Reflective” Design: Mediating “Views” and “Environmental Impact Reduction

This tenant office building faces Midosuji Boulevard, the main thoroughfare in Osaka, Japan's second-largest city. Located within a uniquely dense urban environment, the design leverages the site's conditions facing Midosuji's beautiful ginkgo tree-lined avenue and the greenery of a nearby shrine. An exterior design was derived via simulation, using the presence/absence of views of greenery and sky as parameters for the optimal placement of exterior solar fins, in a novel approach to Japanese tower design. Terraces overlooking Midosuji were created on the lower floors, establishing the concept of a multi-layered plaza within a high-density city.

Positioned along the axis of a venerable shrine, the building's framework gains legitimacy through vertical pillars gleaming in a slate gray tone inspired by onbashira pillar forms, considered among the “roots” of Japanese architecture. This harmonizes old and new within the collective forms of the neighborhood, linking the shrine and the office building complex. The subtle, variegated tones of the solar control fins resonate with the ginkgo trees lining Midosuji, adding color to the cityscape.

A People-Centric Building on a Walkable Main Street

Based on the city of Osaka’s “Midosuji Future Vision,” walkable urban development through the conversion of entire roadways into sidewalks is progressing at Midosuji. Here, we pursued the ideal form of a people-centric office building within a high-density city. The high-value commercial first floor is designed as a large show window, with prominent storefronts that face the street. Above this, a large recess was created between the ground level and the 18 meter-high office volume, forming a lush outdoor terrace. This terrace serves as a viewing platform overlooking Midosuji Boulevard, where parades and festive events occur. It also creates a sense of expansive space and greenery for pedestrians looking up from the street, establishing a new “multi-layered plaza” concept that connects the city and the building.

From the first-floor entrance through the second-floor lobby to the outdoor terrace, native plants and water features draw Midosuji greenery continuously into the building. Users are welcomed into a biophilic environment. Upon entering the upper office spaces, the exterior fins, shimmering with delicate hues as they catch the light, add color. The evacuation staircase, typically relegated to the rear, was positioned adjacent to the elevator hall to actively incorporate natural light. Through the changing colors around the windows and dappled sunlight, this “Wellness Staircase” entices walking, contributing to user well-being.

“Reflective” Design

While environmental impact reduction and energy efficiency are now standard requirements for modern office buildings, we considered fulfilling the fundamental human desire for “views” to be crucial for office workers. We defined views of the sky and the greenery of Midosuji and the shrine as positive elements, quantifying their extent from within the office as “view potential.” We specified the required solar shading performance of the building in terms of total fin volume. Using computational design, we optimized the placement of these fins by comparing them against view potential. Detailed simulations assessed not only solar radiation load but also “total environmental load” which encompasses surrounding temperatures and internal heat generation, in order to maximize worker comfort.

Reflective design is a versatile and original methodology developed to mediate the conflicting objectives of views and environmental load reduction while reflecting the surrounding environment of the site.

Architectural Sustainability and Office Quality

This high-quality office space meets all user needs with a comprehensive BCP plan, including a 72-hour emergency generator and ample storage capacity. By adopting high-efficiency heat sources with sprinklers, latent/sensible heat separation air conditioning, outside air cooling, natural ventilation and CO2 control, energy savings of over 40% were achieved vs. baseline buildings of similar scale, earning Japan's highest environmental performance certification. The natural ventilation system automatically coordinates the opening and closing of ventilation units integrated into the curtain wall and shared-area ventilation windows. Meanwhile, an active control system allows users to adjust lighting and temperature settings. The building also employs a damping structure capable of withstanding seismic forces 1.5 times the maximum earthquake intensity resilience required by law. Upfront carbon reduction was also considered by utilizing the pre-existing building’s (undemolished) basement structure as retaining walls, and by actively incorporating recycled materials.

Project Details

Project name: Midosuji Daibiru Building
Purpose: Offices, Retail Stores
Location: Osaka City, Osaka Prefecture
Site area: 1,491.92 sqm
Total floor area: 20,275.57 sqm
Number of floors: 1 basement floor, 20 above-ground floors
Eave height/max height: 97.32 m
Main structure: Steel structure with partial use of reinforced concrete sections
Completion: January 2024

Client name: DAIBIRU CORPORATION
Lead architect: Nikken Sekkei Ltd
Main scope: Architectural design and supervision
Construction Contractor: Obayashi Corporation
Other cooperating company: SIRIUS LIGHTING OFFICE Inc [Lighting]; OK design Inc. [Signage（Wellness Stairwell)]

Photo credit 1: Akira Ito [aifoto]
Photo credit 2: Nikken Sekkei Ltd