Kentaro Imai Architectural office
KAIRYO-YU 2022 Renovation
Kairyo-yu, located in Shibuya Ward, is a Sento that our company was in charge of renovating in 2018. Upon its completion, it received great acclaim, and with the subsequent sauna boom, we faced a situation where entry restrictions had to be implemented due to the large number of visitors wanting to use the sauna. In 2021, the owner approached us with the request, “To alleviate congestion, we would like to expand the men’s bath by utilizing surplus spaces such as under the stairs and storage rooms.” As a company, it is a great honor to be re-commissioned for renovation work within a few years due to the popularity of a Sento we previously renovated. The 2022 renovation of Kairyo-yu marked our company’s first time working on a second renovation project for the same Sento.
The 2022 renovation primarily focused on the men’s bath. The space under the stairs, which had been used as a storage area adjacent to the men’s bath, was repurposed and expanded into an outdoor air bathing area. Additionally, the cold bath was relocated to expand the sauna room, resulting in a reduction in the number of faucets from 16 to 11.
Due to the ongoing sauna boom, interest in the specifications and design of sauna spaces, especially the stove, has understandably increased. The owner had requested the adoption of an electric stove with a löyly function. While electric stoves with a löyly function are common, we faced challenges with increasing the power supply capacity, so a gas-powered stove was chosen for this renovation. Sentos, which use a large amount of hot water, generally rely on gas for heating, making gas stoves a practical choice. However, with gas-powered löyly stoves, it is necessary to install heat dissipation pipes under the bench, which posed design limitations, especially when considering the relationship with lighting. We paid particular attention to the lighting design, aiming to minimize the visibility of other users’ faces and presence, opting for a design that only illuminates the area around the feet.
In the case of Sento saunas, it is still quite rare to have a dedicated outdoor air bathing area. This is because many Sentos in Tokyo have limited space, and even if they do, the space is often used to install open-air baths. Fortunately, Kairyo-yu had surplus space adjacent to the bath, which we were able to utilize effectively. With the rise of the sauna boom, it is expected that requests to create “dedicated outdoor air bathing areas rather than open-air baths” will increase in future Sento designs where there is sufficient space. Outdoor air baths are also much more cost-effective than installing open-air baths due to the reduced need for equipment. In any case, when it comes to Sentos located in urban areas, designs that make the most of even the smallest spaces are essential.
