The Hokuriku region of Japan, facing the Sea of Japan, records more rainy days than any other region in the country. Architects working in this climate have developed building strategies over centuries that manage moisture, capture available sunlight, and create comfortable living spaces despite challenging weather. These passive environmental control methods rely on building orientation, roof geometry, and transitional spaces rather than mechanical systems. The House in Kanazawa, completed in 2019 by Shota Nakanishi Architects and structural engineer Hirofumi Ohno, demonstrates how traditional Hokuriku architectural principles can be reinterpreted for contemporary residential design. This project earned a Highly Commended rating in the AR House Award 2021 from The Architectural Review, drawing attention for its thoughtful integration of regional building traditions with modern program requirements.
Understanding Hokuriku Architecture and Its Climatic Context
Hokuriku architecture developed in response to one of Japan’s wettest climates. The region spans Ishikawa, Fukui, Toyama, and Niigata prefectures along the Sea of Japan coast, where winter brings heavy snow and persistent cloud cover, while summer delivers monsoon rains and high humidity. Buildings in this tradition share several defining characteristics that manage these conditions without relying on modern HVAC equipment.
Key Characteristics of Traditional Hokuriku Buildings
| Feature | Function | Modern Application |
|---|---|---|
| Deep eaves and large roof overhangs | Protect walls and openings from rain and snow | Extended roof lines in contemporary homes |
| Doma (earth-floor transitional space) | Buffers between exterior and interior conditions | Indoor garden rooms and sunrooms |
| Sliding shoji and fusuma screens | Adjustable light, privacy, and ventilation | Large sliding glass panels with adjustable shading |
| Raised wooden floors | Isolation from cold, damp ground | Radiant-heated slab floors or ventilated crawl spaces |
| Verandas (engawa) | Sheltered outdoor circulation and connection | Covered patios and transitional zones |
The connection between heritage conservation and passive house design has grown stronger as architects recognize that traditional builders solved many of the same problems that modern energy codes address. In Hokuriku, the traditional farmhouse known as gassho-zukuri features steep thatched roofs that shed heavy snow, deep eaves that keep summer sun off walls, and an open floor plan that allows cross-ventilation. These same principles reappear in the Kanazawa house, adapted to a narrower urban site and contemporary construction methods.
The Doma as a Transitional Indoor-Outdoor Space
The doma is one of the most distinctive elements of traditional Hokuriku architecture. Historically an earthen-floored area at the entrance of a farmhouse or merchant home, it served as a work space, a reception area, and a buffer zone between the outdoors and the raised wooden interior. In the House in Kanazawa, the architects reimagined the doma as an indoor garden positioned under a large roof that captures and distributes sunlight across the living areas.
How the Modern Doma Functions
The contemporary doma in the Kanazawa house occupies the center of the floor plan rather than the edge, acting as a light well and visual anchor for the entire home. Its key functions include:
- Light distribution: The large roof above the doma captures morning light and channels it deep into the interior, reaching rooms that would otherwise depend on artificial lighting during daytime hours.
- Seasonal temperature buffering: The space absorbs solar heat in winter and vents hot air through openable glazing in summer, stabilizing indoor temperatures without mechanical intervention.
- Visual connection to weather: Large fittings separate the doma from interior and exterior spaces, allowing occupants to see and hear rain, wind, and seasonal changes while staying protected.
- Social gathering area: The doma accommodates the traditional Japanese function of greeting and interacting with guests, maintaining its cultural role while taking on new architectural form.
Acoustic Separation through Layered Openings
The sliding fittings that define the doma perimeter serve an acoustic purpose as well as a visual one. The architects designed these assemblies so that the sound of wind, rain, and thunder reaches the interior as a distant sensation rather than a direct disturbance. This layering effect makes the weather visible and audible at a comfortable remove, allowing residents to enjoy the sensory richness of the changing seasons without the discomfort of exposure.
Passive Solar Design through Seasonal Light Management
The Kanazawa house demonstrates how roof geometry and opening placement can replace or supplement mechanical heating and cooling. The large roof over the central doma was calibrated to admit direct sunlight at different angles depending on the season. In summer, when the sun tracks high across the sky, the roof overhang blocks direct radiation from entering the living spaces. In winter, when the sun sits lower, the same geometry allows beams to reach deeper into the interior, providing passive heating.
This seasonal light management is a direct translation of traditional Hokuriku eaves into contemporary form. The relationship between heritage conservation and high-performance design often hinges on simple geometric decisions like roof overhang depth and glazing orientation, choices that cost little at the design stage but deliver energy savings for the life of the building.
Calculating Overhang Depth for Passive Solar Control
| Latitude | Summer Solstice Sun Angle | Winter Solstice Sun Angle | Recommended Overhang Depth (for 2m tall window) |
|---|---|---|---|
| 35°N (Kanazawa) | 78° | 31° | 1.2 m |
| 40°N (Tokyo) | 73° | 26° | 1.5 m |
| 45°N (Portland, OR) | 68° | 22° | 1.8 m |
| 50°N (Vancouver) | 63° | 17° | 2.2 m |
At Kanazawa’s latitude of approximately 36.5°N, the architect specified deep overhangs comparable to the recommendations above. This ensures that direct summer sun never strikes the main glazing, while winter sun enters freely. The approach reduces cooling loads by an estimated 20-30% compared to a building with the same glazing area but no overhang protection, based on data from passive solar building studies in comparable climates.
Layered Architectural Assemblies for Environmental Control
Rather than relying on a single building envelope to manage all environmental conditions, the House in Kanazawa employs multiple layers of assemblies, each serving a distinct purpose. This stratified approach mirrors traditional Japanese construction, where exterior walls, sliding screens, verandas, and interior partitions each contribute different levels of enclosure, ventilation, and light control.
The outermost layer consists of the large roof and the primary exterior walls, which shed rain and provide thermal insulation. Inside this shell, the doma functions as a second environmental buffer. Within this buffer, the individual rooms are defined by additional sliding partitions that can be opened for cross-ventilation or closed for privacy and thermal separation. The way civic design integrates with passive house principles often follows a similar logic: multiple layers of environmental management rather than a single sealed envelope.
Step-by-Step Process for Layered Envelope Design
- Identify prevailing wind and sun paths for the specific site. This determines where openings should be placed for natural ventilation and where roof overhangs must be deepest.
- Define the primary envelope: The insulated, weathertight shell that meets energy code requirements for thermal resistance and air sealing.
- Create one or more buffer zones: Spaces like the doma, a sunroom, or a covered veranda that sit between the exterior and the conditioned interior. These zones reduce heat loss at the perimeter and pre-condition incoming air.
- Design adjustable interior partitions: Sliding panels, curtains, or folding screens that allow occupants to manage privacy, airflow, and daylight room by room.
- Coordinate roof overhangs and shading devices: Fixed overhangs for seasonal solar control, supplemented by adjustable blinds or screens for fine-tuned light management.
Materials That Support Layered Construction
The materials chosen for each layer affect its performance. The primary envelope in the Kanazawa house uses modern insulated wall assemblies comparable to standard Japanese residential construction. The doma layer uses large-format glass and timber framing that allows high light transmission while providing shelter. The interior partitions employ lightweight wood and paper or fabric screens that allow air movement while defining space. Each material was selected for its role within the specific layer rather than optimized for a single performance metric.
Designing for Emotional Connection to Place and Season
The client brief for the Kanazawa house requested a home that makes residents want to return to it, not through luxury finishes or dramatic design gestures, but through the accumulation of pleasant daily experiences tied to the changing seasons. The architects responded by creating spaces where the passage of time and the character of each season become visible and tangible within the home. This approach has direct parallels to how architects apply passive house design principles to create comfortable spaces that respond to natural cycles.
How Seasonal Experience Manifests in the Design
- Morning light patterns: The large roof directs morning light into the central doma, creating a dynamic play of shadows and brightness that shifts throughout the year as the sun path changes.
- Rain and snow as spectacle: Weather events that would normally keep occupants indoors become visually engaging experiences viewed from the protected doma.
- Temperature variation within the home: Rather than maintaining a uniform temperature throughout, the layered design allows warmer areas near the doma and cooler areas deeper in the plan, giving occupants choice about their thermal environment.
- Plants and seasonal greenery: The indoor garden of the doma changes with the seasons, bringing living greenery into direct contact with the interior.
Quantifying the Emotional Impact of Biophilic Design
Research on biophilic design (the practice of connecting building occupants with nature) shows measurable benefits. A 2019 review in the journal Building and Environment found that access to natural light, views of vegetation, and the presence of natural materials in buildings reduced occupant stress by 15-20% and improved cognitive task performance by 10-25%. The Kanazawa house delivers these benefits through its doma garden, natural material palette, and the visual connection to weather patterns that the layered envelope makes possible.
Applying Traditional Japanese Climate Strategies to Modern Homes
Architects working outside Japan can adapt the principles demonstrated in the Kanazawa house to their own climates. The core concepts (transitional spaces, layered enclosures, seasonal light management, and emotional connection to place) are universal design strategies that do not depend on a specific construction system or material palette. The integration of passive house standards with sustainable urban design represents a parallel movement that shares these goals, using quantified performance targets to achieve similar outcomes.
For a home built in North America or Europe, the doma concept might translate to a south-facing sunroom or a buffer space between the garage and the main living area. The layered envelope approach might mean designing a porch or veranda that protects the main walls from rain and sun, combined with operable interior partitions that allow flexible room configurations. The attention to seasonal light patterns might mean modeling sun angles at the design stage to determine optimal window placement and overhang depth, using free tools such as the Solar Tool or Ladybug for Grasshopper.
The result is a home that performs well thermally while also enriching the daily lives of its occupants through sensory engagement with the natural world. The Kanazawa house shows that these goals are compatible, and that traditional regional architecture holds lessons that remain valuable in the age of high-performance building standards.