New advances in air conditioning technology have improved the efficiency of machines by as much as 90 percent, paving the way for significant energy use reductions in hot countries.
The research, which has been conducted at the US National Renewable Energy Laboratory, relies on the use of membranes, evaporative cooling and desiccants. None of these processes are new, but the researchers were able to combine them in a way that delivers far greater efficiency savings than previous attempts.
Traditional evaporative cooling air conditioning machines work by exploiting the physical property of air being cooled by water evaporating. The same principle is the reason why humans sweat, and why it's always cold when you get out of a pool -- the evaporating liquid cools you down
However, these systems only work well in dry climates, because they rely on the air not being already too full (saturated) with water vapour. Cooled air out of an air conditioning unit is also more humid than normal, which can cause problems in moisture-sensitive environments, like museums and art galleries.
The new technology, which is called DEVap, uses liquid desiccants (like the packets of silica gel that come with a pair of new shoes) to take humidity out of the cool air, lowering the resistance to evaporation that the air has when it cycles back into the machine, and therefore reducing the amount of energy it takes to get the water to evaporate, cooling the air again.
Thanks to the use of those desiccants, it also doesn't need to use refrigerants like CFCs and HCFCs, which are commonly used in residential air conditioning units and are 2,000 times more harmful than carbon dioxide as a greenhouse gas.
Right now, about 5 percent of all energy used in the US is just keeping buildings cool, so reducing that by 90 percent to 0.5 percent would be a massive help to US attempts to cut greenhouse gas emissions and energy consumption. It could also make the technology more attractive in cooler, more humid climates such as Britain.
The technology has been patented, but the lab plans to spend another couple of years improving the efficiency of the process further before it's licensed to industry, so don't get too excited yet. Still, this technology could prove a useful stepping stone towards further efficiency reductions in the future.