The site of this building is located at Lake Chuzenji in Nikko city. Its lakeshore has been lined up with summer houses of foreign embassies since quite some time ago. The project is to pull down a 5-story recreational facility of a company and build a new, private summer house for an individual client. The building is built as close to the waterside of the lake as possible, while its height is kept low. A two-story building is placed at a location with inclined topography, where its height level goes down from a road to the lakeside in 7m. The circulation of this building is designed to be accessed from the road, to the 2nd floor level provided with a main dining space for welcoming guests, while the spiral configuration of the building gradually leads the guests to the 1st floor level with bedrooms.
The 1st floor plan brings in the lake water to an inner garden by removing the shoreline protection work existed between the lake and the previous building. The scenery of the lake is framed by a 20m long,large spanned floor slab,which extends over the garden area.
最大程度确保湖景的结构设计The structure design to provide the best vista to the lake
The porch area on the 2nd floor continues to the dining space covered with a steel frame cantilevered roof. Considering snowfall on the roof as much as 1.2m deep, the steal beam of the roof is cambered in advance, and sag rods (SUS13φ) are placed in 3m intervals at the roof tip for consistently adding tension to the roof. These structural designs prevent from the deformation of the roof at the time of heavy snowfall, as the tension to the roof is relieved by snow load. The reaction force of those sag rods are taken from the reversed beam of the steel reinforced concrete (SRC), which is utilized for making the eaves soffit of the 1st floor appear straight and flat--therefore those structural designs also reduce the deflection of the long-spanned floor slab at the same time. By managing the deflection of the roof against snow load, it becomes possible to utilize large-sized sashless glasses to maximize the vista to the lake. The glass has the width of 10m for its dimension, while this is the maximum size to carry through the severely winding road of Iroha-zaka sloping road in Nikko city.
利用BIM模型进行的序列研究和热环境模拟Study of visual sequence and thermal environment simulation using BIM model
During the design process, data of the topography and the mountain range around the site was entered to the BIM model in order to study and find the most suitable location of the building for getting the best vista of the surrounding scenery. This model was also used to study the balance of the scale of each room, and the shapes and the heights of the openings in consideration to the visual sequence along with the circulation inside of the building. During the execution design process, more in depth studies were made by using the BIM model for the details of each part of the building, finishing materials, and placement of furniture. This BIM model was further andwell utilized for examining the structure tocontrol the roof deflection under snow fall, and studying the natural ventilation by making use of the continuous spiral space, and simulating the thermal environment of the heat produced by the fireplace in a lounge space with a bar corner.
凉爽怡人气候中，畅享水畔生活的避暑别墅A guesthouse promising a pleasant time by the water in the balmy summer weather
Situated alongside a lake, this guesthouse was designed as a continuous spiral space flowing from the approach to the bedrooms. Each step taken deeper inside the building reveals a changing lakefront view. The various lakeside environments, including the sound of ripples, light reflecting from the water surface, the humidity and thermal radiation, are also carried on into the spiral, but in a non-uniform distribution due to changes in physical distance from the water surface. Since the whole structure is an interconnected space with different elevations, there is no homogeneous environment—various areas present various thermal environments such as the fireplace warmth and the dryness of the air.
Guests wander around in this atmosphere, discovering and enjoying spots they find comfortable. Located in a natural environment that requires a bit of heating in the building even during the summer nights, one may find joy in the warmth near the fireplace, while another may relish the area’s tranquility and cold characteristic. The building is closed during the harsh winter season to prevent any wasteful investment of energy.
This is the kind of hospitality this guesthouse promises to deliver.
Design Team: Tomohiko Yamanashi, Satoshi Onda, Hajime Aoyagi
Total floor area:751.92㎡
Building height: 7.33 m
Structural system:reinforced concrete