John Jurewicz, AIA

John Jurewicz has 20 years of project management experience, with emphasis in architecture and construction management. In addition to running an architure firm in the historic town square of Woodstock, Ill., Jurewicz teaches courses in Building Information Modeling implementation at Northwestern University and College of Lake County. He is currently writing a book on the benefits of BIM for contractors. Jurewicz can be reached at jj@aarchitects.net.

By John Jurewicz

In this continuing series on the realities of achieving LEED credits with BIM, I delve into the strengths and weaknesses of the 15 most commonly used programs for energy simulation of building models. You may not be surprised to learn that many of the programs most often advocated by larger vendors are expensive, but did you know that these same programs don't usually achieve anything meaningful for BIM model interactions? If that surprises you, consider this: Freeware and less expensive programs developed by research groups do well with energy analysis. And, they have good visuals.

Government-Driven Tools
Last month, I cautioned against over reliance on computer programs that are used to achieve LEED credits. There are two camps that suggest how these programs evolved. Our first group includes analysis programs that have developed from the mother of all analysis programs -- the U.S. Department of Energy (DOE) and the Lawrence Berkeley National Laboratories (LBNL).  These include (listed in order as they evolved):

• DOE-2 -- The DOE's eponymous building energy use and cost analysis software
• TRYNSYS -- Transient Energy System Simulation Tool, developed by the University of Wisconsin
• BLAST -- U.S. Army Construction Engineering Research Laboratories' (CERL) Building Loads Analysis and System Thermodynamics
• Energy-10 -- Sustainable Buildings Industry Council's (SBIC) energy simulation tool
• EnergyPRO -- EnergySoft's energy performance modeling software for California's Title 24 compliance
• eQUEST -- DOE-2's Quick Energy Simulation Tool
• VisualDOE -- Architectural Energy Corporation's energy simulation and design tool
• Green Building Studio -- Autodesk's web-based energy analysis service
• EnergyPlus -- a merger of DOE-2 and BLAST
• Ecotect -- Autodesk's environmental simulation and design analysis tool

Most of these applications offer free trials, but only two, eQUEST and EnergyPlus, are truly free. These two programs are version of DOE-2 most commonly used by professionals that analyze for LEED EA Credit 1 (energy optimization) to run comparisons against a baseline.

If you are willing to spend a little money (up to $500), several of these programs offer visualization tools that make them much easier to use, especially if you lack training in thermal dynamics engineering. This subgroup of visualization tools includes Visual DOE, Green Building Studio and Ecotect (Figure 1). These tools are by far the easiest tools for users new to the energy simulation world and are geared for designers who think visually.

eQUEST 3.55 (Figure 2, at right) combines design wizards with an energy efficiency measure (EEM) wizard and graphs out a display per the DOE algorithms.

VisualDOE (Figure 3, at right) is more comprehensive. In addition to the envelope, it includes lighting, water heating, the central plant and HVAC systems. This analysis tool qualifies for the EPACT 2005 IRS tax deduction.

VisualDOE is a graphics, forms and reports interface to the DOE-2.1E program (the industry standard building energy simulation program), developed by the DOE and Lawrence Berkeley National Laboratories. With VisualDOE, users can quickly create design alternatives with energy conservation measures and evaluate their impacts on building energy use and cost. Powerful and handy features are built into the program to help users quickly create baseline buildings based on energy codes and standards. Special features are included for LEED energy savings calculations and reporting.

Industry-Driven Tools
The second group evolved from industry-specific research, such as that conducted by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE):

• SPARK -- LBNL's Simulation Problem Analysis and Research Kernel
• HAP -- Carrier's Hourly Access Program for HVAC systems
• IES -- Integrated Environmental Solutions' virtual environment building performance simulation and energy modeling software (VE-Ware)
• TRACE 700 -- Trane's HVAC load, system, energy and economic analysis program

The favorites among HVAC designers are Trane's Trace 700 and Carrier's HAP programs, which both have easy-to-complete LEED templates. Of these two, HAP is more widely used (with 5,000 registered users), whereas Trane's Trace runs a distant second (1,000 users), according to research posted on the DOE's website (1).  It takes mechanical engineering experience to use these programs properly, and they are geared for sizing equipment. As stated in previous articles, only Trane is bi-directional with BIM. Unfortunately, it is not very interactive unless certain modeling techniques are set up, which requires training.

Ease of Use
I teach and have access to an inexpensive labor pool of eager engineering students, whom I used to run basic trials of the aforementioned programs. We downloaded each program and ran it through basic trials of analyzing a generic one-story, 8,000-square-foot building, located in the Midwest. We rated these programs on their intuitiveness and ease of understanding, with cost not the chief criteria.

We based our conclusions on the following three criteria:

1. Ease of use in following workflow
2. Ease in entering inputs
3. Ease in getting the information needed to complete LEED templates

The following is what we found. For first time users, Autodesk's Green Building Studio was the easiest to use for those trained in the architectural profession.  For those with some background in engineering, the favorite was VisualDOE. And lastly, for those sizing and specifying mechanical systems and trained as mechanical engineers, HAP was the system of choice.

Most engineers tasked with running comparisons between the proposed designs and the baseline for energy optimization preferred Carrier's HAP tool (Figure 4, below). Although it has limits for research, engineers enjoy how it makes the technical aspects so easy. Its functionality follows DOE 2.1 but differs in that it has improved graphics, reports, data management, online help and reports that are easy to generate for performance data via electronic link for Carrier equipment.

End Note
1. In my July 2009 article, I wrote about radiance a lighting calculation tool and referenced GE's free electrical cost calculator. Next month, I shall demonstrate the use of these tools and my experiences on a live project.