Architecture studio Hiroshi Nakamura & NAP has designed the “Optical Glass House” in Hiroshima, Japan, that aims to acoustically protect residents from the main road outside, whilst providing light and views for the residents within. The delicate glass blocks belie the structure and a complex casting process is employed to create the 13 ton (11.7 tonne) facade that shows-off the buildings tree-filled courtyard and looks like a shimmering waterfall to the outside world.
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Located amongst the tall buildings of downtown Hiroshima, the first floor garden and glass facade are positioned on the street side of the structure to maximize sunlight from the east and provide a visual link to the city. Light filters through the 6,000 glass blocks that are cast to produce high transparency using borosilicate, the raw material for optical glass. The casting process involved slow cooling of the 50 x 235 x 50 mm (1.96 x 9.25 x 1.96 in) blocks to remove the residual stress necessary for their combined function in the facade.
At a size of 8.6 sq mt (92.5 sq ft) the glass wall is supported by 75 stainless steel rods suspended from a reinforced concrete and steel frame, that puncture through holes in the glass blocks. Lateral stress is also reduced by embedding a 40 x 4 mm (1.57 x 0.16 in) steel flat bar within the glass blocks at 10 cm intervals. This reinforcement stipulated a 6 mm (0.24 in) sealing joint between blocks that enables the transparent effect to be achieved.
The concentration of filtered light is also realized through the water basin skylight of the entrance hall, whilst the open living room located on the far side of the oasis courtyard is only protected from the elements with a sputter-coated lightweight metal curtain. All in all, the light-filled small scale of this single home is a delicate contrast to the high-tech wide avenues that have characterized the reconstruction of Hiroshima.
Hiroshi Nakamura worked under the famous Japanese architect Kengo Kuma before setting up his own studio in 2002, and in 2012 the Optical House earned his studio an ar+d award for emerging architecture.
