Episode
The site is located in a quiet residential neighborhood in the city center, with a narrow, sloping terrain that rises towards the rear of the lot while also descending to the east. The elevation difference is as much as 5 meters, with apartments overlooking the southern side, and a retaining wall of a collective housing structure built right at the boundary on the west side. Though the client had relatively few specific requests, there were stringent conditions such as complex zoning regulations and the need to meet area requirements, making the design challenging.
The key requests were as follows:
To create a spacious, bright, and comfortable living space that feels open and without a sense of enclosure.
Despite the narrow frontage, accommodate two cars for parking.
Maximize the usable area as much as possible.
Provide a calm and peaceful space for listening to music.
Planning
To maximize the available area, a basement was included in the design. However, except for the top floor (second floor), all living spaces would be located underground. Rather than viewing the underground as negative, we drew inspiration from natural valleys and aimed to create a space where calm, poetic light would cascade into the basement.
Conversely, the second floor was designed with a sloping roof to maintain privacy while incorporating a combination of skylights and high side lights. The southern garden, as well as a rooftop garden on the northern side, were added to create an open, airy atmosphere, like a treehouse, where both natural light and ventilation could flow freely. This design concept establishes a contrast between the upper floors and the basement, creating a sense of height and depth akin to a natural valley.
Valley-like Staircase Hall
The staircase hall was designed to follow the slope of the site, allowing for a reduction in the amount of earth that would need to be excavated for the basement. This consideration also made the construction process more efficient. The six "skipped" living spaces are continuously connected without interruptions. Through a 10-meter high vertical stairwell, natural light from the top and side lights on the second floor gradually illuminates the basement, creating a beautiful gradient of light.
Treehouse-like Openness
The living-dining area, which has a dome ceiling, features a skylight at its center, helping to regulate the temperature of the continuous space. The ceiling slope naturally rises in alignment with the slanted site, leading to a high side light that reflects light. On the southern side, the area is overlooked by neighboring apartments, so we designed the space to maintain privacy while achieving an open, spacious feel. The eaves were kept low, and the sloped terrain was left as a terraced garden. Furthermore, the top floor was made into a single open floor with only partial glass partitions, which allows views to extend freely in the long direction, enhancing the openness.
Environment
Given that half of the three-story building is underground, we took advantage of the environmental differences from the basement to the rooftop and controlled these elements effectively. The ventilation system, which circulates through the atrium connecting the basement to the top floor, uses natural air intake from the bottom steps of the underground staircase and near the skylight on the second floor. The system can reverse airflow during summer and winter, promoting an optimal thermal environment. Additionally, underfloor heating in the basement, embedded in the concrete slab, absorbs heat to address the humidity and coldness of the underground space. These combined methods help regulate localized environmental variations in the large, continuous space.
Rather than considering the underground space as a negative element, it provides a cool, stable year-round environment, especially beneficial in the hot summers. Looking up from the basement toward the sunlight filtering through the top floor’s windows feels like being at the bottom of a valley, providing a sense of calm. The lighting plan for the basement was designed not to be overly bright but to maintain a natural, gentle glow. The colour scheme gradually shifts from darker tones in the basement to lighter hues and materials as you ascend to the top floor. This gradient effect brings both light and shadow into focus, making the entire house feel balanced between privacy and openness, with an emphasis on the natural environment.
