ASHRAE Journal - May 2020 - 66

COLUMN ENGINEER'S NOTEBOOK

replacing HVAC equipment at the end of its typical
operational life or during tenant installations. Thus, we
are brought back to the question of "reuse" and "recycle"
for the HVAC industry. To understand the context for the
HVAC industry, it is useful to have a quick overview of
circular economy principles.

FIGURE 3 A comparison of linear, recycling and circular economy principles.
Source: Stopwaste & Arup, p.1.9

Take

Make

Use

Dispose

Linear
Economy

Recycle

Standing up to Entropy
Recycling
Economy

Circular economy thinking adopts the notion that economic growth can be decoupled from finite resource
consumption by changing the way we envision the life of
a material asset to include its reuse or reincarnation. The
Recycle
Ellen MacArthur Foundation (EMF) is currently among
Repair
the chief proponents of this view, arguing that in a world
Circular
Reuse
Economy
of limited resources (Figure 3), we must learn to move from
a linear economy of "take, make, use, dispose" to a circular economy of renewable resource, where we "design out
waste and pollution, keep products and materials in use,
Take
Make
Use
Dispose
10
and regenerate natural systems."
In the built environment, this idea of circularity has
FIGURE 4 Cradle to Cradle concepts as articulated by McDonough & Braungart.11
Source: Image 2 from Arup.13
been championed for over two decades by architect
William McDonough, who articulated his seminal
Cradle-to-Cradle design philosophy11 (Figure 4) to argue
that buildings, like nature, could be built as if "waste
equals food" (p. 192) and run on "diverse and renewing
energy flows" (p. 132).
Even before that Ray Anderson, CEO of Interface,
Waste is Food
Use of Renewable Energy
Celebrate Diversity
decided in 1995 that his carpet
company would commit to the goal
FIGURE 5 Circular economy systems diagram as adopted from EMF.10 Source: Figure 2 from Arup.6
of using no virgin materials in its
products by 2020. This vision not
Renewables
Finite Materials
only changed the manufacturing
Regenerate Substitute Visualize Restore
process but also spawned a takeMaterials
Renewables Flow Management
Stock Management
back program for the company's
Technical Cycles
Biological Cycles
own products and eventually for
Farming/
12
those of their competitors. This is
Parts Manufacturer
Collection1
a classic example of the "refurbish/
Biochemical/
Product Manufacturer
Feedstock
Recycle
Regeneration Biosphere
remanufacture" and "recycle" cycles
as noted on the right-hand side of
Service Provider
Refurbish
Share
Remanufacture
the Ellen MacArthur Foundation's
Reuse/Redistribute
circular economy systems diagram
Biogas
Cascades
Maintain/Prolong
in Figure 5.
Consumer
User
Anaerobic
Digestion

Riding the Loop-de-Loop

Extraction of
Biochemical Feedstock

At the top of Figure 5 is the input
of material resources and energy.
The hope is that renewable energy
66

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