The
USGBC has been saying for years that green building do not have to be more costly on a first cost basis than other buildings.
To me, this has never made sense. Nor am I alone in my lack of faith. Many I know aren't convinced.
As a mechanical engineer, specifying building HVAC systems, it's always seemed crazy. I’m supposed to provide a super-efficient HVAC system, with great filtration, better controls, and high outside air. That's supposed to be less first cost than a bare minimum HVAC system? Yea, right.
So, where does this first cost claim come from? How is it supposed to work?
To understand, we have to recall a little piece of economic theory that we probably have hidden in the back of our minds somewhere, subconsciously feeding us questionable information.
Remember the theory of diminishing marginal return? It goes like this: Say I have a factory with a giant machine and a bunch of workers that produces 100 units per day at a production cost of $100 ($1/unit). If I want to increase production to 110 units per day, my costs to speed up the machine, pay more workers, and so on, go up to $115 ($1.05/unit). If I want to increase production further to 120 units, my costs go up to $150 ($1.25/unit). For each marginal increase in production, the cost per unit increases, and the return on investment decreaes. In economics textbooks, this is shown as a curve, with units on the horizontal axis and costs on the vertical axis. The curve gets steeper as it goes up, each increase in units representing more cost than the one before.
Most of us accept this economic principal without too much question. Standard cars on the local retail lot can drive 120 miles per hour, but if you want a car that can do 150 miles per hour, it costs a lot more. And if you want a car that can do 180 mph, it costs vastly more. Most of us accept that better costs more. And, in the higher quality products, slight improvements can cost a whole lot more.
Unfortunately, we accept this too easily. The principal of diminishing return is valid
only for two variables in a fixed system. Introduction of a
third variable, or any
change in the system, destroys the curve.
Going back to the factory example: Diminishing marginal return applies to costs and outputs in the
same machine. If I change out the machine, the whole relationship is shifted. For example, someone could offer me a new machine, of an entirely different design, that produces 1000 units per day, uses less energy than the old one, costs less than the annual maintenance on the old machine, and enables me to get rid of 50% of my workers. With the new system, the diminishing return curve is completely shifted.
Now, let’s talk about green buildings.
The idea of producing green buildings at equivalent or lower cost is based on finding a way to
revolutionize the system, drastically shifting the marginal return curve from that of a normal building. It means that we have to look for some thing or a combination of things that can be done better, which also create opportunities for first cost savings.
The good news is, we don't have to do the research and investigation ourselves. The shift-providing synergy and opportunity has already been identified:
eliminate the air conditioning.It sounds crazy to me. But, with my 10 years in the air conditioning industry, how can I be anything less than offended?
But, let's walk through the concept: Assume we design a building with super insulation, super-insulating glass, 100% daylit spaces, and enough thermal mass to weather the seasons without needing cooling or heating. At that point, couldn't we just ventilate the building with some clean fresh air through a heat recovery unit and be done?
"No."
At least, that's my knee jerk reaction.
Ok. But, let's keep going with the idea: If we were able to eliminate the heating and cooling system and provide only a ventilation system, that would cut a significant chunk out of the building construction costs. Ideally, that saved chunk would be enough to pay for the super insulation, super glass, daylighting, controls, and whatever else was needed to make the building green while still providing an overall cost savings to the project.
What do you think?
To my fellow mechanical engineers, are we ready to start designing ourselves out of our projects? (And, if we are, upon what can we base our fees for doing so?)
I didn’t make this whole concept up, by the way. It’s not my argument. I read it Hawken’s book
Natural Capitalism. It’s also a prominent theme in the USGBC’s literature. There is a lot of talk about natural ventilation, displacement ventilation, and the like. I’m not sure, based on their case studies, how often it is being done, but the idea is one of the building blocks of the cost-effective green building movement. This is, of course, the idea advocated by
Christine Ervin (former Clinton Secretary of Energy and CEO of USGBC) and her crew. Their idea seems to be that if green design and good environmental practice can be cost effective then government won’t have to regulate it.
What was most eye-opening to me was that, in reading this argument, it became clear to me that attempting to do cost effective green buildings without radically shifting the system is futile. Neither is it correct to assert that all green buildings are cost effective just because USGBC says they can be.
If a green building has all the same parts as a normal building, and every one of them is better, more efficient, and more expensive, the building is going to cost more. That’s pretty simple. Don’t get me wrong. I fully believe it is possible to build a green building out of the same parts as any other building, air conditioning and all. But, to be cost competitive to a traditional building, something has to give, and that’s the tricky part.
