I read a lot of stuff online about insulation and air barriers and other building science topics. I see a fair number of articles bashing certain products or materials. Sometimes it’s because the author sells a competing product. Sometimes they just don’t like a product. Take fiberglass insulation, for example. What thoughts just went through your head?
Those who have some building science training will look at the photo on the right and immediately see the symptom of a problem. The places where that formerly yellow fiberglass insulation has turned dark grey are places where air is moving through the fiberglass.
Some people will jump from that symptom straight to a guilty verdict for fiberglass. Sometimes they’ll even deridingly call it “filterglass” because it doesn’t stop the air from moving through it.
But is the type of insulation really the source of the problem here?
What about the next photo (Image #2, below)? It’s another case where the light-colored insulation has turned dark by picking up dirt from the air moving through it. Is the problem that they used an air-permeable insulation material?
Or could it be that there’s a huge hole in the ceiling? Seal the hole and the fiberglass will perform a lot better. When you think in terms of building enclosure control layers, it’s a lot easier to assign the blame correctly.
A good building will have control layers that control the flows of heat, air, and moisture. Just because a failure in the air control layer (air barrier) shows up in the heat control layer (insulation) doesn’t mean it’s the fault of the insulation.
Hey, I’ve bashed fiberglass in the Energy Vanguard Blog. I wasn’t condemning it as a product, though; the way it often gets installed is…