August 13, 2007 A rural family home built recently in Massachusetts has used, among other eco-friendly technologies and systems, insulating glass units that will significantly cut the amount of energy used in the home and ultimately result in cheaper and cleaner domestic energy. The Heat Mirror insulating glass unit from Southwall Technologies is a solar reflective film applied to a window’s interior that prevents the loss of radiant heat through the window at least three times more efficiently than double-pane glass.
“With an R value (the measure of thermal resistance used in heat transfer) of 7.7, the inside surface of the home’s Heat Mirror insulating glass remains close to room air temperature,” explained John Meade, Southwall’s Director of Business Development. “Heat Mirror is a better insulator compared to generic low emissivity, or Low-E glass (designed to allow for low solar gain while reducing the level of lost heat energy), which for comparison is also installed in the house.”
To put that into context, the R value of double pane glass window is R-2, while a double-pane glass window or skylight with a Low-E coating, is R-3, and closed-cell polyurethane spray foam has a value between R-5.5 to R-6.5. Heat Mirror comes in a variety of configurations and provides energy conservation performance ranging from R-6 to R-12, depending on requirements.
The Massachusetts house, home to a family of three, was built with a grant from the US Department of Energy (DOE) for less than US$200,000. Its “green” systems include a photovoltaics (solar cell) system expected to provide 74% of the home’s electricity needs, and a solar thermal system that should supply 44% of space and water heating. It also features 12” double walls, a tankless water heater, low-energy appliances, and fluorescent lighting, all designed to reduce carbon emissions, energy use and utility bills while providing a comfortable environment all year round.
“The installation of Heat Mirror in this DOE-funded project demonstrates the DOE’s commitment to advancing the use of glass products whose energy conservation performance far exceeds that of generic Low-E glass,” declared Meade, and ongoing monitoring of the home’s windows and other energy saving systems demonstrates this. Around 178 square feet of Heat Mirror is being utilized in the 1,300 square foot residence.
Southwall’s Heat Mirror insulating glass units are available for commercial and residential installation from over 50 window and insulating glass manufacturers.