Building science guru (and self-effacing Canadian) Dr. Joe Lstiburek takes a helpful sustainability-theory detour in the course of a lecture on building envelope fundamentals (Green Building Advisor podcast, available via iTunes):
Outboard of this [the thermal, vapor, air, and bulk-water barriers or ‘control layers’ of the building envelope] is the cladding system. And the cladding system serves three functions: number one, it provides aesthetics; number two, it protects the other control layers from exposure to ultraviolet light; and number three, it’s a physical protection, mechanical protection, against [projectile or other damage to] the other control layers.
Now, notice I said aesthetics. That’s a big deal. I’m fifty-three years old, I don’t know very much, but I know this: people don’t take care of ugly things. Think about that. People don’t take care of ugly things. If you want a building to last a very long time, if you want it to be truly sustainable, people are going to want to live in it, work in it, take care of it, and like it. Ugliness is not sustainable. That’s why we don’t let engineers design buildings. At the end of the day, the building has to be beautiful in order for people to take care of it — and therefore it will be truly sustainable.
Now, if it’s beautiful and people want to live and work in it and it’s going to be around for a very long time, we’ve created, in my partner’s words, ‘a machine that needs to be fed’ — needs to be fed resources. So the longer it’s around, the more resources it’s going to consume, and the way that we keep score is basically energy. Energy is about eighty percent of those resources. Now, that’s an arbitrary, pulled-out-of-the-butt value from me. My intuition and experience tells me that eighty percent of the resources associated with a long-lasting building is the energy consumption of that particular building. Much more significant than water. And much more significant than embodied energy.
So we’ve created a machine that needs energy. And the longer it’s around, the longer it’s going to consume that energy. So you’re going to want that building to be ultra-efficient. So you want a beautiful building that lasts a long time that’s ultra-efficient, because we don’t want it to consume many resources. And if we’re really good, maybe in several generations . . . that building might actually be generating energy. Or it might be made out of materials that are truly sustainable. . . . So don’t underestimate the aesthetics part of the cladding function, and then the sunscreen part, and the physical protection.