Scanning and Modeling Complex Building Systems for Renovation Work

Historically, complex building systems such as structural, mechanical, plumbing and electrical have been very difficult to document with any degree of dimensional accuracy. This is never more evident than when it comes to building renovation. Owners, architects, engineers and contractors rely heavily on whatever existing record drawing information they can find, and must field verify areas where data is unavailable or not trusted. However, todays technologies are making it much easier to document and represent these complex building systems and, as a result, are improving the process of renovation design and construction.

It is safe to say that the majority of buildings in our world today were designed and built utilizing two dimensional methodologies such as pencil and paper, or with 2D CAD (Computer Aided Design). As a result, most available record drawings are two dimensional representations of the real world.

With the advent and evolution of three dimensional technologies such as BIM (Building Information Modeling), we are seeing an increased demand to represent these complex real world conditions three dimensionally as they actually occur. It is much easier for a designer who is renovating a space to understand the constraints of routing new ductwork, piping and conduits through a building when they can see how they actually occupy the three dimensional space. However, the problem often faced is there is typically no three dimensional existing conditions data available.

Before they embark on their process of design they have a decision to make. Do they rely solely on existing two dimensional record drawings, some quick trips to the field with a sketch pad and camera, or do they embrace new technologies such as 3D Laser Scanning and BIM to help create an accurate existing conditions representation of the real world? There are pros and cons to both approaches.

By choosing the traditional process of working with the existing 2D documentation designers are choosing the more risky approach. The likelihood of costly change orders during construction is much higher since many of their design decisions will be based on assumptions made with inaccurate or unverified existing conditions data. Yet this approach is often still chosen in a rush to get started and to avoid the costs associated with surveying the space.

When the designer chooses to go the route of field verification there will be up front costs for the field survey and some initial time delays while the survey is being completed. However, with three dimensionally verified existing conditions, better design decisions can be made and the resulting reduction in construction change orders will usually more than compensate for both the added cost and time delays. Still, it can be a tough sell to spend more time and money up front for an unguaranteed payoff on the backend.

Laser scan imagery of complex piping systems

The above image is of a fairly congested utility tunnel on the campus of a large R&D (Research and Development) corporation. The tunnel joined the central plant building to various other buildings on the campus. A new three story building was being constructed that required routing new MPE (Mechanical, Plumbing and Electrical) systems through this tunnel to the new building. The challenge the design team faced was defining a path for the new systems to route. Unfortunately, they chose to forgo three-dimensional documentation and, instead, relied on the traditional process of utilizing 2D record drawings and visual field observation. In turn, their design drawings were created in 2D and didnt give the contractor a real world representation of how the new and existing systems would relate.

When the project went into construction the mechanical subcontractor was now tasked with the challenge of making it all work. How would they really route the new lines through the congested tunnel while avoiding clashes with the existing systems? The 2D construction documents showed the new utilities running easily through the tunnel in a straight line, but didnt represent the real world challenges faced of avoiding clashes with the existing MPE systems. The subcontractor decided the best method would be to utilize 3D Laser Scanning, create an existing conditions model and use it to create a construction model. The construction model would enable the subcontractor to figure out precisely where they could weave new lines in, out, around and through the existing systems. In addition, once this was done, they could even pre-fabricate from the construction model, helping to reduce the cost of construction and streamline the installation, thus shortening the construction schedule.

Creation of a geometric existing conditions model from point cloud data

Existing conditions model with point cloud data removed

While complex building systems have historically been very difficult to accurately document, technologies such as 3D Laser Scanning and 3D modeling are changing this. We are no longer dependant upon the traditional method of 2D field verification and all the risks associated with it. The use of these new technologies is vastly improving the process of design and construction of renovation projects, which is resulting in significant cost and time savings for owners, architects, engineers and contractors.