Cork has always been one of our favorite materials. It is a completely renewable resource, sustainably harvested every 8 or 9 years. Cork forests in Portugal have been under threat because of declining demand for cork, as more vintners turn to twist tops and plastic corks for their bottles, so finding other uses for it actually is a good thing.
The cork forests of Europe are also habitat for the cutest thing you ever saw, the Iberian Lynx; lose the forest and lose the lynx. Now if that doesn't make you want to use the stuff, I don't know what will. Thermacork, the supplier of architectural cork, notes other benefits:
Cork forests are considered biodiversity hotspots, providing food, shelter, and feeding groups for a number of species. One of the most beneficial aspects of cork forests are their ability to reverse environmental damage. They protect soil from desertification by protecting against wind erosion and also serve as a natural fire barrier, reducing the risk of forest fires. A major benefit of cork forests is their ability to act as "carbon sinks", capturing greenhouse gases and CO2 in the atmosphere. In fact, cork forests in Portugal trap 4.8 million tons of CO2 emissions a year, roughly 5% of the country's emissions.
Cork is also fire resistant, a great insulator and and hydrophobic, which is why it makes such good stoppers for bottles. Green building expert Alex Wilson used it in his own house as the exterior insulation, but he put cladding over it. Cork also looks great, which makes it a very interesting choice for cladding a building. This is common in Europe, but this may be the first time it has been done in North America.
Chad Ludeman and PostGreen Homes are using it in their latest project in Fishtown, a rapidly gentrifying part of Philadelphia where Postgreen has had a big impact. (see my earlier tour with Chad here) What I love about PostGreen is their humor, and their understanding about what green building is: urban, gritty, straightforward and without a lot of green gizmos, or what Postgreen partner Nic Darling calls, Polishing a turd.
OK, so it's a bit harsh. Turd is, maybe, an unnecessarily rude word to use to describe what are often pretty nice homes, but the concept is sound. Most of the builders and developers reporting high premiums for pursuing LEED are still trying to build the exact same home they have always built. They are simply adding features to make that same house energy efficient, healthy and sustainable. This gets expensive.
They are working with Orange Concept, a small young firm "on a mission to prove that modern design does not have to be cold, minimalist and crazy." Like many of Postgreen's other projects, the design is simple and spare, much like the older buildings in the area. They look almost too simple until you see them in context.
Cork isn't cheap; it costs about three times as much as expanded polystyrene. However using it like this, the builder doesn't have to pay for exterior cladding; the insulation is the cladding. That goes a long way to covering the cost. Facade cork comes in panels one meter by half a meter (39" x 19-5/8") up to six inches thick. Insulating value is about R-3.6 per inch. BuildingGreen calls it the greenest insulation material and I agree.
Cork is also used inside the house as an architectural detail; this is also a great idea. It has a warm appearance and is a killer at soaking up noise. Once again, great work coming out of Postgreen. I just cry when I see the price of $399,000 for a new three storey house built like that; where I live, this is what you get for twice that. Time to move to Philadelphia! Get yours here.