Page 30 - Climate Control News Magazine October 2018
P. 30

Making smart windows
economical
POOR DUCT CONNECTIONS AND LACK OF INSULATION CAN RESULT IN HIGH ENERGY CONSUMPTION, EVENTUALLY LEADING TO HIGH ELECTRICITY BILLS.
WITH AUSTRALIAN POWER prices increasing in recent years, everyone seems to be taking a greater interest in insulation and ducting.
Traditionally, the HVAC industry has been more concerned about faulty duct lining hinder- ing the flow of air moving through the building.
But more recently it has become everyone’s concern. Buildings leak as much as 30 per cent of their energy through inefficient windows. This is why research into this area of study is so important. For example, the US Department of Energy’s Argonne National Laboratory are working to commercialise a patented new pro- cess for synthesizing vanadium dioxide nano- particles which could make ‘smart windows’ economical. Argonne chemical engineer, Jie Li, received a US patent earlier this year to make it happen. Thermochromic smart windows work
automatically to pass infrared energy in winter to keep buildings warm and block infrared en- ergy in the summer to keep them cooler.
The nanoparticle-based vanadium dioxide films have approximately twice the solar modu- lation values for high and low temperatures as thin films, Li said.
Solar modulation is the amount of solar en- ergy that the vanadium dioxide material can control at low and high temperatures. Further, the material acts with switch-like rapidity, transitioning from blocking infrared to passing it through in micro or nanoseconds. Thermo- chromic technology has attracted industrial in- terest for decades but has been a niche product because of its high cost and limited perfor- mance, according to Ralph Muehleisen, the head of Argonne’s building science program. The problem has been that the best performing material for smart windows is vanadium diox- ide in nanoparticle form. Until now no one knew how to inexpensively produce the nano- particle form in enough volume to support commercialization. “The use of nanoparticles increases performance and the continuous flow process we’ve invented reduces the cost of man- ufacturing them, so this is finally a technology that makes sense for window manufacturers to consider,” Muehleisen said. “Perhaps more im- portantly, though, the manufacturing process itself has applicability to all kinds of other ma-
Smart windows work automatically to pass infrared energy in winter to keep buildings warm.
terials requiring nanoparticle fabrication.” Conventional thermochromic films incorpo- rate orderly vanadium dioxide material that re- sponds at a much higher temperature than those made with element-doped nanoparticles. The conventional windows must reach 154 de- grees Fahrenheit before they begin to block in- frared heat. Windows containing vanadium di- oxide nanoparticles that include tungsten achieve this critical transition temperature
at 77 degrees Fahrenheit.
“SYNTHESIZING VANADIUM DIOXIDE NANOPARTICLES COULD MAKE SMART WINDOWS ECONOMICAL.” - ARGONNE CHEMICAL ENGINEER, JIE LI.
Further, Muehleisen estimates that Ar- gonne’s continuous-flow processing technique could make manufacturing the nanoparticles at least five times less expensive than conven- tional methods. The smart window market was valued at $1 billion in 2014 and is expected to reach nearly $3 billion by 2021, according to Na- noMarkets. ✺
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