Amid some of the world’s finest scenery, seven home sites are available, tucked away in 200+ acres of nature preserve. The developers formed a nonprofit to try out a new model of landscape preservation: pay for preserving a large tract by selling just a few elite homesites while stringently restricting the right of buyers to build any sort of blot on the landscape.
We’re in New Zealand’s Southern Lakes district. If you’ve been watching Top of the Lake, we’re 40 miles east of Paradise, on the next big lake over, Lake Wanaka. If you’ve been watching The Hobbit … well, I’m not sure, but it’s a stone’s throw away.
The developers hired RTA Studios in Auckland to set an example, to design the model home for the first one of these sites. Small surprise that the result looks like a quasi-geologic formation that emerges, just barely, from the substrate. And claims the grandest set of carbon numbers I’ve ever seen. And won the Future House award from the World Architecture Festival and then, more recently, a Best of 2012—Sustainability award from Architizer.
Look at the pictures and think about the requirement, within this designated “outstanding natural landscape,” that buildings must have a “‘less than minor’ visual impact on the landscape from surrounding public open space.” Note the scarcity of trees to hide behind.
That alone is an impressive accomplishment. Note that no two roof sections have the same pitch and aspect—just like real topography.
As for the grand claims, C3 house is named for being Net-Zero Carbon in three categories. In the usual category—energy to operate the house—excellent insulation and well-planned solar gain minimize the demand, and solar panels elsewhere on the site zero it out. The other two are unusual. The architects claim that zero net carbon will be emitted in building the house (“embodied carbon”) and net zero will be emitted in taking it apart at the end of its life.
To support the claim of zero embodied carbon, they say that the carbon-spewing materials—steel, glass, and cement—are only 5% of the house, while relatively carbon-happy materials—local stone, local rammed earth, and wood—make up 65%.
The stone walls, or many of them, are held together by steel cages called gabion baskets, rather than by mortar. They say this helps a bit with embodied carbon (producing mortar spews carbon, but so does producing steel) but more at the end-of-life stage, when the cages can be cut and the walls easily disassembled. For the same reason, in many places the house components are placed or fastened together rather than glued together.
Looking at the C-shaped floor plan, see how it divides into a master sector, a kids sector, and a guest sector. The architects call this “zoning.” It saves heating energy because zones can be left unheated when not in use. Passive House people may point out that these energy savings are spurious because it is more efficient to heat a compact shape, i.e., one as close as possible to a cube. But cube houses (not the most graceful shape, no matter where you put them) would be out of the question on this landscape.
I love this house, I like its materials and its palette, and I love everything it stands for environmentally. As a science writer, I have to say that I think zero embodied carbon is practically impossible, but this house does an awesome job of minimizing its embodied carbon.
(To zero out the carbon emissions of their other materials, they must be assigning a high negative value to their wood—i.e., claiming that it sequesters a lot of carbon. I’ve noticed that that’s a popular point of view in New Zealand and scattered other places, but it’s a stretch. If you plant trees on unforested land, wait 50 years for them to grow up, cut some of them down to use in building your house, and replant, then your wood may have a negative C footprint. But not if you take your wood from an existing forest which is already sequestering that carbon.
A lot of the wood in this house is cross-laminated or other engineered wood; that’s a good idea for many reasons, but it also raises the embodied-carbon bar because it adds factory energy and transport energy.)