Thermally Broken Windows? You Don’t Need Them!

So you have been given the bad news by your energy rater, your new build needs thermally broken windows, you can expect that this will add 50% – 100% to the cost of your windows.

But is it true, do you really need thermally broken windows?

Generally energy raters assume that a particular level of performance in a window can only be achieved with thermally broken windows. So it is not that you must have thermally broken windows, it is that your windows must achieve a certain standard of performance.

It is performance that matters, not the window type

When we all enjoy lots of windows in our homes, and windows are a huge energy leak, then more and more we are needing to upgrade our windows to more energy efficient designs. It’s generally thermally broken windows that perform at a level better than non-broken windows of the same design, but the window still performs only as well as that window design permits and the test results that back that up (refer to http://www.WERS.net).

So, to decide whether you need thermally broken windows the only thing you need to know is what is the U value (Uw) required of the window, and this is on your energy report. SHGC (Solar Heat Gain Coefficient) is also a factor but is generally easily managed. Your energy report may even specify a window brand or manufacturer, but none of that matters, only the numbers are critical.

The only information you need to work this out is the Uw in your energy report.  While this may specify thermally broken, it is performance that really matters.