A look at some of the building information modeling images used by Straus Systems for its projects.

Founded in 1933, Straus Systems designs, fabricates and installs heating, ventilating and air-conditioning systems for many commercial and industrial clients in and around the Houston area.

Much like other engineering fields, mechanical contractors rely on information technology in the way of 3-D computer-aided mechanical and drafting software to design and fabricate increasingly complex systems.

Now, with the introduction of building information modeling tools, techniques and methods, Straus Systems has begun to expand its capabilities to meet customer demand for the use of “intelligent” 3-D models in construction.

Paul J. Alexander, vice president of Straus Systems, said the move to BIM did not scare company officials.

Shifting methods

“In terms of technology adoption, the shift to BIM as a design-fabrication tool is not a big deal for us,” Alexander said. “The greater challenge is finding ways to use the 3-D data and models to drive efficiency and accuracy at the jobsite.”

For every pipe and duct in a HVAC system, there are numerous hangers, sleeves and other apparatus that must be positioned within the structure to support the systems and avoid other building components.

Typically, Straus Systems’ piping and sheet metal CAD drawings incorporate the hanger and sleeve locations. Currently the firm uses AutoCAD MEP 3D, QuickPen DuctDesigner 3D and QuickPen PipeDesigner 3D, Navisworks for clash detection, QuickPen AutoBid SheetMetal and QuickPen AutoBid Mechanical software, as well as interconnected Vulcan CAM software in its manufacturing plant.

Field crews, however, still typically rely on conventional tools and techniques, such as stationery lasers, string lines and plumb bobs, to locate pipe and duct hangers and sleeves on a jobsite.

“With the advent of BIM, locating points is simply not enough,” Alexander said. “We have the opportunity to locate positions with greater accuracy and then update the model to reflect as-built conditions.”

The piping that existed on a roof where Straus Systems was to design, fabricate and install a new water and steam pipe rack for a client. The company used BIM on the project.


To facilitate this speedier, more accurate process, Straus Systems purchased several Trimble MEP layout products, which includes the Trimble RTS Series Robotic Total Station and its MEP layout software.

With the robotic total station, crews download the hanger points from the CAD model into the MEP layout software. Once benchmarks are established, they use the robotic total station to “shoot” hanger points using the laser.

Straus officials were pleased.

“We couldn’t believe the improvements in speed and accuracy,” Alexander said. “Using the old methods, a two-person crew could lay out 100 hanger points in an eight-hour day. With the robot, we can layout 400 points a day - and we are very accurate. We can measure positions to within one-sixteenth of an inch at 600 feet.”

The firm has since demonstrated the benefit of both BIM and robotic technology on two distinctly different projects: a petroleum research complex and a university lecture hall.

Rack installation

An oil and gas client in the Houston area contracted Straus Systems to design, fabricate and install a new water and steam pipe rack that was to be located above an existing rack. The new rack will span approximately 700 feet across existing rooftops, connecting to a new facility.

For the pipe rack, the first step was to determine the exact location of each existing rack support. With the station, crews were able to collect the existing hanger pipe locations using the robotic total station and upload the data to the 3-D CAD model, where designers could position new pipes to fit the given space.

Alexander said the new BIM systems helped.

“While it’s difficult to quantify how much quicker we’re capturing data on an existing project or the value we’ve gained from that efficiency, there is no question that we were at least two to three times faster as compared to our previous methods,” he said.

Straus Systems crews found similar advantages during the construction of the Michael J. Cemo Hall at the University of Houston.

To create and place the underground ductwork needed at the University of Houston’s $9 million Michael J. Cemo Hall, Straus Systems used 3-D CAD and Trimble’s Robotic Total Station with MEP layout.

School work

This $9 million Michael J. Cemo Hall project includes a 34,000-square-foot building with a 400-seat lecture hall, three 80-seat classrooms and an academic center.

Straus Systems crews set 396 sleeves for 6-inch round floor diffusers in the lecture hall. The room was round with radius-raised tier seating. Sleeves were located under the seats and would eventually receive air diffusers.

Layout work would have been very time consuming using conventional means. To complicate the issue, the seating arrangement changed at the last minute, causing all the sleeves to be relocated.  The task that would have taken three or four times as long was accomplished in a day and a half. Using 3-D CAD and the Robotic Total Station with MEP layout made short work of the task.

“The digital connection we’ve created between the 3-D model and the field opens up so many opportunities for us,” Alexander said. “There are many applications where we can capture existing as-built conditions and import into our 3-D model to use in design efforts.”

For example, Straus Systems is increasingly called on to help with renovations and rehabilitations and industrial processing plans. In these cases, crews must remove and replace equipment.

“We can capture existing points, wall penetrations, floor penetrations, piping penetrations, and ductwork positions with the robotic laser, upload the data to our CAD department’s ‘CAD cave,’ and design a best-fit solution,” Alexander said. “We foresee many other uses for this type of equipment, including layout of underground work. The digital connection this tool creates between the 3-D model and the field is invaluable, opening up new opportunities to improve efficiency and accuracy.”

This article and its images were supplied by Trimble. For reprints, contact Jill DeVries at (248) 244-1726 or email devriesj@bnpmedia.com.