Text on Flickr:
在1940年代至1970年代之間，當時冷氣尚未普及，香港一些學校採用遮光石屎板，既能遮光但又能通風，遮光石屎板大多設在建築物的西便，缺點是失去景觀和佔據空間，故商廈和住宅甚少採用。
The Vertical louver and horizontal sun break are applied in green buildings now. They are typically found in schools in Hong Kong from 1940s to 1970s.
No date given. My guess for the black/white photo are the 1960's.
