Glass coatings are not new; the first low-e coatings, for example, entered the market in 1979. Each low-e spectrally selective coating can consist of 5 to 18 individual layers: silver layers, anti-reflective layers, protective layers, or others to facilitate production.
So, what’s new in glass coatings? Lots. There is so much innovation in the glass industry, but I’ll just describe one: electrochromics—also called smart windows or switchable glass.
How does it work?
Their construction has been described as “like a cell-phone’s lithium-ion battery except transparent and very thin”. Very thin colored electrodes are turned on when a voltage is applied to block light.
What are the most appropriate applications?
With such high-performing low-e coatings, what more could anyone want? In our dream world, on a warm spring day, the perfect west window opening would let breeze and light into the office in the morning, and, with the touch of a switch, block the hot afternoon sun. Electrochromic window coatings come close to that ideal.
What are the savings?
Counterbalancing the high initial cost are potentially smaller HVAC systems, avoided cooling, additional daylighting hours, and avoided curtain/blind purchases. These monetary benefits could be significant. Savings will be largest in east and west facing zones of commercial buildings, with some savings in south zones.
What are the non-energy benefits?
Non-monetary benefits could be even more important. Imagine the freedom to provide workers appealing views that can easily be “turned off” when glare or heat is unwanted.
What is the cost?
Costs for electrochromic windows are up to three times that of standard windows. However, if they follow trends of other emerging technologies, the prices can be expected to decrease 10-15% every year.
What is the status/availability of the technology?
This technology is readily available through multiple vendors.
What kinds of incentives/programs are available?
Right now, this technology would be evaluated under Custom Rebate programs. Incentives will vary depending on customer specifics, but in general, it takes a moderately sized commercial building to make a viable Custom Rebate project.
East and west facing glass should be avoided except where building site constraints make it unfeasible.