Eco-house Yamanashi - A house for living with the blessings of nature -

Yamanashi City


Eco-house Model Project by the Ministry of the Environment, Japan

“Eco-house Model Project by the Ministry of the Environment” is a project to promote construction of environmental symbiotic houses in the 21st century through leading model houses.
20 municipalities from all over the country are working on the realization and popularization of eco-houses that make the most of regional characteristics including weather and climate, sponsored by the Ministry of the Environment, Japan.
One of the municipalities among the selected applicants is Yamanashi City. In this city, a model house “Eco-house Yamanashi” uses Shirasu-Kabe for its interior and exterior finish.


"Eco-house Yamanashi" is located to the south of JR Yamanashi Station. It is a two- minute walk from the station. The appearance creates a calm and peaceful harmony with the streetscape. Exterior wall: Super Shirasu-Soton-Kabe W (W-121), Kaki-otoshi finish


Yamanashi City is located in the eastern part of the Kofu basin and has beautiful landscapes with vineyards and orchards of peaches and other fruits spreading over gentle slopes along the Fuefuki River as well as flatlands in the south of the basin.

“Eco-house Yamanashi”, built for the Eco-house Project by the Ministry of the Environment, not only has a special structure that makes the best use of solar heat and natural breeze so that people can live comfortably throughout the year in a climate of extreme temperatures without relying on air conditioners, but also utilizes wood biomass as locally produced energy.

In addition, it seeks to an ideal form of housing where people can enjoy the lifestyle of the next generation with such benefits as a private vegetable garden.


Left: The living room on the 1st floor: a kitchen-dining room is arranged in the center of the house based on the opinions of women interviewed. The layout enables you to listen to and interact with your family.
Right: The entrance: it provides a comfortable openness inviting neighbors for a small chat.
Interior wall: Nakagirishima-Kabe Light in Biocera color LB-72; Kotenome finish



Mr. Oka from Environment Division of Yamanashi City Office said,

“Emissions of CO2 from general households have increased more than 40% compared with 1990. The Eco-house Project by the Ministry of the Environment focuses on CO2 emissions from households. For Eco-house Yamanashi, we tried to understand regional features by making the best use of air circulation and sunshine; we are trying to demonstrate something only Yamanashi City can do.
We minimize regulatory systems and allow individuals to select various ecological technologies, from simple to advanced, for their own houses by introducing plenty of ingenuity.” 


Eco-house Yamanashi uses Shirasu-Kabe for both interior and exterior walls. Mr. Oka tells us why they selected Shirasu-Kabe,

“Mr. Hoshino, designer of the house, mainly selected the materials. He selected materials while considering their effectiveness for the whole house to utilize solar heat and for the air to circulate smoothly, which is different from the conventional concept of heating each room independently.
Since Yamanashi is in a basin, humidity in the summer is very high. In addition, temperature changes throughout a single day are extreme, so it is important to regulate humidity.
Mr. Hoshino recommended Shirasu-Kabe, explaining that it was a natural material and had a humidity regulating function; so we accepted his proposal.” 

Shirasu-Kabe is also effective in preventing sick house syndrome and the synergistic effect together with other natural materials provides a healthy and comfortable living space.

Mr. Oka told us why they participated in the project and how they will utilize the model house,

“Yamanashi City has been promoting this new energy project for more use of natural energy including solar power, hydraulic power, wind power and biomass in place of fossil fuels since 2005. However, energy use in general households is not included in the regulatory considerations.
Then, we wanted to integrate various energy projects. Through proposing the model house, we hoped general households would be included in the integration and take part in this project.
We will utilize this model house mainly as an exhibition hall for people from inside and outside the city to come to witness the new concept.”


Left: One-tubo study which you can use in a traditional way while looking at a Japanese-style garden.
Right: The living room with soft sunshine coming through the shoji screen, which shuts out stronger sunlight in the summer and seals in warmth in the winter.


Paths of wind and light

The window at ground level, the open ceiling space with lattices, and the staircase provide air circulation. They regulate temperatures in the house as well as bring in light.


Mr. Masao Hoshino (architect, Mei Kenchiku Kobo, Fuefuki City in Yamanashi Prefecture.) designed the model house and explained the roles of Shirasu-Kabe for Eco-house Yamanashi:

“When you think about an eco-house, it is important to define what “eco” means. There are many approaches to “eco”. One of them is the selection of materials. Generally, the use of natural materials may be considered as “eco”. However, I don’t think this is enough.

“Eco” should let the functions of natural materials work effectively; so we selected Shirasu-Kabe because it allows us to enjoy the functions of nature. Before Shirasu-Kabe we used diatom earth. However, it had several problems. For example, I didn’t know where it was from; it contained various foreign matters; and some vendors could not even tell me the raw materials used in it. From my experience with various materials, I decided on Shirasu-Kabe; up to now, it has been the best material to use.” 

Mr. Hoshino explains the design concept of Eco-house Yamanashi, “Eco-house Yamanashi is a building based on

the regional features of Yamanashi City including climate conditions. Since Yamanashi is in a basin, the temperatures go up during the day in summer and go down at night. So, we incorporate the idea of using coolness at night to cool hotness during day. This way we tried to wisely utilize regional features to reduce the energy used in air conditioning. This approach can apply to any location within the prefecture. Furthermore, I wanted to go further, to make a proposal of an ecological way of living for people. Therefore, communication is another important design concept for this model house. In order to promote communication among family members, I proposed a layout that avoided children from shutting themselves in their rooms. In addition, for better communication with the local community the house has an openness to indicate ‘living signs’. Thus, the entrance has a substantial space to invite others for casual conversations. I think the layout is a part of communication. I hope these concepts help people communicate with the Earth and make contact with the Earth in a more gentle manner.” 

This Eco-house is filled with many thoughts of Mr. Hoshino.



The appearance of the house makes for an exquisite harmony with the streetscape of Yamanashi City. When you open the entrance door, comfortable air runs gently through the rooms.
Shirasu-Kabe is only one of the elements with which Eco-house Yamanashi utilizes natural power well. However, the effects of natural materials including Shirasu-Kabe promise a cool and contented living space in the unpleasant summertime peculiar to the basin.

Why don’t you learn more about eco-houses from the appealing Eco-house Yamanashi?

Eco-house Yamanashi: sophisticated, eco-friendly elements

Upper left: Circulating warm air is also guided under the floor; it is taken into the room through the slits on the floor.
Upper middle: LED lamps have a long life with smaller electricity consumption.
Upper right: Rain water is stored in the wine barrel; it is used for watering the garden, etc.
Lower left: Light and breezes go through the floor.
Lower middle: Woods produced in Yamanashi Prefecture and specially dried woods, Hagarashi, (dried with branches/leaves in forests for 3 months) are used as structural and finishing materials.
Lower right: Solar Eco Cute is a hot water supply system that utilizes solar energy.


Eco-house Yamanashi: Design concepts and environmental considerations

Yamanashi City is located in the northeast part of the Kofu basin; its climate is peculiar to a basin with intense heat in the summer and cold weather in the winter; the temperature can change dramatically in a single day; however, the daylight hours are longer than many other areas. The design makes the most of these advantages.
In winter a “heat storage floor” of the direct gain type using solar sunlight is the main source of heating; in case of bad weather or lower temperatures an “FF-type pellet stove” using fuel made from mill ends or forest thinnings supplements the system. In addition, air is circulated by means of ceiling fans and circulation ducts in order to equalize the room temperatures.
In summer the windows are covered to avoid sunlight. The cool air in the morning and evening is taken into the rooms to keep it cool by closing the windows during daytime to shut off hot air. In spring and fall when the weather is mild, the windows are opened for natural air flow using gravity ventilation from the lower windows at ground level to the monitor room. Furthermore, the house is designed to have a function to regulate humidity, because pure woods are used on the surface and other humidity adjusting natural materials are used including wool insulation material, Shirasu-Kabe, Japanese paper walls and others, so that a uniform level of humidity can be kept within the house. 


Eco-house Yamanashi

1246-1, Kami-kanogawa, Yamanashi-City,
Yamanashi Prefecture, Japan
ZIP 405-0018
TEL : +81-533-22-5001
Open: 9:00 am to 5:00 pm (admission free)
Closed: Wednesday (if Wednesday is a holiday,
the next business day we will be closed)
*No reservation is required.
However, groups should make reservations.
TEL : +81-533-22-1111 Ext. 2133
Environment Division: New Energy Promotion Group


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