‘... Double glazing is slowly giving way to low-emission, high-performance single-glazed design. …the product can provide the same performance of double-glazed windows…’ says Kristen Brookfield, senior executive director of building, development and the environment of the Housing Industry Association (HIA) in a recent article in The Age (Saturday November 12th, 2016).

What’s next? That the earth is flat?

Anyone can check out the Viridian Performance Comparison Chart on the values of glass.

It seems that the interview was given without checking statistics, or is it really the belief of the HIA that single glazing is better than double glazing? If the latter is the case, the rest of the world would all be silly to invest into high performance windows which are at least double- and now often triple or even quadruple glazed.

Glass and glazing have a massive impact on the level of comfort in a building. Sitting near a single glazed window (or a window with a high U-value) in winter one can feel the cold coming in and in summer it’s the opposite. This is due to the radiant cold or heat coming in through the glass.

In a double or triple glazed unit it is not the glass itself that insulates but the space (airgap, argon gas filled) between. Yes, low-E coating on the correct surface can help reduce radiant temperature transfer; for instance, from 5.8 for a clear float glass down to 3.6 for a low-E coated single glass. The value for double glazing using clear float glass is already as low as 2.5 (so much better than a single low-E coated glass) and double glazing with low-E has the lowest value of 1.5. These are glass values only as window values vary depending on the frame material, style and airtightness.

Whichever way you look at it, the statement of the HIA senior executive director can only be seen as spreading false information. In today’s world though, architects, designers, builders and home owners are more knowledgeable and make their own decision after checking the facts. And the facts are clear, like glass.

(The article ‘Building a bright future by innovating’, page 3, The Melbourne New Homes Guide, The Age, Saturday, November 12, 2016, can be read here.)