ASHRAE Journal - June 2020 - 49

ASHRAE - CELEBRATING 125 YEARS

environment, with the ability to test results before implementation in the ﬁeld, greatly reduces the risks associated
with incorporating new technologies and products.
The ﬁrst hydronic systems to be built with the modular process were simple pumping packages, mostly
comprised of pumps, electrical and a structural base.
As consulting engineers experienced the advantages of
these modular pumping systems, they began requesting systems with full mechanical, electrical and control
scopes. In 1981, the ﬁrst module with variable frequency
drives (VFD) for variable ﬂow pumping applications was
developed.
At the time, VFDs were large, expensive and unproven.
It was necessary to show energy savings associated with
variable ﬂow systems. The factory build and test setting
of modular manufacturing allowed for the development
of wire-to-water efﬁciency to analyze life-cycle cost and
show the relationship between system ﬂow and pressure
to energy use. The ability to generate a report with hard
data helped propel the use of VFDs in the industry so
more efﬁcient systems could be developed.
In 1995, variable primary pumping was introduced to
the industry. Mainly applied to chilled water systems, it
varies the evaporator ﬂow through the chiller. This was
a major advancement in chilled water pumping. Prior
to variable primary pumping, variable ﬂow through
chillers was risky because chiller controls were not
as advanced as today's digital controllers, and pump
control had not been reﬁned to adequately supply the
correct minimum ﬂow to the chiller. Variable primary
pumping solved this issue by using high-speed digital
control, minimum ﬂow bypass control and measurement of minimum ﬂow through the chiller.
Even with these signiﬁcant advancements, it was difﬁcult for project owners to fully appreciate all the beneﬁts
modular could offer. Pump packages are just a small part
of the mechanical system, so it was hard to break out the
cost of that small piece in the overall job estimate with
multiple contractors still crossing trades on the same project. A bigger piece of the mechanical room needed to be
modular to demonstrate the true value and advantages.
That happened in 1996 with the development of the
industry's ﬁrst modular chiller plant. The consulting
engineer for a variable primary pumping system asked
if the project's chillers could be integrated with the
system to create a fully enclosed plant installed outside
the facility. The answer was "Yes!" and modular utility

options have continued to expand.
Today, modular systems are advancing with developments in cogeneration, indirect evaporative cooling and
advanced algorithms for variable ﬂow control. With a
focus on research and development that isn't possible
in the ﬁeld, modular manufacturers are able to bring
innovations to the market to meet growing demands and
provide customers with efﬁcient and advanced utility
solutions.

Future is Modular
With increasing energy and environmental regulations, large national and multinational companies are
looking for ways to integrate, standardize and optimize
operations across multiple locales. The consistency and
stability of factory assembly allows for the standardization of procedures and monitoring of quality control.
The interconnectedness of customers, designers,
engineers, equipment suppliers and assemblers in the
modular process has made it conducive to developing
and implementing innovations in our ﬁeld. It provides
an opportunity to incorporate the newest technology
and tools like building information modeling (BIM),
3D printing and automation within the manufacturing
process.
Modular, off-site construction has also laid the framework to optimize a shrinking labor force and maximize
productivity. More customers are seeking out modular,
modular manufacturers are growing, and 25% of ﬁrms
in the 2018 AGC Workforce Survey2,3 reported adopting
or increasing the use of methods like off-site fabrication
to deal with labor shortages.
In this way, a centuries-old concept with decades of
success in the HVAC&R Industry is a tool of our future.

References

1. Earthtechling. 2014. "A 'Mod' History-ModCular Construction
Makes a Mark." https://tinyurl.com/y7y3dbja.
2. AGC. 2018. "2018 Workforce Survey Results." Associated
General Contractors of America. https://tinyurl.com/ya9havyz.
3. AGC. 2018. "Worker Shortage Survey Analysis." Associated
General Contractors of America. https://tinyurl.com/yd7w3vhp.

Bibliography
FMI Corporation. 2019. "2019 FMI Overview."
https://tinyurl.com/ya8ddory.
Modular Building Institute. 2015. Introduction
to Commercial Modular Construction. Charlottesville,
Va.:Modular Building Institute.
J U N E 2020

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ASHRAE Journal - June 2020

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