Cool running: hi-tech ideas pull plug on air conditioners that add to global warming
- Researchers in Singapore develop water-based cool and dry air system that does away with harmful chemical refrigerants
- Major brands race to offer hi-tech efficient offerings, while smart glass blocks out excessive sunlight to keep the temperature constant
If they’re not already switched on, air conditioners will soon be cranking up across the city. Hongkongers might be borderline addicted to cooling the indoor air temperature, but it’s an environmentally indulgent habit.
A report by Rocky Mountain Institute, a United States sustainability think tank, says comfort cooling represents one of the largest end-use risks to our climate, with the residential sector alone set to account for an increase in global temperatures of more than 0.5 degrees Celsius (32.9 degrees Fahrenheit) by 2100.
Under a business-as-usual growth trajectory, the number of room air conditioner units in service is estimated to increase from 1.2 billion units today to 4.5 billion units by 2050. Much of this rise comes from emerging economies, where the uptake is expected to be five times the current rate.
Out with the old, in with the new…
No one wants to swelter through a tropical summer in the city, but Ernest Chua, associate professor at the National University of Singapore, says the big problem is that today’s most popular air conditioners use a 117-year-old technology.
“This approach, invented by Willis Carrier in 1902, is very energy-intensive and environmentally harmful; something has to change,” he says.
Chua and his team at the department of mechanical engineering at the university’s faculty of engineering have developed a cleaner, greener, water-based system which produces cool and dry air without using a compressor or chemical refrigerants.
“This is a new starting point for the next generation of air-conditioners,” he says. “Our technology has immense potential to disrupt how air-conditioning has traditionally been provided.”
The government-funded research has produced two new technologies – a membrane dehumidifier which extracts water from ambient air, and a device that removes heat from the air through evaporation without increasing its moisture content, in much the same way that sweat cools our bodies.
Unlike vapour compression air-conditioners, which release hot air back into the environment, an air stream that is comparatively cooler than ambient temperature is discharged – negating the effect of micro-climate.
About 12 to 15 litres (420 to 505 fluid ounces) of potable drinking water can also be harvested after operating the air conditioning system for a day.
Two-year wait for refined prototype
Leading businesses have shown interest in the prototype, but Chua and the team have decided not to license their Intellectual property and are developing the concept under their newly established company, NUS Cool.
Chua believes industries with high cooling needs. such as data centres and power plants, will be among the early adopters. District cooling, which involves the cooling of clusters of buildings, rather than each one separately, is another opportunity to expand production.
[Today’s air-conditioning] approach, invented by Willis Carrier in 1902, is very energy-intensive and environmentally harmful; something has to change
The “untapped niche” of outdoor cooling, offers huge potential as outdoor areas of shopping malls, alfresco restaurants and high-end residential properties could all use ways to keep people comfortable in hot and humid climates, Chua says.
Having proved the concept with a prototype, the team are now looking to refine the system – notably, to reduce the size of the unit so it is suitable for home. A current domestic unit would be about 20 to 25 per cent bigger than a normal window split-system.
Chua says a NUS Cool outdoor cooling system may be on the market for testing in one to two years, with a four to five-year wait for indoor systems.
Smart Wi-fi-controlled device
Meanwhile, brands working to cut emissions of their air conditioners include Carrier, whose ductless, single-zone residential climate control system was released last year.
Carrier’s most efficient ductless air conditioner to date is rated at 42 SEER (seasonal energy efficiency ratio) on the US standard – where the higher the number, the less energy the system uses to do its job.
The system includes Wi-fi connection and an integrated relative humidity sensor so it can make automatic intelligent decisions for a more comfortable space. An occupancy sensor detects human movement to direct airflow or cut energy use in unoccupied spaces.
Awarding-winning technology
LG Electronics’ range of Dual Inverter window air conditioners provide 40 per cent more energy efficiency than its previous best-performing model, and earned the brand the 2018 ENERGY STAR Emerging Technology Award, a US award honouring new and promising energy-saving technologies.
LG says its new room air conditioners are among the first in the industry to use a refrigerant with lower global warming potential. Its R32 refrigerant has been approved by the US Environmental Protection Agency as an alternative to the use of ozone-depleting hydrofluorocarbons.
Equipped with LG SmartThinQ technology, its Wi-fi-enabled models can be remotely controlled by smartphone, or voice commands using Amazon Alexa and Google Assistant.
Interconnected efficiency
Daikin has released its Daikin One Ecosystem, which incorporates advanced Internet of Things (the network of physical devices, home appliances and other items embedded with electronics, sensors and software which enables them to connect and exchange data) technologies with energy efficiencies rated up to 18 SEER.
At its heart is the Daikin One+ smart thermostat, engineered to communicate seamlessly with all Daikin One ecosystem components, including Daikin Fit condensing units, Daikin One air cleaners, and communicating furnaces and evaporator coils.
Daikin's Pathfinder (air-cooled) and Magnitude (water-cooled) chillers are both available with advanced compressor technology to maximise efficiency. Magnitude chillers are up to 40 per cent more efficient than standard centrifugal chillers with oil-free, magnetic bearing compressor technology.
Heat-blocking glass coating
Innovation in passive ways to cool buildings, such as heat-blocking glass, also holds promise.
An ultra-thin window coating developed in Australia by researchers at Melbourne’s RMIT University is one example. The self-modifying coating – 1,000 times thinner than a human hair – works by automatically letting in more heat when it’s cold and blocking the sun’s rays when it’s hot.
We lose most of our energy in buildings through windows. This makes maintaining buildings at a certain temperature a very wasteful and unavoidable process
Madhu Bhaskaran, professor and lead investigator of the team, says this breakthrough opens the door to “smart glass” that will help meet future energy needs and create temperature-responsive buildings.
“We lose most of our energy in buildings through windows,” she says. “This makes maintaining buildings at a certain temperature a very wasteful and unavoidable process.
“Our technology will potentially cut the rising costs of air-conditioning and heating, as well as dramatically reduce the carbon footprint of buildings of all sizes.”
Solutions to the global energy crisis “do not come only from using renewables”, she says. “Smarter technology that eliminates energy waste is absolutely vital.”
US$30 million innovation quest
In a quest to find innovative, climate-friendly technologies for residential cooling, a US$30 million Global Cooling Prize was launched last November, with a deadline for applications of August 31.
Led by the Indian government, with the backing of Sir Richard Branson, co-founder of venture capital conglomerate Virgin Group, its aim is to encourage the development of technology that will have at least five times less impact on climate than current standard room air conditioning. Such an outcome could prevent the equivalent of up to 100 gigatons of carbon dioxide emissions by 2050.
Prize money will be awarded over the course of the two-year competition, with 10 shortlisted competing technologies each receiving up to US$200,000 to support the design and development of their prototypes. The winning technology will be awarded at least US$1 million to support its incubation and early-stage commercialisation.