Tradies and other workers exposed to the elements typically reduce productivity by 30 per cent on those days, while home owners pay more as they crank up their air conditioning.

The biggest chunk of the cost comes from the impact of heat stress which is most dangerous to babies, young children, the elderly and pregnant women.

Partly due to geographical differences, suburbs in Western Sydney are typically 6C to 10C hotter than coastal suburbs during heatwaves.

Sam Kernaghan, from the Committee for Sydney which commissioned the report, said heatwaves were making Sydney's west less liveable and more expensive.

“Every time the mercury reaches 35C, homes and businesses are burning money across Western Sydney," the committee's resilience director said.

"These costs are being paid by us - residents, businesses and taxpayers of Sydney and NSW."

The report's modelling suggests heat-related costs could jump five-fold to more than $6.8 billion by 2070 due to climate change.

That includes $150 in cooling, $330 in lost productivity and $716 in health costs per western Sydney resident.

"We know heat will constrain outdoor operations and maintenance, including utilities, construction and the logistics sectors," Mr Kernaghan said.

"Indirect costs include the cost of cascading impacts, such as melting road and runway surfaces, as well as the buckling of railways due to thermal expansion."

The economic cost of heatwaves should be embedded in NSW's next intergenerational report, due in 2026, the report recommends.

It also asks insurers and the NSW Reconstruction Authority to explore options to minimise heatwave risk to the economy, including insurance options to reduce the financial risk to business.

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