Daikin and Gree have been named as joint winners of the Global Cooling Prize, the international innovation competition to develop super-efficient and climate-friendly residential cooling solutions.
Participants had to develop a residential cooling technology with at least five times less climate impact than standard room air conditioning units and an installed cost not more than twice that of the baseline AC unit when manufactured at a scale of 100,000 units per year.
There were eight finalists but it was Daikin and Gree’s developments based on traditional vapour compression systems that won the day.
Daikin with partner Nikken Sekkei, one of the leading Japanese architecture and engineering design companies, proposed a system to ensure consistent room temperature and humidity using two specially adapted indoor units running on the low GWP refrigerant R1234ze(E).
The system also measures the outdoor temperature and automatically sprays water under high ambient temperature conditions, to lower the temperature of the air that the outdoor unit takes in.
Chinese manufacturer Gree Electric Appliances, partnering with Tsinghua University, proposed a hybrid solution using vapour compression refrigeration, direct evaporative cooling, and ventilation, automatically switching between modes or operating the three modes in parallel depending on the outside weather conditions.
It employs a new design of compressor using low GWP refrigerant R152a and improved evaporator and condenser systems to more effectively cool and dehumidify the air. The solution also included a small solar PV panel integrated into the outdoor unit.
R152a is an A2 flammable refrigerant with a GWP of just 124
The performance of all the prototypes were compared against the baseline unit – a fixed-speed, mini-split type RAC unit with an ISEER rating of 3.5W/W that used R22 refrigerant.
In 2019, the eight finalists were awarded $200,000 each to develop their prototypes. The two winners will now share the prize purse of $1million.
The Global Cooling Prize was launched by a global coalition led by the Department of Science and Technology, Government of India, leading global research body the Rocky Mountain Institute (RMI) and Mission Innovation, a global initiative of 24 countries and the European Union to accelerate global clean energy innovation.