There's a new breed of glass that outperforms just about every window on the market. A double-pane window of this new "super glass" loses up to 42 percent less heat than a standard double-pane window. It's even better than a triple-pane window because it weighs less, costs the same and can save as much or more energy. This year, most major manufacturers have promoted the super glass in storm windows, as well as patio doors and skylights. It's sold under a zillion different brand names, but it's known generically as low-emissivity glass.
A low-emissivity window or patio door looks like an ordinary window or patio door with double
pane glass in it, but there is one key difference: the inside face of the outer pane has a metallic coating that's a mere few hundred atoms thick. This microscopically-thin coating can barely be seen but it stops radiant heat loss by not emitting it to the colt outdoors. Hence the higher R-value of low-emissivity windows.
Not only will your heating bills notice this improvement but you should, too. In winter, your
thermostat may be set at a warm 70ºF, yet you'll feel chilled sitting near an ordinary window. Some of that chill may be due to air leaking through its cracks, but some is also due to the radiant heat loss of your warm body to that cold glass. If your windows are skinny single-panes, the room-side surface of that glass is only 14ºF when it's 0ºF outside! If you have ordinary double-pane glass, the room-side glass temperature will be about 41ºF, but with low-emissivity glass, the room side surface will be 51ºF.
For all its benefits, super glass doesn't cost much more than standard windows. Another type of super glass is known as Heat Mirror. It's based on the same principle of reducing radiant heat loss, but in this case the metallic coating is deposited on a clear plastic film, which is then
suspended between two panes of glass. You get a window with two benefits: (1) the insulating value of a triple-pane window and (2) the low-emissivity coating for an R-value of about 4.2.
Heat Mirror was developed at the Massachusetts Institute of Technology in the 1970s, partly with
federal funds, and has been in production since 1981. It is sold to various window makers, who
incorporate it in their lines. Three widely-distributed carriers of Heat Mirror are Certainteed, Hurd, and Louisiana-Pacific windows. When shopping for super glass, look for the longest warranty and the lowest U-value. Window literature generally rates energy performance in terms of U-value. The U-values of super glass vary, depending on the glass manufacturer and the type of coating. The coating can be applied to glass in two ways: by a "pyrolitic" method, while the glass is still molten, and by a "vacuum" method, once the glass is hard. The vacuum method results in a better U-value, but creates handling problems for window manufacturers, and cannot be placed in storm windows.
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On Selling Real Estate
Just my thoughts: Dennis Robitaille
As a licensed home inspector, it's none of my business to evaluate how good or how bad a real estate agent does his or her job. I do, however, feel the need to comment on a practice which I feel makes it more difficult to sell real estate.On more than one occasion I've received calls from prospective home buyers, who've been told by a real estate agent, "no matter what the home inspection uncovers, the owner will not repair anything or reduce the sales price." This type of restriction puts pressure on the buyer, and increases the chance of the buyer walking from the deal if a major problem or several small problems are uncovered.A lot of real estate agents prep prospective home buyers by telling them a home inspection is only to learn about the property and is not to be used for re-negotiating. In today's market, this approach towards home inspections will result in mis-trust and broken deals. Yes, many of the defects / deficiencies uncovered during a home inspection are so called normal maintenance or age related items. Some however, are major defect or cost items or safety hazards which a prospective home buyer may not be able to afford or is not willing to deal with. My suggestions for real estate agents; 1. Educate your clients (the home sellers) to the fact there could be unknown major defects or deficiencies or safety hazards uncovered during an inspection. 2. Don't put restrictions on how a prospective buyer might want to use their inspection report. Things might go a bit easier for all those involved in the sale if these suggestions are followed.
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