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July 23

Why does the Japan National Stadium have an asymmetric glassed patch?

What is the design rationale for the glass patch on the Japan National Stadium, making it look under construction or repair? Is that the only part of the roof that can be glazed to avoid sunlight on the pitch or seating? Thanks, cmɢʟee⎆τaʟκ 16:30, 23 July 2021 (UTC)[reply]

If I'm reading this article correctly, that's not glazing but open space: "The layers of eaves around the stadium were also inspired by the famous pagoda. The top and the third layer are provided with empty spaces, to allow in breezes and help control the temperature of the playing area and spectator stands. A thorough analysis of accumulated big data showing average annual wind conditions at the site made it possible to calculate exactly the angles and density of the “Kaze no Obisashi,” eaves to guide the wind, and to ensure air circulation without relying on air-conditioning equipment". Alansplodge (talk) 17:27, 23 July 2021 (UTC)[reply]

Rereading that last link, it seems to be referring to the gaps visible directly below the roof. Looking at the maps on this page, the glazing seems to be on the south of the stadium, perhaps to maximise natural light on the arena? The offset is perhaps due to the stadium being not exactly orientated north-south. I have failed to find anything that confirms my speculation. Alansplodge (talk) 23:08, 23 July 2021 (UTC)[reply]

A bit more Googling brings up Kaneka's see-through photovoltaic modules are adopted in the Japan National Stadium - they are transparent solar panels. Alansplodge (talk) 23:15, 23 July 2021 (UTC)[reply]

Thank you all for explaining. So it seems the glazing is to admit sunlight instead of shading from it. Wonder why it's just one small patch instead of the entire circumference (or perhaps half), then... cmɢʟee⎆τaʟκ 20:42, 24 July 2021 (UTC)[reply]

They are solar panels too and presumably very expensive, so I imagine that they put them where they would be most effective. Alansplodge (talk) 23:19, 24 July 2021 (UTC)[reply]

The roof is meant to provide shade to the spectators (and protect them from the rain, but a glass roof works for that too). In Tokyo, the sun always passes south of the zenith, so the southern section of the roof doesn't provide much shade to the spectators, but a lot of shade to the grass. Providing enough sunlight for survival to the grass in tall sports stadiums is challenging. Without this glass section, the southern part of the field wouldn't get any sunlight. Even with the glass section, much of the light is blocked by the support structure, but it might be enough, as Tokyo is at a fairly low latitude (35.7°, similar to Las Vegas, Tangier and Teheran). The transparent PV panels sound like a marketing gimmick. They could easily have put standard panels on the rest of the roof, but didn't. PiusImpavidus (talk) 10:10, 25 July 2021 (UTC)[reply]