How Brisbane’s floods can be a catalyst for resilience

Working on climate adaptation, resilience and emissions reduction is part of every day for Cundall Brisbane’s engineering and sustainability experts. The experience of recent severe weather events and associated flooding have added a new urgency to the work.

This is what we believe - approaching future developments with the same design methodologies that left our communities vulnerable to severe weather and flooding in 2011 and 2022 will do nothing more than guarantee we remain vulnerable in future. Rebuilding like-for-like will not be good enough - there needs to be an imperative to ensure the reconstruction and clean up results in a better, more resilient built environment.

While both of us considered the available flood mapping for Brisbane when deciding where to live, many of our friends and family did not have that choice. And despite the available data from organisations including the Bureau of Meteorology, CSIRO and Councils which shows the vulnerability of many parts of all our capital cities to the twin threats of terrestrial flooding and sea level rise, there continues to be significant development in high-risk areas.

One of the concerning aspects of the recent floods is the way in which section of the community and in leadership positions responded in the same way they did during the 2010-2011 flooding. The all-important conversation about how to adapt the city has not been had – and it must be.

Rising temperatures, increased flood risk, bushfires and other severe weather events jeopardise the reliability of infrastructure, affect efficient operation of assets, and impact businesses and livelihoods at all levels. So, there is a need to consider every aspect of the urban domain – where we build; what we build; how we provide power and ensure communications remain viable; how we supply water and how we ensure people can stay healthy and comfortable when temperature and humidity are both high.

Passive design is part of the solution: fine-tuning orientation, shading and building fabric. This includes details such as using light-coloured roofs in the hotter climate zones. The climate adaptation task is complex and multi-faceted – and there is a human dimension to that also. In 21st century Australia, people expect to be comfortable indoors at around 20-21 degrees with low humidity, year-round. This is a reasonable new phenomenon – 30 or 40 years ago most people had greater tolerance for seasonal weather, and cooling [and heating in colder climates] was generally only used to the extent it addressed and prevented extreme discomfort.

But the major uptake of air conditioning in the past 20 years or so has meant a major increase in overall energy use - even though air conditioning has become more energy efficient, there is a much larger amount of space overall being conditioned which continues to increase.

Passive design can reduce the need for mechanical systems, but there is also a need for people to develop more psychological tolerance of variations in indoor climate within a certain temperature band that is not contrary to wellbeing.

One thing passive design at this point cannot prevent is the impact of humidity; a seasonal issue in the subtropics and tropics where air conditioning is currently the most practical mitigation. To utilise air conditioning when needed for humidity control without continuing to grow pressure on the energy system means putting all the pieces together – passive design to reduce heat gain, energy-efficiency, and adaptive thermal comfort. Changing our ideas about what is tolerable is also key.

Disasters offer an opportunity to consider how we could build back better. We're fortunate to live in a place and time where we have almost-continuous access to clean water and reliable power, and we take our infrastructure for granted until the moment it's not available.

We can see a time when climate change effects are being experienced frequently and an increasing interest in resilience will be adopted as a kind of "typical" approach to buildings.

In Brisbane, two key elements are crucial for flood resilience which can be incorporated at a building level – backup water and power.

Rainwater capture needs to be designed in. Two major water treatment plants in the SEQ region went offline during the recent flooding event as a result of flooding washing soil and debris into the creeks and waterways flowing into the treatment plant. This had a significant impact on the quantity that could be supplied into the water grid for two to three days.

Rainwater being captured and used for purposes such as flushing amenities means we are not using potable water for those purposes, which reduces pressure on the water grid. If we're not putting as much pressure on the drinking water infrastructure during a disaster, then we’re saving drinking water for drinking – a better outcome for the community.

Backup power sources are also essential, and integrated thinking could see renewable energy such as solar in conjunction with storage in the form of an electric vehicle with sufficient battery capacity negating the need for diesel generators for many properties.

Microgrids can also be part of the solution. They add redundancy to protect communities from the impact of shocks and stresses that frequently occur not only due to disaster-scale weather but also heatwave energy demand peaks, damage to local infrastructure, or equipment malfunctions.

Unfortunately, climate change projections suggest our infrastructure will be subject to increasingly frequent and more extreme shocks and stresses in the future. It’s important that we extract some good out of the current disaster and use it to focus our attention on what it means to build resilient communities.

Engineers are at the centre of many decisions being made about how we develop our urban places, and we have the knowledge to transform them into resilient and restorative cities.

That is the challenge - and the opportunity - of our work.

We need practical tools to help our cities adapt to climate change – but cities themselves also need to BE the tools that help us battle climate change.

A key part of the transition will be partnership across our typical divides – we aren’t going to solve such multifaceted problems restricted to our usual silos. We need collaboration across sectors; and we need cooperation between government, industry, education, business and the community.

Climate destabilisation and global heating are not some distant prospects. It is happening right now, and the impacts are escalating. Ignoring the problem is not an option for us as professional problem-solvers.