Energy Modeling Software

As LEED reviewers we most often see eQUEST, Trace, HAP, EnergyPlus, Design Builder, and IES-VE. There are a few others that we rarely see. In our practice we mostly use eQUEST and occasionally Design Builder. 

We used eQuest for many years, but have used IES-VE for the past 10 years or more.   The upfront cost for eQuest (FREE!) is quite attractive, but the technical support is worth only slightly more than what you pay for it.  There are some training resources from third parties and user manuals, but you generally have to throw yourself on the kindness of strangers that monitor the bldg-sim list serve for "real time" tech support.  I can't say enough about the kindness of those strangers, but when you are trying to debug a model in the wee small hours of the morning, waiting on a stranger to read your help request is not a comfortable place to be.  Also, while eQuest is occasionally updated, we felt like the work arounds for novel systems (like VRF, for one example) left something to be desired.  Also, in the interest of reducing calculation intensity, eQuest makes some "conservative" assumptions that tend to yield higher results than other programs.  We don't like to have to leave LEED points on the table. We don't use energy simulation software that is written and sold by companies that manufacture and sell the equipment and systems that you are trying to model.  While there are frequent disclaimers about "firewalls" to limit conflict of interest, we'd just rather not have to figure out if that chiller really does need to be 1000 tons instead of 900. We have settled on IES-VE, and don't expect to change for the forseeable future.  While it is not free, we find that the technical support and frequency of updates justify the cost.  The learning curve is not extremely steep, but the program still has enough power and complexity to model just about any geometry or system type, as well as incorporate complex operating schedules and control schemes.  Since the calculations don't cut any corners, the time to run a large and complicated model can be long, especially on an underpowered processor, so besides the investment in the software, you may find that you need hardware investment as well.  We also like the inclusion of related simulation programs (like natural ventilation and daylighting analysis) that integrate well with the energy modeling modules.  Unlike the Energy-Plus based programs (for example, Design Builder), we rarely have to write customized code so that IES-VE can handle unusual circumstances.  The IES folks are extremely helpful and responsive and have updated the VE in response to our feedback many times.

Apart from the usual suspects listed above (eQuest, IES-VE., design builder), I have also used OpenStudio and EnergyPro. I would not recommend EnergyPro for LEED specific  purposes and I am fairly new to Openstudio.