Translucent panels over windows cut energy use

Researchers at the Institute for Research in Construction at the National Research Council of Canada have been comparing the energy efficiency of windows covered with translucent panels compared to windows that are shaded with a perforated roller blind.
They found that the office with a translucent fibreglass sandwich panel over the window consumed 29% less energy for lighting than the office with the window and blind. The test was done combined with a daylight-linked lighting control system.
Average light levels in the room with the translucent panel were 2.6 times greater than those in the room with the blind. Light exposure in the 450-470 nanometre range of the spectrum, which is thought to include the key wavelengths for heealth benefits, was approximately eight times greater in the room with the translucent panels.
Being able to control direct sunlight is an important aspect of successful daylighting and translucent panels offer a potential sollution, although on the downside the panels obstruct the view to outside.
See Construction Innovation, September 2005, http://irc.nrc-cnrc.gc.ca/pubs