The chart compares one typical Sydney building’s electricity profile from 7 and 8 January 2013 with 2 and 3 February 2011, the peak of last summer’s heatwave. Click on graphic to expand view.

11 January 2013 – We know the bush didn’t fare too well during the heatwave and bushfire outbreaks across the country this week, but how did city buildings fare?

Craig Roussac’s Green Buildings Alive building monitoring operation kept a close eye batch of 13 buildings in Sydney and the verdict was not bad at all.

On Tuesday when average national temperatures reached 40.33°C and in Sydney 41°C, energy consumption for the sample batch was 39 per cent higher than a typical day’s consumption,” the Green Buildings Alive website said in its blog post.

“That extra electricity consumption for those 13 buildings (280,000 square metres of office accommodation) is about equivalent to the average electricity consumption for four Sydney homes for a whole year,” the post said.

“Average savings were 14 per cent for the Sydney buildings being monitored, or 14 per cent better than might be expected for such a hot day.”

Roussac’s team puts it at least partly down to good building management.

“This is possible because building operators have been fine-tuning energy performance over the last year, as well as the relatively cooler temperatures experienced the night before and the low daytime humidity, which also helped.”

It was a different story with Sydney’s heatwave of February 2011.

“In the seven-day February 2011 heatwave 11 of the 20 Sydney buildings we analysed recorded their highest daily electricity consumption for the year, whereas yesterday (8 January 2013) saw none of the 13 buildings hit their highest consumption or yearly peak load.”

in this case it’s the constant heat that makes the difference.

“With consecutive hot days, and high overnight temperatures, heat is ‘stored’ in a building, so extreme electricity consumption is exacerbated. On these days, a building must not only remove the heat of the day, but also the built up heat that resides in its structure and furniture.”

Cooler overnight conditions mid week may have taken some pressure off building services, but the “efforts by the building’s operator also made significant savings.”

For one building being monitored the electricity performance was 26 per cent better than Buildings Alive’s weather-adjusted model indicated would have been a reasonable energy demand under the circumstances.