The silver birch trees of England’s New Forest National Park were a key inspiration in the design of what is effectively a genre-defining mobile home.

The project’s owners, Mel Matthews and her husband, Roy, had lived on five acres of this preternaturally lovely Hampshire woodland setting for 24 years—first in a static trailer and then in an off-the-shelf mobile home—before they finally decided that they’d had enough of cold winters in their poorly insulated park home.

“We looked at larger houses in the area, but we kept coming back to our beautiful site surrounded by bluebell woods and streams,” Mel says. With that in mind, the couple set out to find an architect to build a bespoke house on the site. They found their match in PAD Studio, attracted by the firm’s design approach and Passivhaus principals.

While new permanent construction is prohibited in this protected conservation area, planning permission existed for a mobile dwelling. Following extensive research into the field, PAD Studio designed Forest Lodge: a steel-frame structure featuring an open-plan layout combining living, dining, and kitchen areas, and two bedrooms, one of which doubles as an office.

The house was prefabricated and fully fitted out internally—down to the ceiling fans and limestone countertops—in Yorkshire over the course of five months. It arrived on site in two parts on two flatbed trucks, and was then lifted by crane onto the existing concrete-and-limestone plinth.

At approximately 22 feet wide by 65 feet long, the new house is the maximum size permitted by the UK Caravan Act of 1968, but the structure sits quietly among its surroundings. Clad in chestnut boards echoing the silvery hue of the surrounding trees, the super-insulated house also features large triple-glazed windows strategically placed to allow in light and views. Internally, the restrained material palette provides a backdrop that doesn’t compete with the changing colors of the forest.

Built with rigorous Passivhaus standards in mind, the home also boasts a 3.8-kilowatt photovoltaic array on the roof to generate electricity, and an air-source heat pump that provides hot water for the radiant heating system. Rainwater is harvested from the roof, which also features structural eyelets so a crane can lift the structure from its concrete mooring, should Mel and Roy ever want to (literally) pick up and leave.

For the time being, though, they’re going nowhere. “It may be built to a restricted size, but we don’t feel it’s a compromise,” Mel concludes. “It suits our needs perfectly.”