cool roof

Action on sustainable cooling starts with passive measures

By Kurt Shickman, Executive Director, Global Cool Cities Alliance
Opinion

Surviving and thriving on a rapidly warming planet is one of the top economic and social challenges facing the world today. The popular response to that challenge has been to install air conditioners to cool indoor spaces. Thanks to the work of organizations like Sustainable Energy for All (SEforALL) and the International Energy Agency, we are starting grasp the scale of the problem that this type of active cooling poses.

As the IEA reported in its Future of Cooling report, the demand for new air conditioning requires new electricity generation capacity equivalent to the installed base in the United States, Europe and India combined. And would cost several trillion to build. Even with that massive investment, energy demand for cooling is rising far more rapidly than our ability to construct new electric generation, straining power grids and stalling efforts to deliver energy access at the last mile. This is called the “cooling crunch.”

There is also a real human cost to active cooling, at least with our current technologies. Air conditioning generates waste heat, which means that the act of making an indoor space healthier and more comfortable has the perverse effect of making the outdoors hotter and less safe. Air conditioning can add 1 to 2°C to nighttime air temperatures in cities.  

The economic and human costs rising temperatures is staggering. SEforALL estimates that in 54 high-impact countries, economic loss to heat stress is already USD 630 billion annually, and the World Health Organization estimates that heat will result in 250,000 deaths a year by 2050 – and that doesn’t count the other health effects of heat stress.

Building cleaner, more efficient and climate friendly air conditioners is one way of solving this problem. The types of solutions supported by the Global Cooling Prize will be crucial when they can be commercialized and broadly adopted. But what do we do in the meantime?  

The answer is passive cooling measures.  

Passive cooling refers to a broad range of building materials and natural solutions that reduce indoor air temperatures and, when deployed at scale, outdoor air temperatures as well. Many passive cooling techniques are updated versions of historical building and design practices. For example, light-coloured roofs and walls were used to keep homes cool by the ancient Egyptians and Sumerians. Water features and building design to encourage air flow are hallmarks of traditional architecture across the Middle East and North Africa.  

The Cool Cities Primer recently published by The World Bank’s Energy Sector Management Assistance Program details many passive cooling options and provides examples of good policy implementation from around the world.

Passive cooling delivers benefits to people on both sides of the cooling crunch. For people who have or will soon have access to air conditioning, passive cooling is an energy efficiency investment that can reduce cooling energy demand up to 20 percent on average. For those that lack access to active cooling, passive solutions reduce indoor air temperatures by an average of 3-5°C (with some demonstrations showing a 9°C reduction). If deployed at scale, these solutions could save lives and cool whole cities.  

The reality is that rising temperatures have negative effects on just about every urban system, from transportation disruptions to school performance. Conversely, passive cooling measures would have far-reaching co-benefits that support many urban and national goals, such as improved human health, enhanced productivity, better stormwater management, improved air quality, reduced pressure on the city’s electricity system and lower GHG emissions.  

SEforALL’s Chilling Prospects series highlights the importance of cooling for achieving most of the Sustainable Development Goals, and urban passive cooling solutions can also help countries achieve their Nationally Determined Contributions under the Paris Agreement.  

Accordingly, the international community has started to take note of the opportunity of passive cooling. The Kigali Cooling Efficiency Program are supporting a number efforts to accelerate the use of passive cooling, including a project called the Million Cool Roofs Challenge. The Challenge supports 10 teams based in countries experiencing an acute lack of access to sustainable cooling. These teams are competing to install the most new, high-quality cool roofs, raise awareness, and catalyse policy development to spur markets for passive cooling solutions.  

Despite the incredible challenges of building new markets during a global pandemic, the teams have established demonstration projects that have spurred interest from local and national leaders in their countries. In one country, the team’s demonstrations and outreach led to a shift in procurement for a major national agency that will result in approximately 700,000 square metres of new cool roofs.  

Many of the teams are finding that the economic benefits of passive cooling are the key factor driving interest among local and national leaders. Installing cool roofs is an accessible job for a variety of skillsets that requires a local labor force. Some teams have further generated jobs and economic activity by producing cool roof products themselves, a point of pride amongst local leaders that has led to serious plans to update local building codes to include cool roofs.  

As a technical advisor to the teams competing in the Challenge, I’ve marveled at their ability to make such progress over this last year. It speaks to their hard work, but also to the obvious need we have globally to develop cooling solutions that benefit everyone.  

While the challenge of heat is great, a concerted global effort to tackle it with better air conditioning and passive cooling measures would be a potent response. How potent? A new report from the Los Angeles Urban Cooling Collaborative found that investments in cool roofs and green infrastructure would delay the warming effects of climate change by decades in the city.  

A delay in warming from a relatively simple transition would buy the world time to make the more complicated and challenging transitions we’ll need to survive and thrive into the future.  

Join the conversation and learn about sustainable cooling solutions with #ThisIsCool.  

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