The Energy Blog

SageGlass, Windows that can be Electronically Switched from Clear to Tinted, One of Top Ten Green Building Products for 2006

BuildingGreen, Inc., a publisher of green building news, has selected windows that can be electronically switched from clear to tinted, as one of the top ten energy efficiency products of 2006. Called SageGlass®, the product from Sage Electrochromics, Inc. uses "electrochromic" (EC) tungsten oxide coatings that turn dark when a voltage is applied to them, allowing automated or manual control of daylighting.

SageGlass® is an electronically tintable exterior glazing that provides glare control on demand while preserving views. Unlike earlier switchable glazing products that degraded with exposure to UV light, SageGlass is a multi-layer, thin-film tungsten-oxide coating that is as durable as low-emissivity coatings. The glazing uses 0.28 W/ft² to switch the glass from clear to tinted state, a process that takes several minutes, and 0.1 W/ft² to maintain that tinted state. Used with typical clear glass in an insulated glazing unit, SageGlass reduces the visible transmittance from 62% to 3.5% while reducing the solar heat gain coefficient from 0.48 to 0.09.

Hidden Thermal Solar Collectors for your House

Dawn Solar Systems Inc. produces renewable energy systems that integrate seamlessly with a building’s architecture, providing energy security and reducing operating costs by replacing fossil fuels and electricity with solar energy.  Residential and commercial systems are available today that can provide electricity along with hot air and water for heating and cooling, all harvested from a shared roof or wall surface.

That is the pitch that Dawn uses to describe their solar collectors hidden under the roof and/or walls of your house.  The system is installed during initial construction or a roof replacement.  Depending upon location and application design, an open or closed loop system can be created as fluids are pumped through the system and cycled through conventional heat transfer and distribution systems.  The following applications can be used with the heat collected in the system.

• Domestic hot water heaters
• Institutional, commercial and industrial process water systems
• Radiant floor heating systems
• Swimming pool heater
• Warm air heating systems
• Remote site or isolated cabin applications
• Integrations with photovoltaic systems
• Attic space cooling
• De-icing

Greenhouses Produce, Sell Excess Heat

Using GE’s new Lexan ZigZag sheet polycarbonate roofing material, Hydro Huisman and Corn. Bak BV are constructing greenhouses in the Netherlands that will produce more energy than they use. Lexan ZigZag sheet double-wall roofing panels provide higher light transmission than single glass, and insulation similar to multiwall glass or PC sheet. These energy-efficient properties will enable approximately two-thirds of the heat generated in the greenhouses to be sold as surplus.

ZigZag sheet roofing raises light transmission levels above those of single glass, especially during non-peak hours/seasons, while ensuring outstanding insulation to retain heat. The material is also lighter weight than glass, has excellent flame retardance and easy installation.  It offers a number of key properties. First, its angled design enables the capture of light reflected from the sides of the roof surface, thus increasing the total amount of light transmitted into the greenhouse to 90.9 percent – one to two percent higher than with single glass. Further, when the sun is low on the horizon – during winter months and at dawn and dusk – the material’s channels catch more light than flat glass. Second, the sheet offers insulation properties that are similar to those of double-wall glass; the material retains 45 percent more heat than single glass for substantial savings on energy demand: these savings can range from 20 percent to 40 percent.