Plan for HVAC Lifecycle Performance During Design

HVAC systems for commercial buildings are expected to last 20 years or more. But improperly designed, installed, operated, or maintained systems last far less and cause a lot of expensive problems along the way.

Building lifecycles have several phases that can be generalized as:

  • Design
  • Construction
  • Operations & Maintenance
  • Decommissioning/destruction

The design phase itself could be considered as multiple phases, including pre-design, where owners and engineers agree on the basis of design for the facility and how it will be operated; design phase, where the design is iteratively developed; and commissioning, where the design is coordinated with an independent third party to ensure the basis of design is met.

The design phase also includes considerations for the downstream lifecycle phases – construction, O&M, and decommissioning.

Design for construction ensures a design is, well… “constructible.” What looks good “on paper” might not work in the field.  There might be missing elements, conflicts among systems, especially in tight spaces such as ceiling plenums, or impossible means of getting equipment in or out of a space.

Design for O&M is critical, but often overlooked. A lot of filters, sieves, valves, and dampers are clocked, stuck, or broken because operators can’t get to them easily, or if there’s not enough room to get an access door open. This happens all the time.

Another important lifecycle consideration is having adequate documentation and operator training. If you throw the keys of a new Mercedes to someone who doesn’t know how to drive it, what do you think will happen?

Where lifecycle issues come home to roost is in operating costs. Good lifecycle design minimizes energy and water consumption, saving utility costs. Also, equipment life is lengthened and downtime is reduced. Meanwhile, occupant complaints are fewer and asset value of the building is higher. These benefits greatly outweigh upfront costs of paying designers more for the time they would take for more robust designs. After a building is constructed, even simple solutions, like reorienting an air handler 90-degrees, could cost a fortune.

A lot of these considerations are discussed in the Whole Building Design Guide (WBDG), published online by the National Institute of Building Sciences (NIBS), the goal of HVAC lifecycle performance optimization “is to provide an indoor environment that allows for maximum occupant effectiveness while minimizing energy, maintenance and operating costs.”

Another good resource is a blog by expert commissioning provider and trainer, David Sellers, PE, senior engineer for Facility Dynamics Engineering. In one of his posts, “Projecting Building Maintenance Costs,” Sellers explains how to project future maintenance costs, and he points to online resources to assist engineers in doing so.

Remember- lifecycle performance requires a lifecycle perspective during the design phase?

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