Home Upfront Now Up Books Towns Structures People Firms Lexicon		Architrix - Munitoria: Early heat-reflecting glass _____________________________________________________ Author: Wegelin, Hans In: SA Architect Vol 24, Issue 6, Mar Date: 1998 Pages: 64 _____________________________________________________
Early heat-reflecting glass Pretoria Municipal Building 1968 The Pretoria Municipal Building (Munitoria) was recently in the news when the West Block was gutted by fire. This block is soon to be imploded, and whether it is to be rebuilt or not is still uncertain. But what is interesting about this building is that it was one of the earliest curtain wall buildings in South Africa, glazed with the then new heat-reflecting glass, locally known as Solarshield (the Santam building in Cape Town, designed by Chris Lochner, was the first). Architect Tony Doherty recalls a visit to the United States in the early sixties where the office of Kevin Roche and John Dinkeloo gave him information on the new laminated reflective glass. The Shatterprufe Safety Glass Company Limited, based in Port Elizabeth, had then taken licence from Kinney Vacuum in Holmdel in New York State for the manufacture of vacuum-coated glass, and the first vacuum-coater was installed in Port Elizabeth in 1964. The inner face of one sheet was coated before lamination to the second sheet. The silver coating for the Munitoria building was achieved through coating with aluminium, giving a shade factor of 0,36 and a visible light transmission of 60-70%. After a few years the silver coating disappeared through a chemical reaction with moisture inside the lamination, and all the glass was eventually replaced! Nowadays the silver coating is achieved in the polyvinyl butyral interlayer. It is also interesting to note that laminated glass has been manufactured in South Africa since 1929, with a celluloid interlayer, mainly for the automotive industry. Polyvinyl butyral has been used as interlayer since 1946, and laminated architectural glass has been manufactured in Port Elizabeth since 1960. This was before the days of float glass, so that the glass for lamination had to be specially selected for its true surface. Since the curtain wall faces north, south, east and west, air-conditioning engineer Henk Spoormaker accompanied Tony Doherty to the Yellott Solar Energy Laboratory in Phoenix, Arizona, to test the facade's heat penetration and reflective properties. The building is air-conditioned by central plant, piped and diffused through a boxed window cill. The role of safety glass during a fire is also noteworthy. Though in a small fire the glass will remain intact, in a large fire it might be better if the glass breaks or falls out of its frame, thus concentrating the fire and allowing water jets from fire hoses to penetrate the wall. The fire in Munitoria's west block did not spread out of control because of the glass curtain wall, but because of an unusually high fire load, no fire compartments, no sprinklers, and vertical spread through service ducts. Architect: Architect: BURG LODGE AND DOHERTY (Now known as BILD Architects)