ASHRAE Journal - December 2019 - 28

TECHNICAL FEATURE

Planning for Failure

End-of-Life Strategies
For HVAC Systems
BY GRANT WHEELER, ASSOCIATE MEMBER ASHRAE; MICHAEL DERU, PH.D., MEMBER ASHRAE

The use of mechanical air-conditioning systems is
expanding rapidly around the world. An estimated 700
million air conditioners will be operating in the world
by 2030.1 This is great news for the HVAC industry, but
this growing demand for air conditioning has enormous
environmental and economic impacts. In fact, management of refrigerants was put forth in a recent book
as the number one strategy to reduce climate change
impact.1 In the United States, there are several existing
and pending regulations for refrigerant management,
and the range and complexity of these regulations make
it difficult for engineers, contractors, and building owners to keep up with all the requirements, and they introduce confusion and uncertainty in the market.
Most of the economic and environmental burdens
from HVAC systems occur during the use phase, but
what happens at the end of life can also have a significant impact if not managed properly. When an
air-conditioning system fails, owners often want the
fastest and lowest first-cost solution. Decisions made
at the time of replacement have long-term financial
and performance effects, and the quick fix approach
can result in an environmental and economic disaster.
Owners of HVAC equipment have a tremendous opportunity and responsibility to find optimal solutions with
the best economic performance and smallest environmental footprint.

As a means of perspective, the amount of material for
residential and commercial central air conditioners
and air source heat pumps in the United States is shown
in Figure 1 based on Air-Conditioning, Heating, and
Refrigeration Institute 2014 unit shipment data.2 The
weight distributions are estimated, assuming similar
material distributions as a 3 ton (10.5 kW) residential
split system and a 20 ton (70 kW) rooftop unit (RTU).
These numbers do not account for portable and window
air-conditioning units, dehumidifiers, water source
heat pumps, or chillers. It should first be noted that the
values presented in Figure 1 are only an estimate meant
to provide context when discussing the sheer amount
of material required for HVAC equipment. Residential
systems alone have several material categories in the
hundreds of millions of pounds that are needed for
manufacturing annually. Were the roughly 25,400 metric tons of refrigerant to be released to the atmosphere
that would be equivalent to 53 million metric tons of
carbon dioxide (lb CO2e) assuming R-410A with a global
warming potential (GWP) of 2088.
The impacts of disposing of this material are clearly
large, but the potential for reusing and recycling air
conditioning systems is also great. Figure 1 shows that
80% to 88% of air conditioners are recyclable greatly
reducing the impact of appliances when best practices
are followed. This article looks at the impact of the

Grant Wheeler works in the Building Energy Science Group at the National Renewable Energy Laboratory (NREL), Golden, Colo. Michael Deru, Ph.D., is a senior research engineer in
the Building Energy Science Group at NREL and managed the Advanced RTU Campaign for the U.S. Department of Energy.
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ASHRAE Journal - December 2019

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