The design for this energy efficient private residence with its characteristic form, for a couple with their two young sons, stands out between the ready-made houses that surround it. On a 202 m2 plot in the New Town Tsukuba, developed since the 1960s and now famed for its University and research center, the client sought to build a one story house full of light whilst protective of privacy. A quite contradictory brief and a puzzle to solve. In addition to this the brief required the possibility to use the space flexibly, wheel chair access, a Japanese room and furthermore space for a vegetable garden, parking for 2 cars and 4 bicycle, all on a small budget.
To satisfy the requirements concerning the exterior use of the plot, a square plan emerged that was sized 9.100 x 9.100 or 10 times the current Japanese module for timber structures of 910 mm square as the most adequate solution.
Amongst the housing typologies in Japan the one story house is popular type for its compactness, economy and earthquake resistance. Because of the limited height these houses are less prone to earthquake damage. Also in traditional Japanese architecture this type was widely used and created an architecture dominated by the roof rather than the facades, as is proofed by the two neighboring traditional houses. With this notion in mind the roof design became a major subject of study and led to the characteristic shape of the roof. The idea was developed to use high side windows, often found in museums, at each corner of the house, in order to create an interior with abundant natural light. This strategy proved to be effective in solving the contradictory problem of lightness and privacy.
Therefore four vertical windows of 2. 7m height with light catchers behind, that look like Four Ears one at each corner, protruding beyond the overall height of the house where designed to stand out high against the sky. This way of placing the windows allowed the penetration of daylight deep into the house as well as the blocking of unwanted views into the interior, whilst still providing views of the outside. Through these Four Ears each facing another direction, light is projected both deep into the interior as well as reflected off the white perimeter walls giving the house its lightness.
In addition to this in the middle of the square house a roof light was designed. Much like a pointer, a light beam floats through the center of the space, working together with the four high side windows as a sort of sundial making the progress of time felt throughout the day. The corners of the house light up at different times during the day. To make this effect work to the best the temptation to decide for a house with separate rooms was resisted in favor of an open plan lay-out in which areas were determined by the placing of two square boxes, one containing the Japanese room and the other the wet cell. In addition to this, a storage unit functioning as a screen was placed between the living zone and the sleeping zone. This screen together with two columns compose of a square in the center of the house purposed to be the living area, the core of daily life. All other functions are grouped around this central square. The sleeping zone spans the whole width of the south-west side and can be freely separated into three smaller zones by the movable wardrobes. This solution was developed in response to the request for flexibility and separate sleeping areas for the two children in the future. On the opposite side of the house a long counter with integrated kitchen is designed also spanning the whole width of the house. To add some soft enclosure to this open plan lay-out curtains were used on spanned wire.
Coincidentally the two square boxes are sized 4.5 tatami mats large, exactly like what is considered the ideal size for a Japanese tea room, while the overall layout of the house happens to follow the tatami arrangement of such a tea room. The advantage of this lay-out is that it softens the inherent symmetry of the square and introduces dynamism into the plan. The off-set placing of the two boxes further enhance this effect.
This arrangement is expressed through the change of the direction of the exposed roof beams lay-out as well as in the birch plywood flooring sized and cut to match the module of the house. The walls are a plasterboard neutrally painted in a light gray as to function as the reflector of light.
The facades are clad with Japanese cedar planks of miscellaneous widths applied in an irregular pattern. The 20 mm gaps between the planks are colored differently in red, yellow, blue and green to reflect the corresponding zone of the interior. From a distance the entirety of the house is dominated by the wood slats rather than this color palette, but upon aging and graying of the planks viewed on short distance the color will seep from between the planks adding contrast to the natural material. Topped off with the white Four Eared roof, seamlessly constructed in white FRP (Fiber reinforced plastic) like used in the construction yachts, a contemporary response was found to the need for a characteristic roof form. The two boxes are finished with wood fiber cement board a material often used as substrate.
In addition to the above design rational a strategy towards energy efficiency was executed through high levels of insulation, minimization of glazed areas (only 8,74 % of façade surface), natural cross ventilation, natural light and stabilization of interior temperature fluctuation by the use of the heat mass of the foundation concrete.