• The study compared fans and air conditioners
    The study compared fans and air conditioners

Fans have an important role to play in Australia’s net zero plans.

A University of Sydney led study has found using indoor fans more often allows people to reduce their air conditioner use without changing how hot they feel, paving a way for reducing future 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 levels can increase by 3 to 4 ˚C more until it became 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 paper on the environmental impact found the total benefit of using fans to reduce overall air conditioner use from a greenhouse emissions perspective surpassed even the switch from incandescent 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 electricity consumption and the associated cost of cooling indoor spaces with air conditioners throughout a typical Australian year by approximately 70 percent.

Despite warmer indoor conditions because of less air conditioner use,  the study found using fans still maintained the same comfort levels as a lower indoor temperatures with regular air conditioner use.

The research was conducted  by an international 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 achieve a higher heat loss despite warmer temperatures, whilst air conditioners 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 stations that in turn contribute to further increases in emissions,” he said.

“The latesIPCC Sixth Assessment Report on Mitigation of Climate Change emphasises the need for adoption of low-emission lifestyles, including cooling choices for thermal comfort,”

The researchers compared the energy use and associated greenhouse gas emissions by modelling five scenarios with different combinations of fan and air conditioner use. This included situations with fans operating at different 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 thermal 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 supercomputers,” 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 greenhouse gas emissions (5091 kilotonnes to 1208 kilotonnes).

“We know that curbing greenhouse gas emissions is the only way we will limit future global warming,” he said.

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