IES and LEED Energy Modeling

For a couple years now many IES has placed much of there development efforts towards compliance with the Performance Rating Method of ASHRAE 90.1 (LEED Energy Modeling). What we saw during this time, however, was mostly a new look and more of those buttons. The most frustrating part was that IES had LEED written all over their product, being able to demonstrate compliance on a large number of credits.

Wait a minute. The single largest point getting credit in the LEED Rating system, not to mention the largest consulting fees for any one credit (over 100K depending on the project), is EA1 Optimize Energy Performance, and the use of an ASHRAE compliant energy model can get you the most points. Energy Modeling, that's the business. And what is IES? It's an Energy Modeling software. Wait, what?

Now, several years later, they've done it. Finally, thank you!

Why did we like IES in the first place? Because it's a visual, multi-purpose engineering and analysis tool that inter-operates with BIM. So how then do you take a BIM model into IES for LEED energy modeling?

Everything has changed, and you'll have to wait until my next post to hear about it. ;)

Design Builder!

With the growing emphasis on energy efficiency and Integrated Design, we are seeing more and more tools emerging to aid in energy efficient design analysis. Design Builder isn't entirely new, but after last year's added gbxml functionality, Design Builder has become a very capable addition to the Integrated Design toolbox.

Much like IES and eQuest, Design builder is a heavy-duty energy modeler that markets itself to both architects and engineers. Since it isn't the intent of this blog to compare or evaluate multiple applications side by side, I will only mention what I believe are the strengths of Design Builder, and where I think it can still improve.

Strengths:

• Energy Plus Design Builder is built on top of the Energy Plus simulation engine, arguably the most powerful and innovative energy modeler in the industry.
• Ease of Use The hierarchical structure between project/building/zone makes it easy to edit variables and assign data (such as material properties, space properties, etc)
• Templates While I wouldn't say that the template database is entirely comprehensive, it is very good. Particularly useful are the "early design" defaults.
• Daylighting and Energy Placed sensors can calculate daylight levels and adjust the natural light levels accordingly. This functionality is somewhat of a breakthrough when compared to earlier methods using approximated daylight factors, or requiring daylight autonomy calculations to be manually fed between a daylighting analysis tool and the energy modeler.
• Airflow and Energy Advanced functionality in Energy Plus can calculate bulk airflow between zones and building openings in a detail, rather than with an approximated or scheduled method. At an early stage in design, scheduled air changes per hour (ACH) can be good enough, but for detailed design verification you want more sophisticated analysis capabilities.
  
• CFD A separate CFD module utilizes the same geometry from the energy model. I've not tested this yet so I will reserve comments until later.
  
• Interoperability Design Builder imports gbxml file formats! At times it takes a mess of imperfect zones and simplifies them very rationally. Other times, when you import a fairly clean model you can sometimes simply miss a zone. The import process still needs development to be completely reliable, as with many other analysis tools?
• Shading Recent updates to shading object importing now allows Design Builder to import gbxml shading objects, such as overhangs, surrounding buildings, etc.
  

Finally, Design Builder is particularly useful when comparing simple building forms in a way that acknowledges the specific impacts of building form on relevant green design strategies, or Energy Conservation Measures (ECMs). I'm attaching a link to a research project done by Ryan Meyer, a Graduate student in the civil and Architectural Engineering Dept at the University of Wyoming.

Form Energy Analysis

Keep up the good work!