How many building energy modelers are there?

This is a question I always wonder about when I need to estimate the size of the BEM market (US, international, or otherwise). Someone must have figured out some good numbers by now. And yet I don't think I have seen any estimate published in the usual papers that discuss the BEM industry...at least the ones that I have found.

It seems like the question could be answered in two different ways:

How many people have "energy modeler" as their job title?, or
How many people use energy modeling in the course of their job?

I would be happy with either number.

Here are two data points. First, the last four updates of EnergyPlus (7.2, 8.0, 8.1, and 8.2) have each been downloaded about 20,000 times. 20,000 seems high for EnergyPlus users, but lets use it for lack of a better estimate. Second, last year's round of AIA 2030 reporting showed that about 16% of projects that were modeled, were modeled using EnergyPlus (FWIW, most projects were modeled using either TRACE or DOE-2.2). Let's extrapolate from projects to users to mean that one of every six modelers uses EnergyPlus. That's probably a fair estimate at this point. Combining these, we get that there are 120,000 energy modelers in the world.

That seems insanely high—for comparison, there are 83,000 registered architects in the US and anecdotally the ratio of architects to modelers is at least 20 to 1—but it's one bottom-up estimate. It would be interesting to see estimates using other data sources.