ASHRAE’s 2020 HVAC Systems and Equipment Handbook, Chapter 1, may be considered the cornerstone to producing the optimum HVAC system selection for any building owner. Why’s that? Well, it’s provided design engineers with a multitude of questions they will need to systematically analyze and solve on behalf of a respective building owner’s HVAC and process heating/cooling project goals.

The chapter is easy to follow, both for design engineers and building owners and/or owner representatives, beginning with project goals and design intent, including but not limited to criteria, such as:

  • Building space pressure;
  • Minimum air changes;
  • Redundancy; and
  • Sustainability and life cycle.

The list shown on page 1.1 of the handbook can easily be expanded for a specific project to address current event topics, such as security and resilience, (refer to Scott Campbell, Ph. D., P.E.’s monthly column in Engineered Systems magazine). In addition, this chapter raises awareness to additional “soft” goals that focus on owner-specific aspirations, e.g., promoting public image for the building, increasing marketability of leased space, etc.

The next topic in this chapter, equipment and system constraints, aims to raise designers’ awareness, helping them to not overlook equipment and system challenges, especially when the project is a renovation within an existing building.

I spent my first eight years in the consulting business designing HVAC systems to fit within existing buildings. Through that experience, I quickly realized some building owners and facility managers weren’t good at reading contract drawings, but they were quick to note that an existing beam was preventing the equipment from being installed, saying to the designer, “That equipment can’t fit under the beam. Didn’t you see it and measure the depth of this beam versus the height of the equipment?” Hindsight is always 20/20.

A similar topic follows equipment and system constraints with “Constructability Constraints,” raising questions, such as, “Does the existing floor have the structural capabilities to hold the weight of the new piece of HVAC equipment?” Both “constraint” topics raise awareness to all on the building program team of issues and concerns that must not be overlooked. Even new buildings can have constraints, e.g., the project is going to take 18 months to build, and the client needs the building in operation within 14 months. Depending on the situation, solutions can be built into the design and construction, such as prepurchasing long equipment lead items or phasing the building so certain portions of the facility will be in operation by the 14-month marker.

When considering a few different HVAC systems for the application based on the above, these systems will have pros and cons and can be categorized into good-better-best system recommendations to present to the building program committee when following the process outlined in Chapter 1, “HVAC System Analysis and Selection.”

The discussion centering on “narrowing the choices” in this chapter provides designers analytical scoring methods to present to clients, which simplify the selection of the optimum HVAC system for the application. This is why it is the cornerstone of producing the optimum HVAC system selection for any building owner.