Hi Folks, Anyone has experience with suspension film windows? An example below. These claim to have really high R-values approaching wall R-Values. I heard there have been problems reported with similar technologies. Any experiences to share? Are folks using these in the houses they are building? https://www.litezone.ca/superior-film-suspension.html

I reached out to the folks over at lite glass and asked them about reported prior concerns with this technology. Below was their response ### Yes, there have been failures in past suspended film IGU engineering. Not only in the film sagging or releasing but also seals breaking. Heat Mirror IGUs, for example, physically laminated their films in place between the spacers and offered no ability for the film to move when subject to heating and cooling cycles within the insulating glass unit. The film eventually weakened and failed (sagged, stretched or pulled away from the spacer assembly) Think of bending a piece of metal back and forth until it fails. The film would stretch and relax many thousands of cycles and eventually would not return to it’s original stretched shape. Visionwall IGUs had a spring mechanism design (film held in suspension using a tensioned springs) This made sense, mechanically speaking, but their downfall was they made their spacer assembly from metal. Metal has a different expansion co-efficient than glass so the frames were simply tearing themselves apart. Springs released causing film sagging, IGU seals broke and the unit integrity failed. Consider the following for our LiteZone insulating glass unit: The stress due to differential expansion of materials with changing temperature loads on our IGU has been eliminated. (Fiberglass and glass have almost exactly the same expansion co-efficient) The structural connection of glass to spacer is 3 times larger than what a typical IGU with a ½”spacer has. (Or two spacers for triple pane.) The connection of the glass lite to the fiberglass spacer is extremely strong but is also very flexible to accommodate any momentary stresses from 100+ mile per hour wind gusts. (ASTM tested and certified) The edge stress that conventional IGUs experience due to expanding air/argon with changing internal temperatures has been eliminated because LiteZone® is air filled and pressure equalized. Also, no escaping argon gas to reduce performance over time like triple pane units. The stainless steel foil that wraps the edge of LiteZone® is impermeable to water vapour. This we have proven by the water submersion test that you can see here. This foil is bonded across the face of the fiberglass spacer. Immediately under the foil is 5 mm of fiberglass, which has a low water vapour transmission rate. Even if somehow a tiny tear in the foil should occur, the exposed surface area of the fiberglass that water vapour could migrate through would be so small that the life of the unit would not be materially affected. ####

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Not to toot our own horn, but Alpen High Performance Products manfs windows with suspended film. They've mastered it over time. It's been used to reglaze the Empire State Building for instance (Alpen) and has a long, long history. It's in Antarctica too; literally all over the world. Many manfs gave up on suspended films over the years, or didn't simply understand how to build them correctly, but there are a very few left who figured out the quirks. Honestly, it's a wonderful product that yes, actually works and is reliable. These days, ThinGlass is replacing suspended film units, but suspended film still serves a wonderful purpose and does deliver exceptional thermal performance.

My 2 cents.

Not to toot our own horn, but Alpen High Performance Products manfs windows with suspended film.

Suspend‑film insulated glass units (IGUs) can indeed deliver impressive R‑values—almost matching those of wall assemblies—but they’ve faced reliability challenges in the past. Some early designs suffered from film sagging, seal failure, or spring‑mechanism breakdowns due to mismatched materials and thermal stress. However, manufacturers today who’ve perfected their design—especially those using fiberglass spacers matched to glass expansion—can offer durable, high‑performance units. While alternative technologies like ThinGlass are emerging, well‑engineered suspended film IGUs are still a solid option for boosting window insulation.

Triple-pane doors are usually worth it for better insulation, especially in an ICF home. Your linked door does have low U-Factor and SHGC, so one trick some people use is applying solar control window film to the glass — it can help reduce heat gain and improve comfort without changing the door itself. Otherwise, fiberglass or thermally broken aluminum doors from brands like Marvin or Therma-Tru are often recommended.