Canberra's long-running smoke haze has rendered evaporative air conditioners ineffective and led to a spike in ACT power demand, much of it from airconditioning systems.
Evaporative systems which draw air in from outside the house and push it through water-laden filter pads for cooling are cheaper to run than airconditioning but will also draw in other contaminants, such as smoke particles.
So when bushfire smoke haze fills the air outside on hot days, airconditioning experts say the best way to keep it out is to seal your house as well as possible and keep the airconditioning set at a tolerable temperature.
"The common mistake people make is when they first get home to a hot house is to set the temperature on their airconditioner as low as possible and crank the fan up full blast," Fredon airconditioning service manager Marcus Einfalt said.
"The better tactic is to set the temperature at 23 or 24 degrees C, then let the unit gradually catch up to the thermal load sitting inside the house.
"The unit will work at its maximum efficiency and not waste energy coolingbeyond what's necessary for a comfortable temperature."
The Fyshwick based specialist company which installs and services some of the most important airconditioning units in Canberra including high profile military, legal and education institutions, will have its technicians on standby over the Christmas-New Year period as temperatures climb into the high 30s and beyond.
Mr Einfalt said airconditioning was effective as a smoke filter, provided your house was well sealed against drafts and external air.
"The way split system airconditioning works in summer is that the condenser sits outside and manages the heat expulsion, while the head unit inside the house re-circulates and manages the airflow and temperature," he said.
"The condenser only manages external air so it has no capacity to draw smoke into your house."
He said that the arrival of inverters into domestic airconditioning had been a dramatic technology shift, allowing large units to ramp down and use little power when their load and capacity was not required.
"The extra capacity costs a little more at purchase time but you save that extra $500 or so in power bills over the medium to long term," he said.
"Also a smaller unit will need to run longer and harder to achieve the same result, which affects its operating life."
Canberra's power supplier Evo Energy reported that the peak electricity loads during both extreme temperature days last week, Thursday (December 19) and Saturday (December 21), were "well within our network capacity".
Peak network load on Thursday was 615 megawatts at 5.30pm. Although Saturday's temperature peaked at 41.1 degrees, a December record for the capital, peak network load fell because of the weekend's lower demand and hit 550 MW at 3.20pm.
Last summer, a new record system peak demand of 657 MW occurred at 5pm on Thursday, January 17 as the result of sustained heatwave conditions. Canberra's maximum summer temperature of 41.6 degrees was reached on January 16.
Conversely, during the 2019 winter, peak ACT electricity demand occurred on August 9 and was 614 MW.
Canberra's environment, planning and sustainable development directorate suggested that to save on power costs, people should only cool the rooms needed and to use pedestal fans and ceiling fans to circulate the air and add to the cooling effect.