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Heatwaves are cities’ number one danger, but the built environment can help

The three-day heatwave over large swathes of Australia has sharpened the focus on how our cities can cope with increasingly extreme climate conditions.  Commercial buildings are one area offering some hope for grid stabilisation, with technology at the forefront of work to keep temperatures – and energy use – down.

News of a three-day heatwave across much of Australia led to Sydney’s chief resilience officer Beck Dawson warning that decision-makers needed to have a serious discussion about how to deal with heat. 

“Our risk assessment for Sydney ranked extreme weather as the biggest potential shock, ahead of financial institution failure, infrastructure failure, disease pandemic, water crisis, digital network failure, cyber-attacks and terrorist attacks,” Ms Dawson said. 

“Within the extreme weather category, heat impacts contribute to more deaths than bushfires, floods and storms combined. We classify heat as Sydney’s silent killer. It sends more people to hospital than any other risk Sydney is threatened with yet doesn’t seem to command the level of public concern that is should.” 

Ms Dawson is working with the NSW government, councils, major corporations, businesses and community groups in producing a resilience strategy.

The commercial office sector can help

One sector that may be able to help with the strategy is the commercial property sector. As one of the biggest energy users in the city, commercial buildings can be a big drag on the grid during heatwave events.

Excessive demand can threaten blackouts across the network (though it’s usually due to residential evening use), as happened in South Australia and was threatened to occur in NSW.

But technology is helping to keep commercial buildings cool while reducing the amount of energy used at peak times, which also helps at the hip pocket.

Buildings Alive chief executive Craig Roussac said that by being more proactive buildings could save thousands a month while helping avoid blackouts and supporting the transition to a more sustainable grid.

His company has been working with 36 large commercial offices in the Sydney CBD to help them manage and understand peak demand. With maximum daily temperatures having climbed higher than previous summers by 2°C, he said it was important for commercial properties to think about how they’re operating.

“It’s no longer an option for anyone to blithely ignore network peaks,” he said. “Demand is getting more ‘peaky’ and blackouts are deadly.”

Mr Roussac said 18 of the 36 Sydney buildings he had worked with had achieved lower peaks in energy demand than during in the milder summer last year.

“This is good for the environment and good for network stability.”

The company’s platform provides alerts on upcoming weather events three days in advance so facility managers can make appropriate plans.

Mr Roussac provided an example of how one building had dealt with Sydney’s heatwave on Friday February 10.

Early morning precooling was implemented, with energy use rising between off-peak hours of 6:00am-7:00am. This means less cooling energy will be needed later when energy is more expensive and in more demand.

Buildings Alive building services engineer Mike Case said temperature set point adjustment was another technique buildings could use to reduce energy use during heatwaves. Ironically, this can result in more comfort to occupants because they tend to “dress for the weather” during heatwaves, and there won’t be as much “thermal shock” going from outside to inside.

Other techniques include turning off loads that don’t need to be on, such as decorative lighting.

With heatwaves potentially extending for days, Mr Roussac said there was danger of thermal mass heating up inside buildings, making cooling more difficult. Under these conditions, he recommends night purging of excess heat, if the outside temperature is lower than the indoor temperature.

Mr Roussac said commercial buildings shouldn’t forget the benefits of general efficiency upgrades in reducing energy demand, such as insulation, high-performance facades and lighting that doesn’t add significantly to heat loads. 

BuildingIQ is another technology platform that offers a cloud-based platform for managing commercial building energy use. Precooling is also a primary strategy for BuildingIQ. 

“For periods of extreme stress on the power grid, BuildingIQ’s system pre-cools at the lowest energy cost/highest availability, and then has the building ‘drift’ as long as possible,” vice-president of sales in Australia and New Zealand Roy Arindam said.

“So, during the heatwave, the building’s energy use is a very smooth sine wave going from cooling mode to the upper boundary of acceptable temperature and back. We can achieve a smooth, virtually undetectable cooling/drifting curve because our system can control temperature zones in real time.”

The benefits of such technology in terms of dealing with heatwaves would be most beneficial if it were widespread in use and included a range of generation technologies.

“In a truly smart city with mixed generation, our service would be able to anticipate, and guide, which power source would be most beneficial,” Mr Arindam said.

“For instance, in the presence of both solar and battery storage, we would know that cloud cover is expected at the peak heat hours of the day. In such an instance, we may instruct the solar generation system to charge the batteries during the early, less costly part of the day’s heat hours while we cool using power off the grid.

“When the hottest hours occur and it’s cloudy, we’d now have battery power to allow us to drift across the highest demand part of the day. This scenario is something we call ‘dynamic demand response’, where instead of just utilising utility demand response signals, we are adding solar availability, weather analysis, solar integration and battery storage information to optimise energy consumption based on power source.”

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