Building and Construction

A $300 million offer by a Chinese company to buy an Australian builder is withdrawn on the back of advice that Treasurer Josh Frydenberg and the Foreign Investment Review Board will declare the transaction a risk to national security and contrary to Australia's interest.

Analysts say there are high hopes for the long term viability of Sydney's construction industry with billions of dollars promised for projects including a $500 million 50 storey high-rise two blocks from Circular Quay.

The average house in Australia only rates about two out of 10 stars for energy efficiency, but with a smart retrofit the rating can be tripled, slashing power bills at the same time, the CSIRO says.