Sampling Repetitive Equipment
Many schools use large numbers of small HVAC equipment, such as cabinet heaters, reheat boxes, variable-air-volume (VAV) terminal units, fan-coil units, and exhaust fans. These items can be sampled to establish quality levels at a substantial savings compared with testing every single unit. Critical units should be sampled at a higher number than non-critical ones.
If no issues are found, comparable pieces of equipment likely have a similar high rate of accuracy. If errors are found, a new sample needs to be selected. If errors are found in the second sample, the entire lot should be tested.
Further, if a school only has two boilers, two chillers, two cooling towers, and six air-handling units, all of the equipment should be tested. If the school has 30 to 300 repetitive items, the equipment should be tested at a rate of 15 to 40 percent depending on criticality. More guidance on equipment sampling can be found in ASHRAE Guideline 1.1-2007, HVAC&R Technical Requirements for the Commissioning Process.
An RFP should include a table of planned equipment and sampling rates the CxA must satisfy. A difference in Cx fees of 15 percent vs. 100 percent of 300 VAV boxes is huge. An RFP also should state that repeat testing after the first retest will be billed to the installing contractor and that the CxA will be reimbursed for the extra time required on the job. This puts the cost incentive for quality squarely in the lap of the installing contractors and will level the fee programs from the prospective Cx providers.
The “deliverable” section of an RFP provides another pointed explanation of what is expected from the CxA. Typical deliverables include a review of the owner's project requirements, a Cx plan, a design-review report, Cx specifications, a deficiency database (updated weekly during functional testing), systems manuals, a final report, a training verification plan, an off-season testing plan, and a warranty walk-through report.
The Cx RFP is the first step in a successful school construction project. When an owner assumes responsibility for defining a project's Cx quality assurance, he or she takes the first step in controlling the quality of the finished building. Start Cx early and right with an accurate and thoughtful RFP, and a quality project will follow.
A commissioning project manager for AKF Group LLC, a full-service engineering firm, Ron Wilkinson, PE, LEED AP, is an authority on commissioning Leadership in Energy and Environmental Design (LEED) Green Building Rating System projects and sustainable buildings. He is the author of the first commissioning training program for LEED for New Construction and Major Renovations, the chair of the commissioning advisory committee of The American Institute of Architects (AIA) Committee on the Environment, and the recording secretary for American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) Guideline Project Committee 0.2/1.2, The Commissioning Process for Existing Building Systems and Assemblies/The Commissioning Process for Existing HVAC&R Systems. An ASHRAE Distinguished Lecturer and an AIA Continuing Education Lecturer, he has spoken on commissioning practices internationally. He is a longtime member of HPAC Engineering's Editorial Advisory Board.
ASSEMBLING A DEVELOPMENT TEAM
The team tasked with developing request for proposals for a school project should consist of:
- The district superintendent.
- A school-board member.
- A student representative.
- The district facilities manager.
- The operations and maintenance supervisor.
- An operations and maintenance staff member.
- A sustainable-design consultant.
- The project architect
(if already selected).
- The project engineer
(if already selected).
DOING THE RESEARCH
When commissioning (Cx) a school, several questions need to be asked. Try these for starters:
- What is the goal of the Cx process for this project?
- What equipment and systems must be included to meet the goal?
- What Cx tasks that must be included to meet that goal?
- What firms should be invited to propose on this project?
- What criteria will be used to select the Cx provider?