Introducing Convex–Concave–Convex, a custom-built home example by AS IT IS Co., Ltd., a Construction company in 576 O, Tsukuba City, Ibaraki Prefecture, Japan

The client initially hoped to purchase and renovate a traditional Japanese house (kominka) to live in, but was unable to find a property that met the requirements and therefore changed strategy to purchase land and build a new house.

Since the house was to be newly built, the brief developed into a desire for a unique, joyful and exciting residence: an entrance whose location is not immediately obvious? A nook? How to relate to the garden? Vertical spatial transitions as well? A looped circulation route!

Although the requests continued to expand, there remained a core desire—"We do not want a large house; we want to relax in a sunny spot"—and the planning proceeded with the primary focus on how to incorporate both aspects.

Because the neighboring property to the south has its living room facing and opening toward this site, we carefully planned the arrangement of rooms, decks and openings so that both households could live without feeling inhibited by one another. We also embraced the agricultural landscape that unfolds to the west of the site. From the outset, to connect vertical spaces seamlessly while ensuring comfortable living—particularly in terms of the thermal environment—we planned with exterior insulation, high airtightness and a skip-floor (split-level) configuration in mind. Warm air from a floor-mounted air conditioner is used to heat the subfloor, aiming to mitigate winter cold in the sunken living room, kitchen and children's bedroom.

Envisioning a close-knit family living together warmly, the result is a dwelling whose interiors convey the organic warmth of natural materials rather than an urban, inorganic aesthetic. Structural type and scale: Timber construction, two stories
Total floor area: 119.24 m²