old public bus in japan transforms into mobile sauna to travel across hyogo prefecture

introducing the ‘sabus’ mobile sauna

Osaka-based architecture firm OSTR has teamed up with Japanese start-up Sauna Ikitai to transform an old bus into a mobile sauna that travels around Hyogo Prefecture. The vehicle, named ‘Sabus,’ combines the renovated bus and a newly installed bathtub, while the confinement and new layout of the space allow users to choose between different heated areas. Wooden seats and padded benches provide comfort, and large windows help passengers connect with nature while enjoying the wellness benefits of the sauna.

the exterior of the bus is mostly left unchanged | images courtesy of Sauna Ikitai, Oosuke Otake

turning disadvantages into advantages

The ‘Sabus’ project began when the Japanese startup Sauna Ikitai commissioned the OSTR architectural firm to renovate the disused bus and transform it into a functional sauna. The Osaka-based architects mainly focused on the fitting of the wood-fired sauna because the movement of the bus posed certain limitations in terms of the load it could carry. This installation was particularly difficult because the regulations for bus conversion differed from those for buildings, and there were also no suitable plans for existing buses.

The architects approached the project much like renovating a building, considering the context. The confines of the bus, which would otherwise be perceived as a ‘disadvantage,’ were used for the renovation, allowing a new, multi-level layout to be created in the Sabus. The bus has several levels, each offering different levels of warmth. The first row, where you feel the heat from the stove directly, the second row, which has the highest floor and is closest to the ceiling, and the fourth row, where you can lie down because of the shape of the bench, have the most convection from the ventilation.

depending on the destination of the bus, users can enjoy a sauna surrounded by nature or the city

a sauna moving across japan

The windows were kept as large as possible so that passengers could feel the richness of the movement. Depending on the destination of the bus, users can enjoy a sauna surrounded by nature or the city. The front part of the bus can be used as a rest area and luggage storage in the form of a vestibule. It consists of the original bus interior and the reuse of benches.

As for the exterior, the basic appearance of the bus has been left largely unchanged, although the architects have added some elements to signal the new use. Originally, only an orange line was drawn on the body, but a light blue line was added to express the relationship between the sauna and the cold-water bath. By keeping the same seating arrangement and using the existing windows in the sauna, as well as leaving half of the interior of the bus, the designers thought it would be nice to experience the strange feeling of being in a sauna even though you are in a bus.

the windows were kept as large as possible so that passengers could feel the richness of the movement

repurposing old handrails and buttons

Most of the sauna equipment was made by reusing and remodeling old bus parts. For example, the handrails attached to the seats were wrapped in hemp for a cozier feel, and the lore button doubles as the original ‘get off’ button. The architects also turned the suspension strap into a thermometer and the numbered ticket box into a container for aromatic water.

most of the sauna equipment was made by reusing and remodeling old bus parts