via the sietch
Over at the Sietch Blog, an environmental site that I respect a lot, a roofer named Leo defends PVC roofing as one of the greenest roofs. He isn't wrong; it comes in white, and white roofs are all the rage, it lasts a long time and is a lot less problematic than asphalt or bitumen roofs. And while they are made of vinyl and full of evil phthalates, we don't usually have babies licking our roofs.
He is also even-handed, and links to Greenpeace and discusses their concerns about dioxins and phthalates. But the devil is in the details, or in this case, the language. Let's look at just one paragraph.
The paragraph we will parse is this: (emphasis mine)
Chemistry of PVC: Vinyl is essentially derived from two simple ingredients: fossil fuel and salt. Petroleum or natural gas is processed to make ethylene, and salt is subjected to electrolysis to separate out the natural element chlorine. Ethylene and chlorine are combined to produce ethylene dichloride (EDC), which is further processed into a gas called vinyl chloride monomer (VCM). In the next step, known as polymerization, the VCM molecule forms chains, converting the gas into a fine, white powder – vinyl resin – which becomes the basis for the final process, compounding. In compounding, vinyl resin may be blended with additives such as plasticizers for flexibility, stabilizers for durability and pigments for color. Through various plastics processing operations, manufacturers are able to offer versatile products with customized performance characteristics.
Salt. It sounds so innocuous. Except electrolysis of it to make chlorine is hugely energy intensive, almost as much as making aluminum. Most of that energy comes from fossil fuels. So chlorine may be a "natural element", tossed in because of course, a natural element is a good thing, like Radon, but its production is anything but. It also is a significant greenhouse gas.
A big byproduct of the manufacture is lye, or sodium hydroxide, another caustic toxic.
Then you mix this product of burning fossil fuels with- more fossil fuels, used to make ethylene. Put that together with chlorine and you almost have vinyl, which "may be blended with additives such as plasticizers for flexibility, stabilizers for durability and pigments for color."- our advisor tells us that:
Vinyl only exists with additives up around 50%. (+/- 10) Without stabilizers (lead or calcium or tin based) it would quickly break down. These too are pretty energy and material intensive. Vinyl siding is about 30% to 40% titanium dioxide as I recall to handle the solar input. There's another energy and resource intensive input. Roofing likely has it as an ingredient too.
There are other parts of the article that I could argue with as well, but that paragraph is enough. Vinyl roofs are a huge advance in roofing; they are effective and reflective. The Guardian recently reported that a mass movement to make roofs white could delay climate change by ten years.
So why greenwash vinyl? Why pretend that it is "natural"? Why not just say that there is not much out there right now that does the job better, and that on balance it is a better choice than the alternatives. It probably is.
More on PVC and Vinyl in TreeHugger
Quote of the Day: Michael Schade on PVC and Environmental Justice
TreeHuggerTV: Sam Suds and the Case of PVC