Solar Chimney Can Save Lives in a Building Fire

Solar chimneys can not only save energy but also lives, a study finds. Researchers in Australia say a properly designed solar chimney radically increases the amount of time people have to escape the building during a fire – extending the safe evacuation time from about two minutes to over 14 minutes.

The latest must-have in green building design, solar chimneys can slash energy costs up to 50%.

What is a solar chimney? It’s a passive solar heating and cooling system that harnesses natural ventilation to regulate the temperature of a building. The passive design approach operates on the well-known principle that hot air always rises.

Modern solar chimneys usually feature a wall of glass next to a wall that is painted black, to maximize the absorption of solar radiation. Vents at the top and bottom control the airflow in and out of the chimney for heating or cooling.

With an estimated 19% of the world’s energy resources going to heating, ventilating and cooling buildings, integrating solar chimneys into new builds and retrofitting to existing structures offers great potential for reducing this massive environmental cost.

Researcher Dr Long Shi of RMIT University said solar chimneys have well established environmental credentials, but their potential for improving fire safety had not been explored.

“In an emergency situation where every second counts, giving people more time to escape safely is critical,” Shi said. “Our research demonstrates that solar chimneys offer powerful benefits for both people’s safety and the environment.

“Delivering on two important functions could boosts the already strong cost-effectiveness of this sustainable technology,” Shi said.

Its boosters say the solar chimney is an ingeniously simple concept that is relatively cheap to retrofit and adds almost no extra cost to a new building, but can drive energy consumption down.

Hot air rises and is vented out of the top of the chimney, which draws more air in at the bottom, driving ventilation through a building to naturally cool it down.

During a fire, the same principle – hot air rises – enables the solar chimney to suck smoke out of the building.

Less smoke means better visibility, lower temperatures and reduced carbon monoxide – all of which contribute to increasing the amount of time people have to safely evacuate.

The research, ‘Solar chimney for a real building considering both functions of energy saving and fire safety – a case study’, with co-authors Anthony Ziem, Jie Li, Professor Kevin Zhang and Professor Sujeeva Setunge, is published in Energy and Buildings (DOI: 10.1016/j.enbuild.2020.110016).