ASHRAE Journal - December 2019 - 54

COLUMN ENGINEER'S NOTEBOOK
Steven T. Taylor

Value-Based HVAC
Equipment Selection
BY STEVEN T. TAYLOR, P.E., FELLOW ASHRAE

How do HVAC designers select HVAC equipment? Ideally, equipment selection
would be based on total life-cycle costs, but that seldom is the case. More commonly,
equipment is selected based on the designer's past experience and familiarity with
the product or low price. In this month's column, I will outline a better and more
transparent approach to equipment selection that provides a more effective balance
between ﬁrst costs and equipment features and performance.
Current Practice
On design-bid-build, aka "plan & spec" (p&s), projects, equipment selection can be somewhat arbitrary.
The designer usually uses products he or she is familiar with from past experience with similar projects,
perhaps inﬂuenced by recent articles in professional
magazines or recommendations from a supportive sales
representative (rep). Seldom is equipment priced prior
to selection. In fact, once listed in the equipment schedule, the product immediately becomes more expensive
than it might otherwise be because the "basis of design"
equipment selections end up being purchased most of
the time. This is because contractors do not want to take
on the liabilities and responsibilities of an alternative
product ("substitution"), including secondary impacts
such as changes in size, weight, power requirements,
etc. Sales reps know this, so the scheduled equipment
can be sold for a higher price. If the product is unique,
the total price of equipment can be still higher if the
rep "bundles" the equipment with other products he
or she represents. If the speciﬁed product is signiﬁcantly more expensive than alternatives, contractors
will often propose a substitution, but this can result in
54

ASHRAE JOURNAL

ashrae.org

D E C E M B E R 2 0 19

arguments between the contractor and engineer about
what is "equal," multiple submittal reviews, revisions to
construction documents, all requiring additional time
on everyone's part. Ultimately, with this approach, it
is unlikely that the purchased equipment was the best
selection for the project or purchased at the best price.
This is not an effective way to select equipment.
On bid-design-build, aka "design/build" (d/b), projects, if there are detailed bridging documents or speciﬁcations, the equipment may already be selected with
the same disadvantages as described previously for
p&s projects. If the bid documents are lean and the d/b
contractor is selected based on their low bid, then the
equipment is usually also selected based on low price.
Again, it is unlikely this results in the best equipment
selection for the project.

A Better Approach
A better approach is to make major equipment selection a team effort, where the contractors, design engineer, owner, and any other members of the design
Steven T. Taylor, P.E., is a principal of Taylor Engineering in Alameda, Calif. He is a
member of SSPC 90.1 and GPC 36.

https://www.ashrae.org/

ASHRAE Journal - December 2019

Table of Contents for the Digital Edition of ASHRAE Journal - December 2019