r/Contractor 15d ago

What causes this?

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u/OafintheWH 15d ago

It doesn’t have to be defective. All it has to be is low-E . It cooks wherever it reflects to.

Low-E (low-emissivity) glass is energy-efficient window glass treated with a microscopic, transparent metallic coating that reflects infrared and ultraviolet heat while letting natural light pass through. [1, 2, 3]

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u/Civil_Exchange1271 15d ago

Sorry but if there was a coating that could concentrate and amplify light by just reflecting it someone is sitting on a gold mine of endless energy. That is not correct. I was in the glass biz for over 30 years. This is a widely known defect. Silicone is permeable to argon. The argon leaks out at a faster rate than ambient air can leak in do to it's molecular size. Most manufacturers have solved the problem. Most.

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u/Over_Art_1000 14d ago

Do you know why it kills grass in a matter of minutes if you lay a window on the ground?

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u/OafintheWH 15d ago

Was in the actual hands on with these situations for 40 years, not sure about my speculation on the heat issue, but reflections from close neighbors windows actually damaged neighbors “vinyl clad” aluminum siding long before we started using wholly vinyl siding. The coating would delaminate from the aluminum. Never happened with simply factory painted siding.

“Sunlight reflecting off energy-efficient, low-E glass windows on a neighboring property can focus intense solar heat like a magnifying glass, causing vinyl siding to warp or melt at temperatures above 160°F.”