A new cooling technology co-developed by NUS researchers is being installed in commercial applications across Singapore.

The team from NUS Mechanical Engineering, working with industry collaborator Ecoline Solar, developed the next generation of hybrid solar-thermal air conditioners, to reduce energy consumption and carbon footprint associated with cooling buildings. Now, the novel technology is taking off, with clients including NCS Singtel, Starhub, and Highway International all installing the systems in their buildings recently. The technology has also provided cooling solutions to Singapore’s ‘vertical farms’, as well as several condominiums and hotels across the country.

The innovative air conditioners comprise an unconventional electrical compression machine that uses the heat from the sun and ambient surroundings to ease the electrical load of energy-guzzling compressors by up to 55 per cent.

“As the global temperature rises, fuelled by urbanisation and exacerbated by climate change, so does the global demand for fuel to run energy-hungry air conditioning. Today’s conventional air conditioners require high electrical energy, yet at the same time, they also produce a high volume of heat which is released into the environment, causing the creation of undesirable heat zones,” explained Associate Professor Ernest Chua Kian Jon from NUS Mechanical Engineering who led the team.

“The NUS and Ecoline innovative hybrid system leverages solar thermal technology to markedly reduce energy consumption and cut the volume of heat dissipated to the environment through our specially designed condensing unit,” he said.

How the system works

The jointly-developed solution utilises a solar thermal collector (i.e. heat collector) comprising vacuum tubes filled with a novel medium specially designed and engineered by the NUS team to absorb more solar energy and ambient heat.

The harnessed energy is then recycled to assist in the superheating of the refrigerant in the system, converting it from a low pressure, low temperature gas into a high pressure, high temperature gas. This reduces the system’s reliance on the compressor that pumps the refrigerant through the system and, in turn, reduces the system’s overall electricity consumption and the harmful greenhouse emissions released to the environment.

Lower bills and smaller carbon footprint

The team believes that solar thermal air conditioning technology is poised to help Singapore and the world improve the energy efficiency of buildings as it is potentially an effective way for businesses and households to reduce their operating cost and carbon footprint while becoming an integral part of the global warming solution.

Actual usage data showed that this hybrid system has consistently reduced energy usage to cut down utility bills by 30 to 55 per cent, depending on the pattern of usage.

Mr Colin Chia, Director of Ecoline Solar who led the collaboration project, said, “The hotter the sun and the warmer the surrounding environment, the more efficient our hybrid air conditioner system becomes. This is a game changer in the air conditioning industry. For consumers, this translates to greater savings in electricity consumption even when compared to the best conventional and inverter air conditioning systems in the market.”

This hybrid solar thermal air-conditioner is now available to consumers in Singapore. While it costs about 20 per cent more than an inverter air-conditioner, this cost difference is easily offset by the electrical cost savings in under two years. In the long run, this would be a more cost-effective cooling option.

The project was conferred the Prestigious Engineering Award by the Institute of Engineers Singapore and the ASEAN Outstanding Engineering Award by the ASEAN Federation of Engineering Organisations in 2019.

Next steps

This collaboration between the NUS team and Ecoline Solar demonstrates how research done in NUS’ laboratories can immediately impact applications and help industries to become more competitive and value add to their customers.

The two collaborators are now working to incorporate NUS’ patented membrane dehumidification technology to the thermal-based air conditioner to yield even higher energy savings.