AIRCONDITIONING: Growing uptake of residential airconditioning is set to exacerbate the warming on the planet, according to research led by the Rocky Mountain Institute.

It is a horrible irony, as Iain Campbell, RMI Senior fellow, explains to The Fifth Estate.

The combination of rising heat, growing population, urbanisation and rising incomes in developing nations in hot and tropical regions is set to increase demand for cooling to the point it will be adding half a degree to average global temperatures by 2100 due to its energy use.

Currently, there are around 1.2 billion residential airconditioning units operating worldwide, a number that is exponentially increasing, he says.

One of the problems is the energy efficiency of AC is only increasing incrementally, as manufacturers tinker with existing technologies in minor ways.

The market also tends to initially opt into cooling by choosing the cheapest available units.

It is also a sector where competition is low, with about 35 per cent of units sold world wide coming from just two manufacturers.

Research and development among manufacturers is minimal, with the sector far outstripped by lighting and solar PV in terms of relative spend on R&D.

In combination, all of these factors have led to what Campbell terms “market failure” in the sector.

The technology is also “ubiquitous”.

AC has a “pretty incredible impact in relation to energy systems and demand,” Campbell says.

AC is on track to become over 10 per cent of global electricity use by 2050

According to the International Energy Agency, residential ACs will account for over two-thirds of cooling electricity demand and over 10 per cent of global electricity use by 2050.

The result is a vicious cycle – where global warming creates more demand for cooling, which then contributes to carbon emissions and more warming, leading to more demand for cooling…and so on.

In partnership with the Government of India, Germany’s energy agency, not-for-profits, universities and industry associations including AIRAH, ASHRAE and ISHRAE, RMI is leading the search for new approaches that can change the game for AC’s energy-efficiency and climate change impacts.

The Global Cooling Prize is looking for technologies that can deliver a “5X” gain – dramatically more energy-efficient, minimised use of water, no ozone-depleting or global-warming refrigerants and economical to purchase for the entry level market.

The goal is to find a pathway for cooling that can “meet the social need” it satisfies to ensure comfort, protect human health, maintain productivity and keep the economic wheels turning even during extreme heat.

Campbell says it is a very broad challenge, with “a lot of variables” that need to be assessed to optimise solutions.

He points out that the approach to residential cooling differs between new construction and retrofits of the technology to existing dwellings. It also varies depending on climate zone, dwelling typology and expected use.

We need to cool people, not buildings

The big levers for new construction are design and the build process, he says.

The first step is to understand that “people get hot, not buildings. We need to cool people.”

So the goal is to look at how to most efficiently serve cooling loads and how to optimise buildings and equipment so they meet those cooling loads efficiently.

Building codes that ensure dwellings are built to a high standard of performance are an obvious move when thinking about reducing loads.

“The cheapest time is when you first build, because you are dealing with incremental costs,” Campbell says.

For example, triple glazing adds only a fraction to the cost of a dwelling but can reduce the energy required for heating and cooling by 30 to 40 per cent.

But there is a “lot of dysfunction” in the market because “the builder doesn’t pay the energy bill”

Outcome-based and performance-based codes are important as a way of addressing this. Campbell suggests an outcome or performance-based rating for residential could be applied at the point of major events such as sale or refurbishment.

But while policy changes around codes and dwelling performance would be beneficial, the problem remains of how to keep everyone cool without cooking the planet.

Policy would help but technology and innovation also critical

Campbell says one of the exciting things about the cooling space and the early expressions of interest coming in for the Global Cooling Prize is the diversity of new technologies coming to light.

They go far beyond just swapping the refrigerant from synthetic to natural or tinkering with the set points or fan drives.

One of the technologies Campbell mentions is Thermoelectric cooling, which uses semi-conductor chips for the heat exchange. It’s already being used by NASA for spacecraft cooling – and as spacecraft are off-grid habitats, energy-efficiency is high on the agenda.

Campbell says we have already seen the power of scaling semi-conductors with computers and solar PV. Another positive of the approach is there are no moving parts or fans, and no cooling fluids involved.

Innovations including one that turns heat into a wavelength to be sent into space show promise

Another innovation is coming out of the materials science space, where elastocaloric cooling is being investigated. It involves stressing certain alloys which then generate heat or cold and is based on similar principles to how muscles work.

Campbell says the early tests are showing “staggering” energy efficiency, with a Coefficient of Performance potentially as high as 30, compared to existing the COP of three to 17 available with existing technologies.

Another innovation is “magnetocaloric” approaches that uses magnetic fields, and there is also significant research and development in the coatings space, including “deep space radiative cooling” materials that can turn heat into a wavelength that can be passed through the atmosphere and out into deep space, turning the wider galaxy and beyond into a heat sink.

Campbell says it is also possible to look at combining some of these emerging technologies and existing to “supercharge the effect”, for example, using one of the new-age coatings on the heat rejection system of a business-as-usual AC unit.

He sees the potential for “transformation” in the residential AC space, both through some of the new technologies on their own, and in conjunction with other technologies.

The goal is to “build a huge coalition to get the power of amplification”, he says.

In Australia, Campbell says adoption and scaling of a 5X solution would see energy consumption from residential AC reduce by 20 terrawatt hours by 2050 – equivalent 21 avoided 235 megawatt gas power stations and with a saving of $15.4 on investment in the grid and generation.

  • See full details of the Global Cooling Prize and how to enter here

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  1. The Global Cooling Prize should expand its technical requirements to be more open. New solutions like HyperBorean stands ready to grow into a viable solution.

  2. Hi Mike – good thoughts, particularly about the transition to a low carbon economy being part of changing the game.

    I will ‘fess up though to being based in that exact region you name [Wagga/Albury] as being one that experiences freezing cold [overnight below zero is normal in winter], and boiling heat [up to 46 and above some days in January just past]. So the article WAS written by someone who fully recognises just how essential some form of heating/cooling is to stay healthy, functional and comfortable for quite a significant proportion of the year!

    Pretty exciting to see some of the tech out there too.

  3. Accepting the view that there will be a transition, beyond the Carnot cycle the inertia of thomas midgley family refrigerant stranglehold in australia can be halted tomorrow- the technology is there but the political and transnational business of royalty flow is not. In an limited documentation trial in Darwin, a split AC employing R410A was recharged with an australian manufactured HC refrigerant, no other mods, with a reduction of 40% in input energy, and a recordable inprovement in cooling[that is, even in higher ambient condensing, reduced vent temp].
    In respect of building design, the diurnal values of thermal mass external walls for passive acquisition of external energy as heat, the thermal capacity, R & E values are well documented. But the old lazy construction methods go on. Insulate external walls internally with at least R2.5 PIR foam pre bonded to internal finish sheet[plaster sheet by default], ceiling sheet r3.5 pr e bonded. Our estimate is that capitalisation increase, off set by 50% reduction in reverse cycle AC requiremnent and prefinishing of internal walls, is at best marginal. Simple ROI we estimate at under 4 years, in the macro lifecycle of the building of 100 years.
    Happy to expand on this thread with more technical information.

  4. thanks for the interesting article to get my brain thinking -but sadly this seems to hold onto the premise that AC units will continue to run on coal power -but a complete transition of the grid to low carbon renewables will see the AC (heat pump that efficiently both heats and cools)become the essential toole to have in the house in times of heat waves/freezing days -I proudly have an AC unit that sits most of the year “turned off” but it sits waiting for when it is essential to do its very efficient heating /cooling-we need to be thinking of a LOW CARBON ECONOMY-yes I just used those words -a LOW CARBON ECONOMY -thats where innovation needs to focus then all else will follow -oh and I wish that only people living in the inland of heat /cool extremes like Wagga /Albury /Cootamundra or(and Penrith) anywhere west of the Blue Mts should write these articles because they fry in summer and freeze in winter -so AC units are important -just change their energy source and add in many many thousands upon thousands of trees in the suburbs !!!! -now thats “KOOL” and innovative. Thanks again for an interestinfg article