We can't air-condition our way out of a hotter future, says UNSW expert
UNSW Sydney
Key Facts:The paper "Passive cooling for the built environment" will be published on July 2 3pm AEST. It is attached under strict embargo.
As temperatures rise around the world, air conditioning is saving lives. But a growing reliance on it is also placing unprecedented pressure on electricity grids, increasing greenhouse gas emissions and making cities even hotter.
A global review led by UNSW Sydney's Professor Mat Santamouris AM – an expert in innovative heat mitigation technologies and strategies for cities – argues that keeping buildings cool without relying solely on air conditioning will be critical for adapting to climate change.
Published in Nature Reviews Clean Technology, the review examines the latest advances in passive cooling technologies, from emerging materials for radiative, evaporative and combined radiative/evaporative cooling to sophisticated solar control systems and personalised intelligent ventilation technologies that can help buildings shed heat without consuming electricity.
Prof. Santamouris says passive cooling should no longer be viewed as a niche architectural feature, but as essential infrastructure for a warming world.
“Air conditioning saves lives and will remain essential during extreme heat,” he says. “But we cannot air-condition our way out of climate change. If every building depends entirely on mechanical cooling, we create enormous pressure on electricity systems while adding even more heat to our cities.”
Sub-head: Demand for cooling is soaring
Demand for cooling is soaring
The review highlights the rapid growth in cooling demand worldwide. Global electricity consumption for cooling has reached almost 10 per cent of total electricity use, with around 10 new air conditioners sold every second. By 2050, the number of residential air-conditioning units is projected to increase to almost 5.6 billion worldwide.
At the same time, billions of people living in hot climates still lack access to affordable cooling.
Cooling buildings without relying on air conditioning
Passive cooling technologies offer a way to reduce energy demand while making buildings safer and more comfortable, particularly for vulnerable communities.
“The best cooling strategy is to stop unwanted heat entering buildings in the first place. Shading, reflective materials, smarter ventilation and new cooling materials can dramatically reduce indoor temperatures before an air conditioner even needs to switch on,” says Prof. Santamouris.
Rather than replacing air conditioning, Prof. Santamouris and coauthor Dr Konstantina Vasilakopoulou from RMIT argue passive cooling should become the first layer of defence, with mechanical systems providing additional cooling only when required.
The review evaluates emerging innovative technologies, such as super-cool materials, combined radiative/evaporative coatings, sophisticated external shading systems and personalised ventilation, as well as known passive cooling technologies such as reflective cooling materials that release heat directly into the atmosphere and hybrid cooling systems that combine multiple passive approaches.
Integrating passive cooling strategies with efficient building design could reduce cooling demand by as much as 80 per cent in hot climates while lowering peak electricity demand and improving resilience during power outages, according to the review.
Cooler cities, healthier communities
Beyond reducing energy use, the researchers say passive cooling can make cities healthier and more resilient as extreme heat events become more frequent.
Keeping buildings and neighbourhoods cooler can reduce the risk of heat-related illness, ease pressure on electricity networks during heatwaves and improve comfort for people who cannot afford to run air conditioners. Passive cooling measures can also help buildings remain safer during power outages, when mechanical cooling systems are unavailable.
Prof. Santamouris says the greatest benefits will come from combining passive cooling with efficient air conditioning, rather than treating them as competing approaches.
“There is no single solution to keeping cities cool. We need a whole-system approach that starts with climate-responsive building design, shading and better materials, then uses the most efficient cooling technologies only when they are really needed.”
The review calls for stronger building standards and planning policies that encourage climate-responsive design, alongside investment in technologies that reduce heat entering buildings and lessen demand on electricity infrastructure as cities continue to warm.
Designing buildings for tomorrow’s climate
Buildings designed today will need to withstand a much hotter climate over coming decades, says Prof. Santamouris.
“The buildings we construct today will still be standing in 2050 and beyond. They need to be designed for the climate they will experience, not the climate we had in the past.”
In order to achieve this governments should strengthen building standards, support passive cooling technologies and improve access to affordable cooling for lower-income communities.
Prof. Santamouris says these measures could deliver significant benefits for public health, energy security and climate resilience.
“Cooling should not be a luxury available only to those who can afford rising electricity bills. Better building design can reduce costs, improve comfort and help protect the people most vulnerable to extreme heat,” he says.
Contact details:
Prof. Santamouris is in Europe. He can be contacted for interview directly at [email protected] or Mobile +61404134975 He is -7 hours AEST.