet gun. No locksmith or specialist contractor is required. Each unit ships with all fixings and clear instructions. The features include an adjustable arm, lockable pin and universal fit design that works on any window or door frame.
LockLatch® is available worldwide and ships from distribution centres in South Africa, the United Kingdom, the United States, Australia and New Zealand. The product has been adopted by homeowners, landlords, property managers and hospitality operators seeking a reliable, permanent solution to the ventilation-security trade-off. For renters, the installation is non-destructive enough to be reversed when moving out, making it practical for tenants who want better security without permanent modifications to the property. Hotels, guest houses and Airbnb hosts in warm climates have also adopted the device to give guests the option of sleeping with windows open without compromising property security.
The full range is available at the LockLatch® online shop, with free shipping on orders of three or more units. Each product ships with all necessary fixings and a lifetime guarantee as standard.
