Space cooling eats up 10% of global electricity use, and by 2050 total energy consumed could triple as ownership takes off in developing countries. It’s why the Global Cooling Prize was launched to find AC designs that will have an 80% lower climate impact, explains John Matson at RMI. The two main design goals were to reduce electricity demand, and use refrigerants with lower global warming potential (GWP) than traditional refrigerant gases. The two winners – Daikin (from India, one of the world’s leading AC manufacturers) in partnership with Nikken Sekkei (from Japan, specialising in architecture and design), and Gree (from China, the world’s largest residential AC manufacturer) in partnership with Tsinghua University – both met the challenge. If the winning technologies could be scaled, they could mitigate more than 0.5°C of warming by the end of the century, says Matson. But rapid scaling up will need the right policies too, not just manufacturing muscle. Today’s performance standards set and gradually raise the minimum efficiency of ACs to improve performance. They should instead be taking the efficiency baseline from the best-performing products. Secondly, testing standards only assess a limited number of technology parameters. Instead, a wide-ranging tech-agnostic set of standards is needed to recognise and reward the leading innovations, and open the door to new and better solutions.
The world leaders of the Group of Seven, better known as G7, released a long communique following their recent meeting in Cornwall, detailing their plans to address the COVID-19 pandemic and “build back better.” In a departure from the previous G7 meeting in 2019, which ended with a briefer list of agreements, this year’s G7 summit yielded more alignment, particularly in the areas of climate change and the energy transition.
Although the final list did not include all the measures needed to keep global temperature rise to 1.5°C, the environmental and climate agreements did include some overlooked and significant measures to prioritise efficiency. These include doubling the efficiency of cooling systems sold worldwide by 2030.
Space cooling: 10% of global electricity use… and rising
Developing much more efficient cooling technologies will be critical to keeping 1.5°C within reach. Appliances for space cooling already account for about 10 percent of global electricity use, according to the International Energy Agency (IEA). And without efficiency improvements, the energy consumed for cooling could more than triple by 2050. Inefficient cooling systems also contribute to large peaks in electricity demand, which can overwhelm electric grids during hot spells.
The challenge of increasing the average efficiency of cooling systems is at least twofold, driven by both technological and policy changes. But the recent Global Cooling Prize has demonstrated that superefficient ACs are technologically feasible, and policy changes can now catalyse the commercialisation and adoption of more efficient units.
Between now and 2050, an estimated 3.3 billion room air-conditioning units will be installed globally as heat waves become more common, populations grow, and urbanisation increases. As of 2016, the IEA estimated, more than half of all air conditioners in service were in China and the United States. But over the coming decades, air conditioning use is expected to increase rapidly countries such as India and Indonesia, where residential AC is relatively rare today.
Cooling is not just a matter of comfort and convenience. More than a billion people today are at high risk to their health and safety due to lack of access to cooling, according to a report from Sustainable Energy for All. And those risks will increase as climate change drives greater temperature extremes.
Superefficient ACs: 80% lower climate impact
RMI launched the Global Cooling Prize in 2018 with Mission Innovation and the Department of Science and Technology of the Government of India. The $1 million Prize set out an ambitious challenge for innovators to develop affordable cooling solutions with at least 80 percent lower climate impacts than a baseline unit.
In April 2021, the Prize was awarded to two teams—both representing large industry players—that successfully developed and tested prototype units that met the Prize criteria. Both winning teams met the threshold of 80 percent lower climate impact by reducing electricity demand and using refrigerants with lower global warming potential (GWP) than traditional refrigerant gases.
The Global Cooling Prize team estimated that, if the winning technologies could be scaled, they would mitigate more than 0.5°C of warming by the end of the century.
Accelerating scale-up: two main policy levers
The Global Cooling Prize proved that superefficient ACs running on low-GWP refrigerants are technologically feasible today. But policy changes would help accelerate the commercialisation and adoption of efficient cooling units. As noted in a previous blog post, policymakers have two main levers to drive AC efficiency advancements: improving performance-rating systems for cooling products and creating testing standards that are technology-agnostic.
First, performance standards should recognise what is already possible and encourage manufacturers to continually push for more efficient products that consume less energy and cost less to operate. Today’s performance standards tend to focus on minimum acceptable efficiency levels. These ratings systems gradually raise the floor of efficiency to improve the performance of the laggards but do little to recognize or encourage the adoption of the best performers, which often surpass the highest defined efficiency level altogether. Japan, in contrast, has done just the opposite—identifying the best-performing products and setting the efficiency baseline based on those performance levels.
Second, the winners and finalists in the Global Cooling Prize showed that a variety of technologies can be incorporated into efficient cooling solutions. Some of the finalist prototypes incorporated solar photovoltaics, evaporative cooling, enhanced dehumidification capabilities, and other approaches. However, testing standards that assess an air conditioner’s capacity and efficiency are generally not designed with this variety of solutions in mind. Technology-agnostic testing standards would allow manufacturers to innovate more freely and combine multiple technologies to provide efficient and affordable cooling.
With the G7 summit concluded and the 26th UN Climate Change Conference of the Parties (COP26) coming up in the fall, we look forward to additional conversations and commitments that advance the goal of sustainable cooling. Specifically, a “Race to Zero” Breakthrough challenge aims to enlist AC manufacturers representing 20 percent of the market by COP26. The goal of the challenge is for those manufacturers to bring AC units to market by 2025 that have 80 percent lower climate impact.
If manufacturers and policymakers can take these superefficient ACs from prototype to production, they can significantly limit the climate impact of cooling as billions of new air conditioners hit the market over the coming decades. For a rapidly warming world, this is a matter of survival.
John Matson is a Writer/Editor at Rocky Mountain Institute (RMI).
This article was first published on RMI.org and has been reprinted with permission
Roger Arnold says
Efficiency for a cooling system is tricky to pin down. It’s easy enough, with a conventional AC unit, to measure the volume and temperature of air coming out of the unit, and the power consumed. From that one can compute a number for cooling capacity vs. power consumption. If one wants to use that number as the basis for an efficiency rating, fine. But what does it mean, when appropriate building design can passively deliver all the cooling necessary for comfort, even in hot climates? No power needed at all, beyond opening and closing windows. Is that infinite efficiency?
I’m thinking, in part, of net zero “Earthship” homes. Most of the ones I know of in the US have been built in the high desert environments of northern New Mexico and southern Colorado. Nights get cool, even after hot summer days, and the thermal mass of thick earthen walls plays a large role in maintaining comfortable temperatures. But that’s only one class of passively cooled homes.
In hot, humid environments, it may not cool off much at night. Thermal mass won’t help much, but it’s still possible to achieve comfortable indoor temperatures with minimal expenditure of power. The trick is to deploy good thermal insulation along with an appropriately designed desiccant cooling system. A desiccant cooling system absorbs moisture from ambient air, allowing it to be evaporatively cooled. An external heat source of some sort is needed to regenerate the desiccant. It can be a relatively low grade heat source from a solar thermal heater, waste heat from an oven, or heat supplied by a district heating system. It could also be heat supplied by a heat pump, and there are units sold commercially that do just that. However that design defeats the goal of “minimal expenditure of power”. It’s not clear to me what advantages a desiccant cooling system driven by a heat pump offers over a conventional heat pump driven AC system.