The Ecotone Hotel

The project is a hotel on the shores of Biwa Lake, the largest lake in Japan. The design intent was to revitalize the site’s Ecotone (a transition area of vegetation between two different plant communities, in this case water and land) that has been damaged by rapid, economic-driven development while utilizing the abundant potentials of the site, incorporating them into the design.

The initial approach was to make the building a part of the ecotone. RAA also aimed to strengthen the relationship between residents and nature. As a result, the project proposes a respectful architecture concerned about both the environment and the society. Locally sourced soil materials, techniques & craftsmen were employed in the design and applied throughout the hotel. Moreover, years after completion, the husbandry on site is still taken care of, actively involving the local community in the restoration effort.

Climatic potentials were utilized in passive design schemes. Green roofs become platforms that allow the surrounding natural vegetation to thrive. Rainwater is collected from the roof and distributed into the ponds through the biotopes, purifying water for on-site aquatic life. This collected water evaporates then cools the building.

The use of local soil material & technique proved to be superior in terms of environmental performance and ecological footprint. The structure and earth walls reduces cooling load by 70%, rendering air-conditioning unnecessary when outside temperature ranges from 18 to 28 degree Celsius. During winter, heat is stored in the earth walls, warming up the rooms at night.

Wind from Lake Biwa flows through the building travelling from north to south, this is achieved by changing the angle of the wall extending from east to west. Reinforced concrete slabs, like folded plates, supported by oblique pillars aim to create a space where structural beams are invisible; the slab’s unique shape can only be perceived from the spaces below where the concrete is exposed. The slab shape also plays the role of eaves, controlling solar radiation. The uppermost slab works as a green-roof where the surrounding natural vegetation continues growing.

Sound of Wind, a chapel adjacent to the hotel, is a musical instrument that captures the potential of the site. The lake’s wind flow is converted into sounds by using Aeolian harp strings. The chapel becomes a gentle space that echoes the sounds of the lake, where one can appreciate nature in its full extent through the sensory experience.

Inside the chapel a series of 0.72 mm SUS wires are placed; when the air flows over them, they resonate similar to the strings of a harp, producing a beautiful sound. The speed of wind can be altered by a set of apertures at the east and west side of the building. These apertures can be operated, altering the tone of the sounds.

A comprehensive analysis of the exterior shape, the interior space, as well as the direction, speed and frequency of winds was undertaken in the development of the project. Three hundred different computational fluid dynamic simulations were analyzed to refi ne the building shape, and several mock-ups were built in order to assess the wind fl ow inside the space. After this iterative design process, and once the basic shape had settled, a 1:10 scale mock-up was tested both in a wind tunnel and on the project site. The whole process being carried out in close collaboration with sound artisans, and specialists in the field of wind music instruments.

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