Portland Japanese Gardens

Portland, Oregon

Environmentally sensitive expansion respects Japanese Gardens’ rich legacy and updates vision

Designed by world-renowned architect Kengo Kuma, whose work includes the $1.5 billion National Stadium for the 2020 Olympic Games, the Portland Japanese Garden’s new Cultural Crossing Village includes three new pavilions and a courtyard that honor the tranquility and beauty of the surrounding gardens. The $33.5 million project includes space for traditional Japanese performances such as Kabuki theater, gardening demonstrations, art and cultural displays, a library, tea café, and gift shop.


  • The Challenge

    To accommodate rapid visitor growth and offer an immersive experience in traditional Japanese arts and culture, the project added 3.4 acres, pavilions, and a courtyard on steep terrain. Kuma is one of the most significant contemporary Japanese architects today, and the project needed to maintain the integrity of his design, remain durable enough to support hundreds of thousands of visitors from around the world, and incorporate sustainability.

  • Our Approach

    We initially enhanced the design process by staging a sustainability workshop at the project’s inception for various members of the design team, representatives from the board of directors, and project consultants. Orchestrating the interactive brainstorming session, we discussed green building goals, strategies, and the most appropriate technologies. Our expertise led the team to examine the project’s potential to use only what nature provides onsite to operate the garden and expansion. Ultimately, this led to the team incorporating several passive energy strategies into the project. We emphasized strategies that subtly infused sustainability elements into the design to maintain a seamless integration of the new structures and surrounding gardens. In addition to reviewing the project vision, guiding principles, current status, and identified green goals, our sustainability workshop fostered teamwork and set a course for an integrated design process.

    Working closely with the team’s engineer, we developed a bioclimatic analysis of the project and identified opportunities to passively harness energy onsite. This analysis informed and influenced two energy-efficient and passive technologies: the installation of new geothermal wells, and the use of a concrete slab for thermal mass and radiant heating.

    The team installed 24 vertical geothermal wells beneath the Cultural Village Plaza to provide passive ground-source heating and cooling. Each geothermal well is 300-feet deep and 6 inches in diameter. A water-and-glycol solution is pumped through piping inside each well that either rejects or extracts heat, as needed, from the relatively consistent surrounding soil temperatures. Over the course of the year, this allows the Earth to act as a source for heating and cooling the buildings.

    A radiant floor system embedded within a concrete slab delivers heat and cooling to the Village House and Garden House. Within the slab, a continuous loop of piping draws heated or chilled water from the project’s water-to-water heat pump, which is fed from the new geothermal wells. The combination of the buildings’ concrete slab, well-insulated thermal envelopes, and deep exterior overhangs helps the buildings maintain a relatively constant interior temperature throughout the year, which allows the ground-source system to supply the majority of heating and cooling. In addition to saving energy, this innovative system helps address the project’s special visual and acoustic concerns.

    To complement the serenity of the gardens, the design incorporated a great deal of wood. Our experts provided significant value by assisting the contractor in sourcing environmentally-friendly, socially responsible and economically viable wood certified under the Forest Stewardship Council (FSC). FSC-certified White Oak and Alaskan Yellow Cedar comprise 60% of the project.

    Green Building Strategies

    Energy and Atmosphere

    • Improved building performance 39.5% better than the baseline building
    • 24 geothermal wells
    • Radiant flooring in a concrete slab
    • Heat recovery ventilation system providing 75% reduction in energy needed to condition incoming ventilation

    Materials and Resources

    • 60% of all wood is FSC-certified

    Indoor Environmental Quality

    • CO2 monitoring and demand-controlled ventilation Skylights provide daylight to regularly occupied office space

    Sustainable Sites

    • Parking lot stormwater captured and treated in a 27,000-gallon capacity detention pipe system, before being slowly released into the municipal stormwater system
    • Water catchment pools planted with native marshland plants treat rainwater
    • Vegetated roofs on two buildings improve stormwater management, conserve energy, and mitigate the urban heat island effect
  • The Outcome

    Distinguished as one of the most respected Japanese gardens of its kind in the world, the Portland Japanese Garden’s expansion beautifully integrates sustainable measures into Kengo Kuma’s acclaimed design. In keeping with the garden’s reverence for nature and spirit of peace, the new expansion deeply respects its immediate surroundings and greater environment. The innovative sustainability strategies will remain viable and durable to benefit future generations. Our efforts to ensure incorporation of sustainable wood products inspired the international designer, sparking far-reaching impacts. “Working with the garden has influenced my approach to future projects, especially integrating green and wood,” Kuma asserted.