Homes can be expensive in Beijing, China.

A design firm in the area, called People's Architecture Office (PAO), heard from a woman who was struggling to afford a home, and had taken to living in a small, dilapidated house in the courtyard of her parents' residence outside the city.

Fed up with the poor conditions, Mrs. Fan (who declined to give her full name for privacy reasons), commissioned PAO to build her a new home.

The architects designed what they call a Plug-in House for her in December 2016.

With just $10,000 worth of materials and a hex wrench, a construction team can build the Plug-in House in less than 24 hours, PAO's principal, James Shen, told Business Insider in March. The firm based the design on a similar one it used to create a renovation system that consists of locking pre-fabricated panels.

In July 2017, the Plug-in House made the shortlist for the World Architecture Festival's World Building of the Year award. The winner will be named at the festival in Berlin in November.

Check out the Plug-in House below.

The Plug-in House is located in Changchun Jie, a small town outside Beijing.

Image: People's Architecture Office

Mrs. Fan lives there with her son. The one-story house they used to occupy on the site was demolished before the Plug-in House's construction. Here's a before and after.

Image: People's Architecture Office

The Plug-in House is much more modern.

Image: People's Architecture Office

It features a kitchen that connects to a living room, two small bedrooms, and a bathroom.

Image: People's Architecture Office

The interior lets in a lot of natural light.

Image: People's Architecture Office

Even the shower has a skylight.

Image: People's Architecture Office

Steps on the side of the house lead to a roof deck.

Image: People's Architecture Office

Almost anyone can construct a Plug-in House. "The structure is built without any machinery and does not require specialized labor," Shen said.

Image: People's Architecture Office

The house is made of dozens of panels that get connected with one tool: an Allen wrench (also known as a hex key), which is the same tool used to assemble Ikea furniture.

Image: People's Architecture Office

The custom-size panels are cut off-site to reduce cost.

Image: People's Architecture Office

PAO created the construction system for another project, called Courtyard Houses. For that 2016 project, PAO renovated 20 homes outside Beijing that lacked basic amenities like insulation, sewage lines, and sometimes kitchens and bathrooms.

Image: People's Architecture Office

The Courtyard Houses project was subsidized by the Beijing government and involved renovating existing structures, not building a new one.

The first Plug-in House was funded by Mrs. Fan, and PAO has since built a second one, also near Beijing.

Shen sees the project as a low-cost housing solution. "Because the Plug-in House can be conveniently flat-packed, shipped, and put together, we can build it in remote locations that are usually difficult to build in," he said.

Image: People's Architecture Office