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How to Accurately Measure and Improve Glazing Performance

By November 24, 2021January 11th, 2022Energy Efficiency, Energy modeling, Solar Window Film
skyscraper with solar window film

In your efforts to improve building energy efficiency, you’ve likely already implemented LED light bulbs, solar panels, high-efficiency HVAC systems, and more. But have you considered glazing improvements such as solar window film as a viable way to improve building energy efficiency?

In today’s blog, we’ll be covering different types of window film, how to measure the performance of your glass and the benefits and credibility of window film products.

Solving the Heat Transfer Problem

Window construction poses several problems around heat gain and loss, causing wasted energy and higher HVAC bills. There are three methods of heat transfer from a glass window: radiation, conduction, and convention.

A few solutions are available to prevent your windows from excessive heat gain or loss, including window film, window coverings, gas-filled window panes, or Low-E windows. When looking for a preventative solution, it’s important to weigh cost, efficiency, and ROI.

What Is Solar Window Film?

Solar window film is a transparent, adhesive film applied to glass to reduce the Solar Heat Gain Coefficient (SHGC) from the sun’s radiation. Compared to other window solutions, solar window film is considered a flexible and cost-effective green glass alternative.

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The Construction of Window Film

There are at least three types of solar window film: metalized, IR absorbing, and multi-layer optically selective film. The number of layers used and the type of layers used in the construction of the window film impact its design, functionality, and performance. Let’s highlight the differences between the three film types:

  • Metalized film has a reflective appearance and is typically safe to use on dual-pane glass
  • IR absorbing film has a non-reflective appearance and is usually not suited for use on dual-pane glass
  • Multi-layer optically selective film is non-reflective and safe to use on dual-pane glass

Solar vs Dual-Function Security Film

What happens when you combine solar window film with security film? The result is a dual-function security film with energy-saving benefits, added building resilience, and protection from forced entry, civil unrest, harsh storms, and unnatural disasters. We call this combination “The Perfect Window.”

Properly Measuring Glazing Energy Efficiency

Today, there are several ways to measure the performance of your glass through its construction, strength, and appearance. In fact, using LBNL Optics® software, you can input and calculate the glazing energy performance of any glass type and window film combination.

To virtualize your project to the next level, you can input a building’s layout into an energy modeling software like eQuest to map out all your energy-saving factors. From there, you can configure things like orientation, shading, your HVAC system type, etc. This technology gives you a bigger and more accurate picture view of how all your efficiencies will affect your total energy performance payback.

Hardware Tools That Measure Your Glazing Performance

In addition to cutting edge software, there are several technology devices that are design to either identify your glazing type, and/or measure the energy performance of windows so you can benchmark performance baselines.


Measuring the structure of your window should be done with a high-quality meter, such as a Glass-Chek ELITE meter, which has the capability of scanning multiple coatings and glass panes.


The CRL Tempered Glass Detector Meter is a tool used to find out if your glass is actually tempered or heat-strengthened, reducing the risk of thermal stress fractures.

For more information about the technological advancements in glass metering, consider these videos:

For example, let’s compare the measurements of double-pane tinted glass and HP Surface 2 Summer Low-E glass.

Double-Pane Tinted

  • Tinted finish
  • Reduces the “existing” performance
  • U-Value score = 0.479
  • Improves SHGC
  • 513 → 0.245 (D=0.268)

HP Surface 2 Summer Low-E

  • Tinted finish
  • Has an accurate “existing” performance
  • U-Value score = 0.309
  • Improves SHGC
  • 247 → 0.139 (D=0.108)

What this illustrates is that a visual inspection may miss the mark when compared to measuring existing glass performance using these meters.  If a visual inspection concluded simply that the glass wasn’t clear (i.e. ‘tinted’) it might overstate savings if in fact the glass had a high performance (HP) summer Low E coating (which also ‘looks tinted’).

Why Choose Solar Window Film?

Now that we’ve covered the problems windows pose, explored what solar window film is and how to measure glazing energy efficiency, it’s time to answer the big question: Why is solar window film an efficient and effective energy-saving solution?

According to one of the most truste brands in the world, 3M™ window film can reduce up to 78% of the sun’s heat and shield up to 99% of harmful ultraviolet rays coming through your glass. But that’s not all. Some of the other benefits of using 3M window film include:

  • Lower energy bills
  • Eliminating hot spots from the sun
  • Reducing glare
  • Protecting your furnishings from sun damage
  • Evenly distributing natural light
  • Mess-free and quick installation
  • Utilizing existing windows/glass
  • Enhancing a single-pane window to perform comparably to double-pane windows
  • Providing a faster payback than window replacements

Make Your Building “Greener”: With Solar Control Window Film

Ready to dive deeper into the energy-saving benefits of window film for greener glass alternatives? Check out our webinar! We teamed up with NAESCO to present the Greener Glass webinar,  where our Director of Energy and Engineering Services, Mark Carlson, discuss every step of the glazing process from film types to measuring tools to testing methods and much more.


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