When it comes to fluffy insulation, I’m a bit of an agnostic. I’ve used most types out there, except for denim. Installed properly, most insulations have their place. However, the question of embodied energy and the hidden carbon burden that so often accompany insulation nags me. The more I think about it, the more I think we should be using more cellulose insulation and less of everything else. Cellulose has the effect of sequestering carbon, meaning that it can actually reduce the amount of CO2 in the atmosphere. That said, it’s not a practical choice everywhere, particularly on the smaller jobs.
That line of thinking led me to YouTube yesterday morning because I got to wondering about how the manufacturing process worked for different kinds of fluffy insulation. That led me down several rabbit holes. I wanted to know how manufacturing affects their carbon burdens; and climate change and the potential end of life on the planet notwithstanding, the manufacturing processes are fascinating on their own.
The manufacture of both fiberglass and mineral wool are energy intensive. Both materials begin, essentially, as rock. Fiberglass starts as sand and soda ash. Blended and melted together, it becomes glass. The glass used in fiberglass has a high content of recycled material, around 50%. Most of that is industrial scrap, however. For example, about 20% of the recycled material Johns Manville uses is post-consumer. Still, industrial scrap or post-consumer waste, recycled content is hard to complain about.
Mineral wool is similar in that it, too is, wait for it, mineral-based. Mineral wool has an even higher recycled content than fiberglass, about 75% being post-industrial material such as blast furnace slag.
So, while that’s all well and good, cellulose beats both rock-based insulations in terms of recycled content. It’s about 85% recycled…