Do you remember when few people understood what Net Zero meant? It wasn’t that long ago, but it’s certainly not the case anymore. Though there’s still some dispute about exactly how to define it, most people understand that a Net Zero building generates as much energy as it uses and a Net Positive building is one that generates more energy than it uses.
These metrics focus on the energy a building uses once it is built – known as operational energy – and have helped us decrease this energy use dramatically.
So now that we know how to make buildings that need much less operational energy, what’s next? How do we push the boundaries of sustainable building and save more energy?
How about considering the energy that goes into making the products that are used to build a building? This is known as embodied energy or embodied carbon, often referred to as the carbon footprint.
For an entertaining yet in-depth discussion of embodied carbon in construction and why it matters, I highly recommend “The New Carbon Architecture” by Bruce King and friends.
* Spoiler alert: buildings made of straw and wood have much lower embodied carbon and can even act as carbon sinks, making them Carbon Positive… or is that Carbon Negative…? I guess it will be a few years before we get these new terms sorted out!
Ever wondered why we don’t use conventional stucco on our buildings? Because modern Portland-based stucco is not vapor-permeable and it traps moisture. Natural plasters, such as clay and lime, are much more permeable.
Typical permeances of various plaster are:
6 mil poly vapor retarder .006” = <1 US perm
Cement-Sand stucco 1.5” = 1 US perm
Cement-Lime-Sand stucco 1.5” = 4-9 US perms
Lime-Sand plaster 2.0” = 9 US perms
Clay plaster 1.5” = 20 US perms!
For more, check out this article about the Stucco-Pocalypse!
You would hope that one of the materials responsible for the emission of huge amounts of carbon dioxide (Portland cement) would be included in a law about choosing materials with smaller carbon footprints. Nope.
Portland cement, the major binding agent in concrete, is one of the single largest emitters of greenhouse gases. But thanks to lobbying by industry groups, you won’t find concrete in California’s new carbon legislation, the Buy Clean California Act.
Read more here
On average in San Diego, it will cost about $500k for an existing house with land or about $200k for land plus $300k for a new house to be built on it: either way it’s a pretty steep climb for many of us.
Wondering why you can’t find an affordable home to buy in San Diego? This article explains many of the forces at play. There aren’t a lot of easy answers. I’m glad they touch on ADUs / Granny Flats as one part of the solution.