Glass Masonry Façade Conceals Green Urban Oasis

After so many centuries of living on a crowded archipelago with limited resources, the Japanese appear to have mastered the art of concealing small private spaces and preserving bits of nature within dense urban areas. Not long ago, we spotlighted the clever use of “rooftecture” to block out the bustling streets of Osaka, Japan, with a corrugated steel mesh curtain.

Now we turn to Hiroshima to focus on another screening material, clear glass blocks, which hide one of the prettiest, most tranquil open-air courtyards you’ll ever see — or, rather, not see, as the space is almost completely hidden from passers-by on the street. Once inside the “Optical Glass House,” designed by the firm Hiroshi Nakamura & NAP, visitors are rewarded with an open-air green space, with trees, filtered sunlight, a reflecting pool and a surprisingly quiet natural environment.

A private tree garden acts as a buffer between the living room (left) and the glass masonry wall (right) facing the street. Image by Koji Fujii / Nacasa & Partners, via Hiroshi Nakamura & NAP.

A private tree garden acts as a buffer between the living room (left) and the glass masonry wall (right) facing the street. Image by Koji Fujii / Nacasa & Partners, via Hiroshi Nakamura & NAP.

Located on a busy, noisy Hiroshima intersection, the three-story townhouse is viewed from street level as a flat two-story wall of glass bricks floating above a recessed foyer and wood-paneled garage doors. Through the 2-inch-thick borosilicate glass blocks, the vague outlines of trees and greenery can barely be seen.

The glass masonry facade, seen from the street, and a closeup of the glass-block structure (at right). Images by Koji Fujii / Nacasa & Partners, via Hiroshi Nakamura & NAP.

The glass masonry facade, seen from the street, and a closeup of the glass-block structure (at right). Images by Koji Fujii / Nacasa & Partners, via Hiroshi Nakamura & NAP.

Above the entrance, the ceiling opens up to reveal the transparent bottom of the reflecting pool, providing another glimpse of the courtyard through the shallow water. Once visitors ascend the stairs, they enter into the living room that connects directly to the spacious courtyard. Shielded from the street by the 93-square-foot glass masonry wall, the two-story courtyard shaft in nearly silent and dominated by Japanese maples and several other smaller trees.

View of second-story courtyard through transparent reflecting pool, as seen from the house's ground-floor entryway. Image by Koji Fujii / Nacasa & Partners, via Hiroshi Nakamura & NAP.

View of second-story courtyard through transparent reflecting pool, as seen from the house’s ground-floor entryway. Image by Koji Fujii / Nacasa & Partners, via Hiroshi Nakamura & NAP.

The buffered courtyard is open to the elements through a hole in the roof, providing natural ventilation for the whole house. The east-facing space is filled with morning sunlight that is filtered by the glass blocks and the tree leaves. During cold or inclement weather, the living room can be cordoned off by sheer curtains or enclosed entirely with retractable glass panels.

Because the 6,000 glass masonry bricks don’t have the strength to be a supporting or free-standing wall, the entire 13-ton mass is hung from the top rafter with 75 reinforcing rods that extend vertically through the glass blocks, along with embedded flat metal plates to provide lateral support.

Cross-section diagram of the Optical Glass House layout. Image via Hiroshi Nakamura & NAP.

Cross-section diagram of the Optical Glass House layout. Image via Hiroshi Nakamura & NAP.

In the rear of the 3,900-square-foot home, two other smaller courtyards contain an ivy-covered green wall as well as olive and Stewartia monadelpha trees. These rear chambers draw in more natural light to the kitchen, bathrooms, bedrooms and other parts of the building’s interior, where more optical glass walls provide views through the entire length of the house.

Randy Woods is a Seattle-based writer and editor with 20+ years of experience in the business publishing world. A former managing editor of Seattle Business, iSixSigma, Claims and Waste Age magazines, he has covered topics that include newspaper publishing, entrepreneurism, green businesses, insurance, environmental protection and garbage hauling (yes, really). He also contributes to the Career Center Blog for The Seattle Times and edits a photography magazine called PhotoMedia. When not working, he likes to hide out in Seattle movie theaters and attend film festivals—even on sunny days.