Landmarks Not Landfill: Prism Glass

I am at the 2008 Heritage Conservation conference in Collingwood, Ontario, where the theme is Landmarks Not Landfill: Heritage Preservation and Environmental Sustainability.

Romas Bubelis, architect for the Ontario Heritage Trust, did a presentation on how design and construction techniques from the 19th and early 20th century were naturally green, given that they didn't have much affordable artificial lighting or ventilation and had to develop zero-energy techiques. I almost fell out of my seat in the Gayety Theatre when he described prism glass, which I had seen on buildings for years but never understood the point.

Prism Glass was originally developed to channel light into the holds of coal-carrying ships, so that one could see in the holds without needing a candle or lantern, a wise move in such a space. Stanford White used it with great success in the floor of Penn Station, where light from the dramatic skylights above filtered through to the train tracks below the floor of the station. (last week's visit to the current Penn Station followed by a viewing of this picture brought home what an architectural crime the loss of this building was)

The 19th century version of Architectural Graphics Standards would say with an 11 foot ceiling, light would penetrate 24 feet. But In 1897 the Luxfer Company introduced the Luxfer Prism glass, made at a wide range of different angles for different latitudes and purposes, that would bring natural light deep into stores and offices. Now buildings could be deeper, stores could be brighter, and buildings sprouted bands of translucent panels of small panes above their picture windows. And I thought it was just to cut down glare.

Of course, when electric lighting became affordable it was much more consistent and controllable and Luxfer prisms were no longer considered au courant. Yet the idea has returned in solar tubes and fibre optic systems and other expensive systems that are far more sophisticated than a fresnel lens mounted in a transom window.

I have a lot to learn this weekend. Read more on Prism Glass