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Circular Economy Reflection – Should Old Air Conditioners be Rebuilt?

The circular economy is one with the idea that when a product fails or is replaced, it can be broken down into its components, and then these components can be processed and stripped back to raw materials, and made into new products.

Recycling an air conditioner would involve taking it apart, separating all the different materials, such as copper, aluminium, plastic, steel, and then melting the metals for reuse and grinding up the plastic so they can also be reused.

Or, perhaps more likely, rather than being recycled in the same city it was discarded, the air con may be shipped off somewhere and stockpiled, eventually broken down, and then the broken-down components go into a pile waiting to be reused. Or perhaps it just ends up in landfill. Or rotting in the corner of a yard.

Reuse instead of recycling

But what if we looked at reusing as many of the components as possible instead of the traditional recycling approach?

I’m not exactly sure, but I believe most split system air conditioners will be taken out of service and scrapped for reasons such as not providing enough cooling (perhaps there is refrigerant leakage?), the controls have failed, its too noisy, its not energy efficient. Some components may have failed, or partially failed, and driven the replacement decision.

But many of the components could still be in reasonably good working order. Such as the housing, the fan on the indoor unit (at least the blades), possibly the coils.

Is it economic / viable to rebuild an old air conditioner? But not just to the point till its performance is similar to new, but to the point where its performance is as good as a high efficiency new air conditioner? And so that it can use a modern refrigerant, with a much lower global warming potential?

Old air conditioner - circular economy
Old air conditioner – circular economy

A circular economy exercise – what would be involved in reusing air conditioner components to make a more energy efficient air conditioner?

The efficiency of an air conditioner depends on just a few key factors:

  • The size of the condenser and evaporator coils relative to the cooling capacity of the unit. The bigger the coils, the better.
  • The efficiency of the compressor (and its motor) and the ability for its speed to be controlled
  • The efficiency and degree of control of the expansion valve
  • The efficiency of the indoor fan (and motor).
  • The control system

Could an old split system with say a 5kW cooling capacity, by reusing its coils, indoor and outdoor housing, possibly the indoor fan blades, be converted into a high efficiency unit with a 3.5 kW cooling capacity, replacing the compressor (with one suited to a lower GWP refrigerant), the expansion valve, the control system (eg the new controls could have demand response capability inbuilt) and sensors, the motor on the indoor fan?

Are coils made brittle or otherwise unsuited for reuse by some refrigerants?

Could a workshop with the right tools, and work teams with skills in cleaning, cutting and joining pipes, fitting, electronic controls and electrics, pressurising and testing refurbish a unit in short enough time to be able to be economically competitive? A practical expression of the circular economy.

Has there been enough standardisation in the manufacture of ACs for long enough that replacing a compressor, changing the valves, refitting a fan motor, replacing the controls isn’t that hard?

Could it be done economically in low volumes? How low?

Is it practical to believe relatively unskilled workers could be trained to do it?

The process would start by examining an old unit that has come in to determine what can be reused, pressurising the coils to see if they were fit for reuse, and sizing the new replacement components that would result in a high efficiency refurbished unit. Then a work crew would take it apart as much as needed to replace components. Coils could be flushed and cleaned.

Air conditioner coils - circular economy
Air conditioner coils – circular economy

And there is a growing number of old split systems rotting away around the world, but possibly many of them appear to have good bones. A few damaged fins doesn’t matter too much on a coil if its going to be over-sized in a new application.

Refurbishing has the following appeal:

  • Skills development/job creation
  • Reusing is more efficient than shipping to Asia, breaking apart, smelting the metals and grinding the plastics, then re-using.
  • For small pacific islands possibly reducing the trade imbalance a little
  • A feel good factor.

But there would be the following risks in this circular economy approach:

  • Marketing – units won’t look as good as a new unit, and will likely be bigger for the same capacity. Would probably need to be marketed as “Sustainably ugly” or something along those lines. Perhaps scope to employ an artist to decorate the refurbished units in a unique style? The aircon as a piece of art…
  • Managing waste from the refurbishment facility (eg chemicals used to clean out old coils, discarded old components).
  • Getting sufficient volume for it to be a viable business.
  • The HFC phase out to very low GWP refrigerants – existing split system coils wouldn’t be able to handle the pressure of CO2 as a refrigerant for example. So if it was a viable business, in 10 years time it may not be viable because of the challenges of using very low GWP refrigerants in older coils.

Is this viable? I originally posted this article on linked in, where a comment came back about using propane as a refrigerant, it doesn’t require the high pressures of CO2, and has a relatively low global warming potential.

I’ve travelled to several Pacific island countries in the last few months. One of these very small islands has around 1000 shipping containers full of stuff come in each year, and just 30 containers go out full. Another had a massive yard full of old cars and scrap metal near the port. Evidence of what is a linear economy, not a circular economy, bought into stark relief on small islands with limited land.

Discarded products - circular economy
Discarded cars and other products – circular economy

More broadly this reflection on old air conditioners raises the inconvenient truths associated with worn out equipment and the challenges associated with trying to minimize the environmental impact of end-of-life products.

For corporations serious about sustainability, what happens to products – even green products like solar panels and LED lights – at the end of their life, is an important part of sustainability planning and management.

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