The Truth About the “Glass Demo”

Anyone installing replacement windows will naturally want the best product for the money, and in the case of windows, this often means the most energy-efficient product. Homeowners want to save money on their long-term energy costs, and low-E glass is one of the ways to do it. That is why the “glass demo” is such a common sales tool for replacement window companies, but it can also be somewhat misleading.

What Is Low-E Glass?

Low-E glass is glass that has been specially coated to block heat-carrying UV radiation. Four manufacturers in the United States make low-E coatings, and the products tend to be quite similar in performance and effectiveness.

What Is a Glass Demo?

In the glass demo, a salesperson will aim a heat lamp at several samples of glass, such as single-pane glass, insulated glass, the competitor’s low-E glass, and their low-E glass. The temperature will be measured on the opposite side, showing how effective each sample is at blocking heat transmission.

Why Is it Misleading?

Most low-E glass performs quite similarly, but the darker the glass is, the more heat and light it will block. During the glass demo, the salesman’s sample is often a darker glass, which will block more heat, but it would compromise the view if it were installed in an actual home. In the demo, however, it does make the product look more effective than competing products.

Low-E glass is designed primarily to block solar radiation from entering your home. This means that it keeps excess heat out in the summer, making your home easier and less costly to cool. In southern climates, this is ideal, as cooling is often more of a concern than heating. Installing low-E coatings on southern- and western-facing windows in these areas can significantly reduce cooling costs. The ability of a low-E coating to block the sun’s radiation is described by its solar heat gain coefficient or SHGC. This number represents the fraction of solar radiation that a coating lets into the home, on a scale from 0 to 1. For greater protection from the sun’s rays, choose a low-E coating with a lower SHGC or as close to zero as possible.

While low-E coatings are great for blocking summer sun, they do very little to stop heat from escaping your home in the winter. In fact, low-E coatings can make it harder to absorb heat from the sun in colder climates, a process called passive solar heating. To balance the performance of your home between the heating and cooling seasons, it is important to choose the right mix of low-E coatings and insulated glass for each area of your home. That way, you can block the summer sun as much as possible while taking advantage of passive solar heating during the winter in cooler climates.

How To Avoid a Glass Demo

At Zen Windows, we strive to offer our customers the best advice possible for their homes and the climate they live in. We feature no high-pressure sales tactics, and we will not make you endure lengthy and potentially misleading presentations about our low-E glass. That’s right — no in-home sales pitch and no pushy salespeople.

We offer a free, no-obligation quote online or over the phone, and we are here to answer any questions you may have about our replacement windows. With our quality products, simple financing options, and lifetime warranty, we make it easy to choose Zen Windows for all your replacement window needs.

Call us today or contact us online to learn which low-E coatings and products are best for your home. Request your free window replacement quote today!