At IBE Consulting Engineers, we were designing the mechanical, electrical, and plumbing (MEP) systems for a courthouse in California, when we noticed an unusual spike in energy consumed for cooling in the late summer weeks. As engineers devoted to sustainability, we run frequent load calculations and space analyses that are based upon standard Building Information Modeling (BIM) software. Seeing the increase, we turned to the BIM model to examine the cause of this spike, which was too high to be explained by hot weather alone.
One benefit of BIM is the ease in which we can relate a building’s orientation to the sun’s seasonal paths across the sky, and plot the resulting energy use given factors such as the building’s geometry, orientation, fenestration, and U-values (insulating properties) of its walls. Prior to BIM, validating performance model inputs was time consuming and produced more opportunities for misinterpretation of information. For this project’s analysis we used Autodesk Revit and exported data to Trace for load and energy-use calculations.
Reviewing the results produced from the analysis obtained using BIM, and focusing on the suspected hot room in the courthouse, we found the reason behind the spike: There was a window into which sunlight poured directly for only a few hours each day during only a few weeks each year. We consulted with the architect, and were able to arrive at a solution well before the design process was mature. This behind-the-scenes ability to locate and fix problem areas early is an often overlooked aspect of sustainable design, but in the long run it can save time, materials, and money.
The energy spike in the courthouse, and the resulting fix, underline several strengths of BIM as it relates to sustainable initiatives. Energy calculations performed as often as necessary can inform owners and architects early of potential problems. Also, what-if scenarios can be fruitfully explored. Studying sun paths and the resulting energy loads is just one area that lends itself well to using BIM to explore possible solutions.
On a larger level, coordination among engineers, architects, and owners in the design stage means that green initiatives are embedded early into the building design process, thus minimizing conflict with other building goals. We are beginning to see that green initiatives are not seen as supplemental, but as intrinsic, to a project. Increasingly, building owners seize on green initiatives in an effort to cut gas and electric bills.
Beyond the design stage, BIM aids communication with all parties, including contractors who benefit from seeing the design in a more concrete, less abstract way. It can also aid in the reduction of jobsite material waste through better scheduling and construction management. Early proper placement of mechanical equipment and roomsallowing for ease of access, future upgrades, and reduced system disruption—is another result.
IBE supplements BIM with Trace, a program that calculates a building’s probable energy consumption. We export certain data from BIMsuch as building size, orientation, and U-valuesto Trace to run load or energy-consumption calculations. We do this because BIM software does not directly calculate probable building energy consumption. From an engineer’s perspective, the idealperhaps an on-screen box that presents projected energy consumption as design changes are madeis not yet a reality. Software developers have made advances in providing rapid feedback for early prototyping, but these platforms still lack the detail and flexibility to explore nontraditional systems and design alternatives. As it stands, several software developers have developed plug-ins that integrate into Revit to allow information in a model to be exported to the secondary platform for further calculation. Some of these calculations can then be populated back into BIM for use in design layouts.
But technology alone is not a panacea. Rational, nuanced thought, the kind BIM cannot do, is required. Both architectural and systems designers must be experienced enough to know the various passive, active, and environmental factors that can influence the building’s energy use over time.
The next steps should be to take BIM beyond the design and construction phases and place it in the hands of the owners, who could then use the information to remodel, maintain, and operate the building long after the designers and builders have left the site. Integration with an owner’s maintenance and controls systems would add an additional level of management, but it also would provide facilities with greater insight and a single source for complete building information. While some owners are making this integration now, it is not yet at a plug-and-play level. In the very near future, however, building performance, maintenance information, and controls will become an integral part of BIM. This will yield buildings that are not only designed with a sustainable and integrated approach, but are also run efficiently, with continual monitoring and opportunities for incremental upgrades as new opportunities arise.
As BIM matures, more clients are becoming familiar with its attributes. That should lead to greater use of BIM, and earlier insertion of MEP engineers and sustainable initiatives into the design and construction process. But, like most tools, BIM is only as good as the people who use it.
Bungane Mehlomakulu, IBE Consulting Engineers principal, specializes in advanced building systems, design technologies, and radiant, displacement, and passive mechanical systems. Natalia Khaldi, IBE Consulting Engineers’ BIM manager, trains MEP engineers in BIM, and manages the delivery of engineering design drawings and BIM models to clients. Visit IBE Consulting Engineers at ibece.com.