This month, I’m extending my discussion from last month’s column on contract documents that consulting engineers produce for construction jobs. This series also builds off my December feature article on integrated project delivery (IPD) and can be applied to the other three other project delivery methods: design-bid-build, construction management, and design-build.

You could say I’m on a mission to encourage design engineers to “break the mold” on how they separate portions of equipment specification, e.g., chiller schedule sheet, automatic control sequence of operation with system flow diagram, and standard piping details with contract drawing documents. In addition, the commissioning functional performance test (FPT) narrative will be found in another section of the contract specification manual.

Here, I’m advocating contract drawings that provide (1) equipment schedule, (2) standard detail sheet, (3) system flow diagram, and (4) automatic control sheet be embedded into the contract specification document. Remember, time is money, and with every additional contract drawing produced, it takes time and design fee to dissect the HVAC equipment information into the contract specifications and contract drawings. This cost to produce these four sheets can be avoided. My value-added approach is easily achieved. To do this allows the design engineer to actually reduce his or her effort with the results being a potential increase in the design fee profit. *See attachment titled “Equipment Specification Template.”

Consolidating all equipment information within the project contract specification rather than splitting it up across different contract drawings requires a culture change for the designer, and change is usually difficult to embrace. This approach will also be a culture change for the contractor and subcontractors. But the result should be an increase in design fee profit and the ability to find information — criteria requirements, specification, specific installation details and coordination, and even startup and commissioning — for each piece of HVAC equipment in a single location.

Since I began designing HVAC systems and producing contract documents, which have always consisted of construction drawings and specifications, there have been industry standard production procedures to producing these documents for a building program. When it comes to writing the HVAC equipment specification along with the associated automatic control sequences of operation, the design engineer will exclude much of the equipment criteria and place it in the contract drawing documents. He or she will take pertinent equipment data and create a contract drawing “schedule sheet,” and based on the number of pieces of equipment, there is usually more than just one contract drawing titled “schedule sheet.” With each type of equipment, there will usually be standard details cut and pasted on to a “detail sheet” and, again, multiple contract detail sheets are produced.

The designer further separates the HVAC equipment data, producing one or more contract drawing documents, titled, “automatic control system drawing and flow diagram.”

To summarize, and using an HVAC chiller as my example, we have the following:

  • Equipment Specification in the contract document specification manual, minus the equipment performance data, such as model number, size, capacity, etc.
  • Equipment Schedule Sheet in the contract drawing documents providing the bidding contractors specific performance data.
  • Automatic Temperature Control System Sheet in the contract drawing documents, possibly with the control system flow diagram embedded into this drawing or on another drawing showing the system flow diagram.
  • Detail Sheet in the contract drawing documents providing the bidding contractors specific installation requirements.
  • Commissioning Specification where the equipment startup and functional performance test narrative are located.

The value-added solution to this specification drawing separation is to keep all this data, e.g., equipment specification, equipment schedule criteria, and the equipment’s ATC system flow diagram and sequence of operation together in the contract specification document. This eliminates the equipment schedule sheet(s) and the ATC system sheet(s) with its flow diagram and sequence of operation narrative. To take this value-added suggestion further, the standard equipment piping or sheet metal detail, found on contract drawings titles, “detail sheet,” can be included in the contract specification document too. The final arrangement would look something like this:

Contract Specification:

  • A. HVAC Chiller shall be: 300 ton, based on manufacturer “ABC” shall be variable flow chiller, etc.
  • B. Chiller Performance Data: 300-ton chiller, model “XYZ” shall be 600 GPM, 12-foot pressure drop, etc.
  • C. Chiller System Flow Diagram: 300-ton chiller flow diagram shall include the following sequence of operation beginning with sequence 1-System at maximum capacity, etc.
  • D. Chiller Installation Detail: (insert standard detail) showing all required piping, refrigerant alarm(s), etc.

Important information that often falls through the cracks when producing contract documents is where the equipment manufacturer’s ATC requirements begin and end when coordinating “work by others” with the prime contractor’s ATC subcontractor’s contract specification requirements and what is shown on ATC system flow diagram contract drawings. For example, who is responsible to provide the chiller’s ATC panel with the project’s building automation system (BAS) computer: the project ATC subcontractor or the chiller manufacturer’s ATC technician? This can be coordinated and posted in the equipment specification along with other subcontractor requirements.

In recap, keep it simple — combine contract specification with associated contract drawings.