The use of building information modeling software when designing green projects is increasing as more engineers and mechanical contractors understand how BIM’s energy simulation and prefabrication components enable sustainable outcomes for large projects such as industrial buildings, schools and hospitals. This is the conclusion of “Green BIM: How Building Information Modeling is Contributing to Green Design and Construction,” a McGraw-Hill Construction SmartMarket Report.
“Concerns about climate change and energy dependence, as well as an economically driven focus on increasing efficiency and building performance in a cost-effective manner, have led many practitioners to adopt green-building strategies,” the report notes. “BIM adoption, while still relatively modest, is having a fundamental impact on design and construction practices. To fully realize the value of BIM, many firms are changing their approach to the process, with BIM enabling input from all players early in the design process, as well as allowing for greater use of prefabrication.”
The integrated design process that BIM facilitates is a perfect match for green design. Many of BIM’s tools, such as energy use modeling, provide better information for design and construction firms on how design changes affect building performance. And BIM provides more product information, allowing for more prefabrication, which eliminates waste and conserves resources, “making the construction process greener and faster,” the report explains.
Only 17% of respondents using BIM for green projects believe they take advantage of more than half the potential BIM offers to achieve their green building goals. The report notes that the rise in green projects could encourage greater BIM adoption as the construction industry better understands the potential of BIM for achieving sustainable objectives.
The key driver in the shift to sustainable construction is the owner. Many large corporations, as well as federal and state governments, have made commitments to greening their buildings. “As owners push for green buildings, other players will need to become experienced in delivering these projects — and delivering them on time and on budget,” the report explains.
More owners will be pushing BIM requirements for their buildings as they understand how BIM works to meet their sustainable goals. They’re also grasping how they can use BIM effectively during the operations and maintenance phase of a green building, in addition to the design and construction phases.
Mike McLaughlin, vice president of preconstruction at Southland Industries, and Chris Skoug, associate principal engineer at Southland, agree that building owners increasingly require BIM on their projects.
“The speed of BIM software development is tremendous,” Skoug says. Southland uses Autodesk Revit, and more features are added in every release. “It makes it easier for the end user to create an accurate model, whether you’re on the design side or the construction side. And building owners better understand the savings inherent in BIM so that contracts now better define the minimum content required. This may force the adoption of BIM if mechanical contractors aren’t already looking at it.”
Software integration is one area where green BIM practitioners see an emerging trend. It will allow project teams to use BIM models to compare real building performance results with initial estimates, according to the SmartMarket report.
“We’re starting to see some trends where separate design-based software and construction-based software are going to combine,” McLaughlin says.
The continually rising importance of energy efficiency across the country is reflected by the increase of engineers and contractors using energy performance simulations, the report notes. For those firms not specializing in sustainable projects, three main areas they would like to simulate using BIM include whole building energy use, energy code compliance, and lighting and daylighting.
Green BIM practitioners find the software particularly useful in retrofit projects, the report says. This could represent a strong growth area for BIM as the market share for green retrofit projects is projected to increase from 5% to 9% in 2009 to 20% to 30% by 2014.
“On retrofit projects where you’re dealing with existing conditions, it takes a major effort to model those conditions by hand,” McLaughlin explains. “But with laser-scanning technology, and the ability to import that information into a model, the adoption of BIM will continue to expand.”
Critical information
Southland Industries — No. 4 in Plumbing & Mechanical’s 2012 Pipe Trades Giants ranking — has offices in Garden Grove, Calif.; Union City, Calif.; Las Vegas; and the metro Washington, D.C. area. It was using an early form of 3D modeling in its construction/fabrication business back in the early 1990s. The push to use building information modeling in the engineering sector came in 2007. Southland brought BIM into its engineering business to stay at the forefront of this technology revolution.
“We did it not only for the 3D modeling but for the information embedded in the model that anyone can extract out of it,” Skoug explains.
This information capability of BIM is being used on a current Southland project — the new Carl R. Darnell Army Medical Center in Fort Hood, Texas. Southland is performing design-build mechanical and plumbing services for the 947,000-sq.-ft. hospital, which will replace the current 45-year-old hospital.
“On this project, room numbers, room square footages, ceiling heights, and all the individual equipment are modeled as elements or information that is readily extracted for anyone on the project team,” Skoug says. “We found ways to utilize that information for HVAC load calculations and room volume for air-change rates, which is a code requirement for hospitals.”
The coordination aspect of the 3D modeling that began in the firm’s construction work had a direct correlation to field productivity, McLaughlin says. On the Fort Hood medical center project, Southland was able to virtually coordinate utilities and avoid conflicts in the field that would waste time and money. With BIM on the engineering side, that coordination can be done much earlier in the design process to encourage prefabrication or modular construction opportunities.
“We can now influence the structure to reduce the depth of a steel beam to enable the ability to exit a shaft without lowering ceilings,” he adds. “And from a contracting standpoint, there’s information in the model that our field forces need to begin prefabrication and commission equipment.”
Hospital sustainability
The Fort Hood hospital is designed to achieve LEED Gold status as well as exceed the 30% minimum energy reduction of ASHRAE Standard 90.1. A remote central steam heating plant includes high-efficiency heating and cooling systems such as large Cleaver-Brooks fire-tube boilers, boiler stack economizers, high-efficiency centrifugal chillers and heat-recovery chillers.
The design calls for 5,400 tons of York water-cooled machines and Evapco cooling towers, which include a custom concrete-basin design to enhance maintainability of the condensor system.
The three-story main atrium, which connects the hospital to the clinics, has 25,000 sq. ft. of Uponor radiant floor heating in four thermal zones. Twenty Temtrol 45,000 cubic ft. per minute air-handling units are semi-custom designed and include fan wall technology to improve maintainability, redundancy and acoustic performance.
The most prominent feature of the system, McLaughlin notes, is the HVAC system, which uses 100% outside air in all patient-care areas for improved indoor air quality and increased energy efficiency.
“Southland believes the 100% outside air system is a superior choice for health-care facilities,” he adds. The company designed the same system for the Walter Reed National Military Medical Center in Bethesda, Md.
Another key feature designed for the Darnell Medical Center is the Integrated Building System concept, which includes a 7-ft. interstitial space — a hidden floor — above all patient-care areas dedicated to mechanical and electrical utilities.
“It’s a sustainable, life-cycle approach to designing a hospital,” McLaughlin says. “If you have a maintenance issue, you no longer have to move the patient out of the area. Maintenance staff can work on the repair without disrupting the patient-care activities. A lot of injuries to both patients and staff in health-care situations are the result of moving patients.”
While it’s a great benefit for hospitals, IBS did present some challenges during the Darnell Medical Center design.
“A tool like Revit is a real benefit with this type of design,” Skoug says. “With all the utilities that are intertwined in the interstitial space, we have to make sure the key components that require maintenance are accessible. We added an element into the model to represent the actual access aisle through the space. We use it to find and resolve any conflicts and ensure that when the final building is built out, it has a functional, maintainable and sustainable system.”
Building information modeling also helped in the logistics of the hospital’s design, since the plumbing design team is in Las Vegas; Skoug’s mechanical team is based in the metro Washington area; and the architect is in Dallas. Use of technology such as Revit Server enabled the team to efficienty collaborate during the design despite the physical separation.
