Choose fans more and A/C less
We often turn to air conditioners during hot weather to cope
with the heat, but a study has 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 findings published in The
Lancet Planetary Health was conducted by an international team
of experts from the University of Sydney alongside Monash University,
University of Newcastle and Radboud University medical center, 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.
Our study confirms that low-cost solutions such as fans have the
potential to contribute emission reductions for meeting the goals of the Paris
Agreement.
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.
“Through their sole purpose of lowering air temperatures, air
conditioners feed a cycle of high electricity consumption - often delivered by
fossil fuel power stations that in turn contribute to further increases in
emissions,” said co-senior author Professor Ollie Jay, Director of the Heat and Health Research Incubator in the
Faculty of Medicine and Health.
“The latest IPCC Sixth Assessment Report on
Mitigation of Climate Change emphasises the need for adoption of
low-emission lifestyles, including cooling choices for thermal comfort,”
“Our study confirms that low-cost solutions such as fans have
the potential to contribute emission reductions for meeting the goals of the
Paris Agreement,” said lead author Dr Arunima Malik, Senior Lecturer in
Sustainability at the School of Physics and Business School.
Optimal conditions for sustainability and 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.
“To carry out this calculation we 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,” said co-senior
author Professor Manfred Lenzen of the School of
Physics.
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 percent 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,” says Professor Jay.
“By increasing indoor air movement with fans, you can feel the
same at a higher temperature as you will do at a lower temperature using an air
conditioning unit. This is a really easy thing that most people can do now to
help reduce the prodigious emissions associated with cooling homes and indoor
spaces in Australia.”