Sparklike is the developer of the world’s first non-invasive gas analyser for insulating glass units. The Sparklike Handheld™ and Sparklike Laser™ devices have become the de facto world standard for gas fill measurement of IGUs. Sparklike products are used daily by leading insulated glass manufacturers, testing laboratories and window processors worldwide.
Gas-filled insulating glass units (IGUs) achieve their thermal performance primarily through reduced heat transfer in the cavity. The advantage of gas fill lies in the significantly lower thermal conductivity of noble gases compared to air. While air has a thermal conductivity of approximately 0.024 W/mK, argon measures about 0.016 W/mK and krypton 0.0088 W/mK. This difference directly contributes to lower U-values and improved window energy performance.
Argon is the most commonly used insulating gas due to its balance between thermal performance and cost. Although krypton can further reduce heat transfer, its material cost is typically 200 to 300 times higher, limiting its use to specific high-performance applications. As a result, the thermal performance of most commercial IGUs depends largely on achieving and maintaining a sufficiently high argon concentration.
From a performance perspective, gas concentration is critical. IGUs are generally designed to reach their declared U-values when gas content exceeds 90 percent.
Studies and simulation data show that when argon concentration drops significantly below this level, the thermal performance deteriorates measurably. For example, reducing argon content from above 90 percent to around 70 percent can result in a noticeable increase in heat transfer, diminishing the insulation benefit that justified gas filling in the first place. In practical terms, this means the IGU no longer performs as designed, even though it may still appear visually unchanged.
Over the service life of an IGU, gas loss caused by pressure differences between the cavity and ambient conditions is typically accepted at up to 1 percent per year. Higher leakage rates are commonly linked to deficiencies in sealing or processing quality and can accelerate thermal performance degradation.
The development of non-invasive gas measurement methods has enabled direct verification of gas concentration without damaging the IGU, allowing manufacturers to better correlate measured gas fill levels with thermal performance outcomes.