Roof and the wind

Last Uploaded: July, 2008


Plane elevation showing layout of each floor (Q1)

Special Features

Q-1 Comfortable, Healthy, Safety Indoor Environment	Since the shape of the site dictated a long, narrow floorplan on a north-south axis, difficulties were foreseen in bringing light from the south side into the interior of the house in winter. On the precondition that natural energies would be used effectively as a heat source, the southern ridge of the large gabled roof was lowered and high sidelights installed. This made it possible to bring light from the south side into the back of the north-facing rooms. Luckily, the adjacent land on the western side consists of vegetable fields, and we therefore installed as many multiple windows as possible to ensure an effective intake of sunlight in winter. All of these openings consist only of aluminum sashes plus double glazing; the design enables both heat and sunlight to be regulated by the use of wooden lattices, rain shutters and internal screens. The measurement of the eaves overhang was also calculated from the height of the openings and the angle of sunlight in summer and winter. To ensure that the openings function adequately for ventilation, meanwhile, we placed priority on installing terrace doors on both south-facing floors as far as possible, and floor-level windows on the north side. The high sidelights function as heat releases for the lantern (monitor roof). Having rigorously applied this basic principle, the other openings function to provide additional ventilation. In summer, the house is equally open to fresh air at night. Of course, crime prevention measures during sleeping hours could not be overlooked. We dealt with this by making the ventilating rain shutters lockable from the inside, while other openings all have grilles for this purpose. Having chosen sunlight and fresh air as natural materials for creating an indoor heat environment, we then had to be sure of using natural construction materials in spaces that are in contact with these. Here, we placed priority on selecting natural materials, including the paints used for finishing. We avoided the use of plywood as a foundation material, and rigorously applied the use of bare floorboards and wooden slats. Although a certain amount of plywood was used for fixtures and fittings, our standard specifications involved the use of F and wiping off with non-additive plant oil.
Q-2 Sustainability to Service Life	Having confirmed the existence of stable supporting bedrock supported by Kanto loam as a foundation for housing land, we decided on concrete laid foundations. Of particular note were the utility piping sleeves. For ease of maintenance as well as future changes in ground height, we used no slabless underground piping at all. The sleeves were all laid in continuous risers, and the underfloor piping was buried underground on the exterior. Also, to make the underfloor space even drier while taking all measures to prevent humidity around the foundations, we filled it with non-woven fabric bags containing charcoal. Above these we laid a platform of Aomori hiba wood over an intermediate packing layer set in the crown of the foundations. All pillars on the platform were based on long mortise and tenon joints piercing through the platform, and we used law-compliant metal fasteners after driving in hardwood pins. This process was applied to all remaining parts of the framework, in which the standard specification was to apply “wood-on-wood” timber jointing in structural design. Owing to cost considerations, we abandoned the idea of using Japanese pine for the horizontal members, while 80-year-old Kishu cedar was obtained for all pillars. Since the entire framework structure is also a breathing body, we made exposure of the frame a design prerequisite when composing spaces, by creating an external ventilation structure with exposed timber walls on the interior. In any case, the basic principle of our design was that the framework must fully guarantee the longevity of the structure.
Q-3 Regional Contribution for View and Ecology	The land planned for the construction was a subdivided lot from existing housing land, and the name of the titleholder had already changed. A public road lies to the east, but the front of the house does not directly face the road since it lies at the end of a narrow approachway (a so-called hatazao or “flagpole” plot of land). The benefits of a natural setting surrounded by flourishing green hedges and other trees, as garden space from the existing housing land, undoubtedly held the key to creating scenery. Seen on paper, the garden was obstructed by a visible straight line in the form of its boundary, but we carefully planned the arrangement while making the ecosystem of this existing garden continue unmodified into the design of the house. For the shape of the building, similarly, we decided on a simple shape with a large-gabled roof that would not cause any disharmony with surrounding houses, and at the same time would not spoil any of the local greenery. Since the adjacent land on the western side consists of vegetable fields, this is an ideal location for symbiosis with wild birds and insects. We once again felt very strongly that the basic and unavoidable condition for creating favorable urban dwelling environments lies in protecting and preserving such flourishing ecosystems.
LR-1 Saving of Energy and Water	We placed utmost priority on avoiding the use of special mechanical devices; the shape of the structure itself would promote effective use of natural energies, particularly sunlight and fresh air. This passive energy conservation was pivotal, and it would be no exaggeration to say that the format of the building was also designed to support the functions of this passive device. We endeavored to make this a central issue in our design work. However, there is undeniably a weakness, in that it has not been easy to convert the effects of this energy conservation into numerical data. Inevitably, therefore, the evaluation here, which is based on numerical data to a certain extent, will be low. We would like it to be taken into account, as a matter for self-evaluation, that the operating ratios of mechanical equipment have been reduced. Our basic rationale is to use energy-saving equipment for gas, electricity and water supply, such as equipment and appliances using city gas, or household electric appliances. However, these must never be seen as playing anything more than supplementary roles in supporting the passive energy conservation measures. For ventilation equipment, etc., we used localized mechanical ventilation (Type 3), bearing in mind that the house itself should provide its own ventilation functions. In fact, the whole house could be seen as a spatial device designed for natural ventilation.
LR-2 Resources and Materials	Here, our brief is to use natural materials as they are and return them to the earth intact. Including the problem of CO₂ emissions, this is by no means easy. For the time being, therefore, all measures here should be prefaced with “as far as possible”. As an effort in this respect, we adopted the standard specification of using timber from planned felling in both Japan and abroad for the structural skeleton, which occupies the greatest weight in terms of timber demand. Of course, we also take the selection of the type of timber into account here, i.e. choosing the most appropriate materials for each location with a view to prolonging their useful life. As a direct measure for waste, we rigorously apply measurement design with the aim of improving the yield rate of the timber used. By using a downscaled module calculation, from the stage of basic design, to ensure that no discrepancy in pillar locations occurs between upper and lower floors, we can considerably reduce the amount of material wasted. Besides this, when creating specifications we also attempted to increase the variety of common finishing materials, avoid the use of secondary timber processed products, etc. In future, we will need to make practical design proposals aimed at further reducing the use of mechanical equipment.
LR-3 Contribution for Environment of Earth, Region & Town	The surrounding area consists of tranquil, mature urban housing land blessed with abundant greenery. Some districts have a plot size of more than 100 tsubo (ca. 400m²) per dwelling, and although these are now being subdivided into smaller lots owing to various pressures, a variety of green hedges and trees still provide shade for the streets and urban area. Needless to say, the shape of the house itself was subject to the pre-existing design conditions of maintaining the rich plant ecology existing within the site. First, we created a layout plan in which the conventional green hedges that have long existed in this district were left intact, and retained the plants and trees that already existed in the garden. Next, we overlaid the housing program over this. Even then, we had no choice but to transplant some plants, though only inside the site area. A large chestnut tree stood on adjacent land to the north. We attempted scaling in order to balance the house with this tree. Our simple intention was to harmonize the neutral color of the house and the natural tones of the wood with the “green” color of this district. Also, to create design specifications that were completely flat and seamless on all elevations, we set out to make outdoor equipment and appliances, in particular, completely built-in.

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These cases are described based on assessment results obtained using CASBEE.
CASBEE is a method for rating the environmental performance of buildings using Building Environmental Efficiency (BEE) as an indicator, which is based on the results of separate scores obtained for Q-1~Q-3 (Quality) and LR-1~LR-3 (Load Reduction).