Page 26 - Climate Control News May 2022

Indoor Air Quality
Sustainable cooling options for a net zero future
FANS HAVE AN important role to play in Aus- tralia’s net zero plans.
A University of Sydney led study has found us- ing indoor fans more often allows people to re- duce their air conditioner use without changing how hot they feel, paving a way for reducing fu- ture energy use and greenhouse gas emissions.
The study found electric fans are an effective and sustainable choice to circulate air indoors, without sacrificing comfort.
By using indoor fans, indoor temperature lev- els can increase by 3 to 4 ˚C more until it be- comes uncomfortable (the main reason why we reach for the air conditioner during hot weather) compared with air conditioner use alone.
An additional cost-benefit analysis in the pa- per on the environmental impact found the total benefit of using fans to reduce overall air condi- tioner use from a greenhouse emissions perspec- tive surpassed even the switch from incandes- cent light bulbs to LEDs.
Modelling led by the University of Sydney, found that just by slightly increasing indoor air movement by using indoor fans can reduce elec- tricity consumption and the associated cost of cooling indoor spaces with air conditioners throughout a typical Australian year by approxi- mately 70 percent.
Despite warmer indoor conditions because of less air conditioner use, the study found using fans still maintained the same comfort levels as lower indoor temperatures with regular air con- ditioner use.
The research was conducted by an interna- tional team of experts from the University of Sydney alongside Monash University, University of Newcastle and Radboud University medical centre, based in the Netherlands.
The work showcases how making the switch to widespread indoor fan use can potentially reduce energy demand and greenhouse gas emissions.
The key lies in the fundamental way electric fans operate to cool the human body compared to air conditioners.
“ELECTRIC FANS GENERATE HIGHER AIR SPEEDS ACROSS THE SKIN SURFACE TO REDUCE HEAT.
Electric fans generate higher air speeds across the skin surface to achieve a higher heat loss de- spite warmer temperatures, whilst air condition- ers by themselves lower temperatures with little air movement, according to Professor Ollie Jay.
“Through their sole purpose of lowering air temperatures, air conditioners feed a cycle of high electricity consumption.
“This is often delivered by fossil fuel power sta- tions that in turn contribute to further increases in emissions,” he said.
“The latest IPCC Sixth Assessment Report on Mitigation of Climate Change emphasises the need for adoption of low-emission lifestyles, in- cluding cooling choices for thermal comfort,”
The researchers compared the energy use and associated greenhouse gas emissions by modelling five scenarios with different combi- nations of fan and air conditioner use. This in- cluded situations with fans operating at differ- ent speed settings.
After logging data on the impact of the fans on human comfort levels before they begin to feel discomfort, the number of hours above the ther- mal comfort limit were calculated to determine air conditioner usage, and associated energy use and greenhouse gas emissions.
Professor Manfred Lenzen of the School of Physics, said to carry out this calculation the team needed to process hourly temperature data for an entire year, for the entire continent on a 150,000-cell raster grid.
“We were able to do this using supercomput- ers,” he said.
They found that operating fans with air speeds of 1·2 m/s with occasional air conditioner use, compared with air conditioners alone, resulted in a 76 per cent reduction in energy use (from 5592 GWh to 1344 GWh) and associated green- house gas emissions (5091 kilotonnes to 1208 kilotonnes).
“We know that curbing greenhouse gas emis- sions is the only way we will limit future global warming,” he said.
Fans suit
a low emission lifestyle.
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