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A thin coating of gold is often used in building glazing to reflect heat radiation, and helps keep buildings warmer in winter and cooler in summer.
Gold Window Coatings
Normal window glass is nearly transparent to solar radiation (ranging from ultraviolet to infrared wavelengths). Therefore, huge glazing areas of many buildings may result in increased loading on air conditioning facilities and overheating of interior rooms and offices. In order to reduce this effect, thin gold coatings are occasionally used on the glass during the glazing design. This is because vacuum-deposited gold films have superior infrared shielding capacity.
When making these materials, it is essential to make sure that the amount of visible light transmitted by the glass is acceptable, and this can be regulated by the thickness of the gold film and the glass itself. During winter, double glazing with gold coatings is also useful in reducing heat loss outside of buildings.
Gold in Architectural Glazing
The Royal Bank Plaza building in Toronto is one example where gold has been used in architectural glazing. The building includes 14,000 windows that are all coated with pure gold (70,000 g in total).
The gold lowers heating and ventilation within the building, thereby making it cost-effective. Eureka Tower is the second tallest residential building in the world. The top eight floors of the building have 24-carat gold-plated glass windows, and the building was officially opened in October 2006.
Manufacturing Gold Architectural Glazing
For more information on the science and technology of this application, the paper can be downloaded from the archives of the journal Gold Bulletin.
Manufacturing gold-coated glass is a very costly process (due to the use of vacuum technology rather than the cost of this precious metal). Therefore, research is ongoing to develop advanced methods to produce these materials. This may involve the use of gold nanoparticulate coatings to precisely tune the glazing’s reflective capacity. An additional benefit of this evolving technology is that a more attractive range of glazing colors can be achieved.