Single-Source Solutions: Using Your Experience (September 1999)
This culture change will be one of the biggest hurdles for D-B firms to overcome. To date, there have been very few hvac companies to make that change.
Go With The FlowIn partnering with construction companies, there seems to be reluctance on the part of the contractor to begin the process with the knowledge and confidence that they can achieve this goal.
Maybe the problem lies with the hvac contractor usually following the directions of a general contractor that prevents them from changing the way they do business. Maybe they are just not ready to accept the lead role. Whatever the reason, hvac firms are in the ideal position to take responsibility and control of a project based on their experience and ability to competitively estimate the job, without the traditional 80% to 100% complete construction documents. In doing so, they would now be in the position to begin the record-drawing process in the conceptual phase of engineering design.
Having made this intrepid statement, the question is then asked, "How do you do that?" The answer is in the approach to D-B, or more specifically, the approach to construction documentation.
For the task of completing record drawings, the D-B engineer should always begin with a system flow diagram. Using a chilled-water system as the example, the flow diagram shows all the equipment (i.e., chiller, pumps, cooling coils).
With this "big picture" image, the engineer can now freehand sketch the routing of pipe on a set of building floorplan drawings. It is at this point that an experienced D-B estimator can establish relatively accurate installation costs for the layout without having final computer-aided piping drawings. More importantly, the pipe route is known, the pipe sizes have been established, and the approximate lengths of pipe are also known. What is missing is the final coordination.
A Picture Of EfficiencyIncluded with the pipe distribution and freehand sketches should be some standard details. Here again, the experienced estimator can draw upon a select few details to make this estimate more accurate, and the paper trail can be found by simply attaching these 81/2- by 11-in. details to the flow diagram sheet and piping layout plan. The construction documents are still in the sketch phase, and yet the D-B firm now has the documentation, experience, and confidence to provide a guaranteed price to complete this portion of the work.
At this point in time, the D-B firm has a detailed scope of work, and a written narrative can be added to complete the D-B proposal. Don't forget to complete the sequence of operation and commissioning verification test procedures. All this work can occur within the first 5% to 10% of a building program - well ahead of the more traditional design-bid-build, or construction management process.
As the project moves forward into the construction phase, the freehand sketches are used to begin the field coordination drawings. It is at this point in time that CAD documentation can begin. Completing the record drawings as the hvac system is being installed provides the D-B firm with ample time to complete the project without compromising a fast-track project time schedule. The day the job is finished is the same day the record drawings are finished.