A New Way of Thinking for the AEC Community: Upfront CFD Simulation

There is a good chance that where you are sitting right now there is some sort of environment control system-- fancy word for HVAC or simply a heating and cooling system. It is an ever expanding business. Architects and engineers are constantly being pushed to optimize the air flow distribution and temperature values. It can be a fairly sophisticated engineering problem involving humidity, comfort temps, solar radiation among other things. It's not getting any easier as there is more and more pressure to be green and maximize efficiency. It's not only being required from a budgetary perspective, new regulations are now requiring it. In the past, often the fix was to simply over size the unit, manually alter the ducts, and even more and more rigging to solve the problem.

One would think that a problem that involves air flow, ducts, dampers, diffusers, grills, filters, blowers, solar loading, ever increasing heat generating electronics- that computational fluid dynamics (CFD) would be a no brainer? Well, it's not really the case. In fact, up until recently it was used sporadically at best. Some outfits used it all the time, others rarely used it at all. But as with everything- times are changing. Now AEC firms are being required to provide simulation proof that the design will work and that the energy consumption meets certain requirements. This is sending folks scrambling to outsource the work, which is fairly costly. Others are investigating specific vertical very HVAC simulation tools. The problem is neither of these solutions really fits into their current process. Check out the variety of problems we are solving.


Historically, folks in this industry have used AutoCAD or Microstation. Their entire world has been born to think in 2D and expand into 3D. But with tools like Autodesk Revit making traction in this world, 3D is clearly a step in the right direction. There is really no benefit to going to a 3D MCAD CAD system, like Autodesk Inventor. But Revit now opens up an entire new world for this community. It is the launching point to really embracing CFD. Check out the videos below by CFdesign guru, Parker Wright. Parker has been fortunate to be right in the thick of things in this world. Working in the heart of NYC, he is hearing the evidence first hand right from the firms themselves. Check out his approach to solving the problem.

The below video shows the basic modeling inside Revit.

Here is setting up the CFD model leveraging the Revit geometry inside CFdesign.

Finally, reviewing the flow and thermal results in CFdesign.

I think we will be seeing more and more usage in this world. We are literally at the calm before the storm. The problems are only going to get bigger and happen more often. The good news is the technology and integration to solve the problem is growing even faster.

An Underground Subway Stop is a Great Platform for Upfront CFD

HVAC applications keep popping up more and more. Anything from new construction of "green" buildings to retrofitting 100 year old subway systems.

Here is a model I worked on recently that allowed us to optimize the airflow inside an existing subway station. We were able to try a variety of what-if scenarios -- with and without cars, with and without people as well as various heat loads (best and worse case scenario).

HVAC designers should be using Upfront CFD everyday!?!

Seems logical, right? What other industry deals primarily in air flow and thermal management? A typical HVAC designer/engineer spends his time sizing duct work, fans/blowers and attempting to evenly cool or heat large areas. Seems like a no brainer that they would be using Upront CFD. They certainly have the need. But, in fact, it is not commonly used in this industry.

There are many guys/gals in this industry that have a tremendous amount of experience and designs are based on rules of thumb etc. I did a bit of this back in the day in the nuclear world and was priviledged to use a "ductometer". So, in general, it has worked up to this point. Unfortunately, it has worked at a cost. Units are often under and over sized, which results in high utility costs. Not to mention the impact on the environment. Flow straighteners are used in a pinch. The cost of retro-fitting existing designs can be tremendous. So, why isn't Upfront CFD being used?

I think there are many reasons. Primarily, I think that the traditional CFD tools are too expensive, too complicated and are quite frankly, just overkill. The Upfront CFD market has been primarily targeted to folks that are driving MCAD (Pro/e, SW, Inventor etc) tools. HVAC guys are designing in 3D, but are probably using AutoCAD and MicroStation. They actually have access to 3D CAD files via an SAT output from AutoCAD, but it can be clunky.

Times are changing. Many architectural firms running AutoCAD are being exposed to Inventor. Believe it or not, Rhino is popular in this world. There are other simple inexpensive modelers also being used, such as, Alibre. Not to mention new comers, SpaceClaim.


Check out the image above of a Server Room. This is becoming more and more critical in the last few months. Large rooms with tremendous amount of heat being generated by rack after rack of computers. The rules of thumb just aren't cutting it. We recently visited a company where they were popping floor tiles up so that they can control where the air would go. Pretty crazy.

There is a huge push to make everything "greener". So, I suspect that HVAC guys will be out there searching for a solution. There are tools out there that are primed and ready to address the issues. Go check them out... http://www.cfdesign.com/