On a small strip of land tucked away in a corner of York, UK, sits a dark grey metal structure about the size of a shipping container. Two security cameras are trained on four numbered doors running across the front. Each secured by a keypad, the doors open into small, modest rooms equipped with a single bed, a toilet and a sink. They might not look like much, but these "nap pads" are the first of their kind in the UK, containing technology that could save the lives of hundreds of homeless people – and keep many more off the streets in the winter. Charities like the Salvation Army have worked tirelessly to end the scourge of homeless deaths, most of which are preventable. The challenge has always been providing somewhere warm and dignified while also ensuring people are safe. Working with service users and tech developers on the design, the Salvation Army came up with "nap pads": containers that not only provide a warm place for homeless people to sleep, but can also track the vital signs of those using them.