Roofing Materials Might Replace Your Home Air Conditioner

Researchers from McGill University, UCLA and Princeton have found in a new study the use of roof materials that radiate heat into the cold universe, even under direct sunlight, and how to combine them with temperature-driven ventilation could cool a home.

The need for cool living environments is becoming more urgent. But air conditioning is a major contributor to global warming since units use potent greenhouse gases and lots of energy.

Now, researchers from McGill University, UCLA and Princeton have found in a new study an inexpensive, sustainable alternative to mechanical cooling with refrigerants in hot and arid climates, and a way to mitigate dangerous heat waves during electricity blackouts. The study paper has been published in Cell Reports Physical Science, and at posting is not behind a paywall. You may want to check this material out quickly.

Upper photo is of the experiment setup in Topanga Valley, California. The lower photo shows the inside of the test box. Image Credit: McGill University. For more information click the study paper link.

The researchers set out to answer how to achieve a new benchmark in passive cooling inside naturally conditioned buildings in hot climates such as Southern California. They examined the use of roof materials that radiate heat into the cold universe, even under direct sunlight, and how to combine them with temperature-driven ventilation.

These cool radiator materials and coatings are often used to stop roofs overheating. Researchers have also used them to improve heat rejection from chillers.

But there is untapped potential for integrating them into architectural design more fully, so they can not only reject indoor heat to outer space in a passive way, but also drive regular and healthy air changes.

Remy Fortin, lead author and PhD candidate at the Peter Guo-hua Fu School of Architecture said, “We found we could maintain air temperatures several degrees below the prevailing ambient temperature, and several degrees more below a reference ‘gold standard’ for passive cooling. We did this without sacrificing healthy ventilation air changes.” This was a considerable challenge, considering air exchanges are a source of heating when the aim is to keep a room cooler than the exterior.

The researchers hope the findings will be used to positively impact communities suffering from dangerous climate heating and heat waves. “We hope that materials scientists, architects, and engineers will be interested in these results, and that our work will inspire more holistic thinking for how to integrate breakthroughs in radiative cooling materials with simple but effective architectural solutions,” said Salmaan Craig, Principal Investigator for the project and Assistant Professor at the Peter Guo-hua Fu School of Architecture.

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This is one more good idea that could or perhaps should be part of any new build or redesign.

But Professor Craig is likely the most correct by saying, “more holistic thinking for how to integrate breakthroughs in radiative cooling materials with simple but effective architectural solutions.”

Hopefully a consumer level guide book or brochure will turn up that folks can use to search for expertise.

The noticeable missing thing is the lack of dehumidifying the home. That nay not be a big deal in California, but for much of the south and middle west its a critical component for comfortable air spaces.

Venting is great, but dehumidifying with filtering might be better.

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