BIM: Proving Its Value
Switch Engineering was engaged to design a conversion an old air-side warehouse space into a 3,700 square foot walk in cooler for food cargo at the Edmonton International Airport. At the beginning of this project we chose to invest in a 3D point cloud, using a FARO Focus laser scanner, of the warehouse space. Each scan takes approximately 8 minutes to complete, and for the space - most of the day. This gave us a point cloud model of the pre-construction space with accuracy of measurements to +/- 1.00 mm.
Initially the design called for building the cooler interior to the space, including structural steel to support the cooler roof (made from insulated cooler panels). The cost for the structural steel exceeded the budget, therefore the client needed a different option. Switch Engineering suggested coating the interior of the existing warehouse with four to five inches of spray foam insulation, this took away the need for internal structures and increased the working area of the cooler. This meant that we needed to ensure that the existing steel structure and roof assembly especially could handle the new dead load of 4 inches of spray foam. One challenge of determining if the roof could accept the additional dead load was lack of as-built data.
Our structural engineer needed to measure the profile of the open web steel joists and reverse engineer the as-designed dead load. Typically in this situation, a site visit would be required by the engineer, a lift rented, safety protocols followed, and hand measurements taken along the length of the steel member. This time spent and equipment rental would be thousands of dollars extra that the client would have to pay. As well, tape measures have accuracy of +/- 4.00 mm at 8 meter measurements depending on their class and there is additional chance of human error. However, we had our point cloud ready for use. The Structural Engineer was able to create the profile of the open web steel joist, and as additional benefit see the bending profile of the joists under load allowing him to determine that the roof was not overloaded in the past. This was all done remotely using the point cloud that was generated.
Additional to greatly reducing the need for site visits for design verification, this point cloud scanner allows us to generate a very accurate BIM Revit model of the space to create drawings from and integrate with asset management systems used by the client. For this cooler we entered all model information of mechanical cooling equipment used here and directly integrated it into the format used by client's asset management system. This is especially valuable in situations like this where a retrofit project is on an old building with minimal to no as-built documentation.
From this positive experience we want to bring this value to all of our future retrofit projects and clients! And is the reason why Switch Engineering uses BIM in our work processes as a standard, and not as an additional service.