Energy modeling software has become quite important in the last decade, mostly because of the LEED credits involved with energy usage (and the need to reduce long-term energy use because of costs). Energy use estimations in these cases have tended to be inaccurate, for as of yet unknown reasons. The USGBC is now mandating energy use reporting periods in order to track down the problems, and I have no doubt that eventually the problems will be found.
Energy modeling is still a very useful process. If for nothing else it makes you think long and hard about decisions that were once hidden behind a veil of complexity. Lighting issues matter, HVAC issues matter, renewable energy sources matter. With a little bit of attention and ingenuity, our buildings can start saving money and emissions from the first day of operation.
Software that allows one to calculate the true effects of every project decision is somewhere in the region of non-existent or too expensive. But we have great reason to celebrate, because energy modeling is about to become widely available and much more accurate.
The US Dept. of Energy has been steadily working on their EnergyPlus program for several years. This program is the calculating engine behind most of the software packages today. It incorporates everything that people know about heat transfer and energy usage. The one thing missing is a Graphical User Interface. Previously there was only one option if you needed a GUI – you can purchase a commercial package such as offered by Bentley, Autodesk, or IES.
If you can can’t afford this, or are just looking to play around with some fun freeware programs then I strongly suggest everyone investigate the new SketchUp plugin IES-VE Ware. With this setup, you can draw a design in SketchUp and do limited energy analyses with the plugin. It won’t be enough to estimate your monthly bill, and certainly nowhere near the sophistication needed to qualify for LEED points, but it’s a good start. (see the plugins at SketchUp’s own site)
It’s only a rumor, but I have heard that ASHRAE believes a new user interface for the EnergyPlus engine will become available within the next year or two. This would usher in a new era of energy modeling of the people, by the people, and for the people! Keep your fingers crossed, we may get lucky.