"I'm a building envelope engineer."
That's the answer I give when people ask what I do for a living. It often results in a blank stare.
So here's the follow-up: the mysterious world of building envelope science, engineering, and consulting explained in 2 minutes or less.
What's a building envelope?
The Building Envelope Design Guide and other industry sources offer a bunch of definitions of the building envelope (also known as the building enclosure). But let's keep it simple:
The "building" part of building envelope is a misnomer. I've applied building envelope design principles to other structures too - like the Weeks Footbridge across the Charles River between Boston and Cambridge, MA.
The Four Barriers
In building envelope science there are four barriers, or control layers, that make up the building envelope (Lstiburek, The Perfect Wall). If you keep those layers continuous and in the right places you're golden. That's all there is to it.*
These are the four "loads" that must be controlled by the four barriers:
- liquid water
- water vapor
The tricks come in understanding where those control layers go, identifying what materials perform what function, and figuring out how to keep them all continuous in the messy and hectic world of construction. "The devil is in the details" applies here.
Building Envelope Consulting
Building envelope consultants apply principles of structural engineering, physics, and materials science, as well as knowledge of architecture and construction to solve problems related to the building envelope.
Building Envelope Technical knowledge
There are many technical problems to solve related to the building envelope.
Problems from water leakage make up a huge percentage of construction litigation, so getting these technical details right can save a lot of headaches down the road.
Improving energy performance is huge: the building envelope is responsible for 25% of all building energy use, and buildings consume 40% of all U.S. energy.
To improve building performance in these, and other, areas we need to be experts at roofing, waterproofing, windows, and all types of wall assemblies. With this expertise we diagnose the sources of leaking roofs, design flashing details that will keep windows water- and airtight for many years to come, and decide where to put the insulation and how much of it to use... among many other tasks.
Building Envelope Education
At the root of any building envelope design or repair exercise there are common threads: communication and education.
There are often several solutions to building envelope problems - and the right solution may be different for different people. Cost and reliability are frequently at odds, and understanding the potential risks and benefits of competing options allows decision makers to act with confidence.
So, as a building envelope consultant, our most important task is often to be an educator.
Where to Learn More
If you made it this far, thanks for reading. Please let us know what you think in the comments below.
*Of course that’s not all there is to it.