According to RMIT, solar chimneys can not only slash energy costs of up to 50 percent, but new research reveals they could also help save lives in a building fire.

In the new collaboration between RMIT University and the City of Kingston in Melbourne, researchers designed a solar chimney to maximise its efficiency for both ventilating fresh air and sucking smoke out of a building in case of fire.

Modelling shows the specially-designed solar chimney radically increases the amount of time people have to escape the new building during a fire – extending the safe evacuation time from about two minutes to over 14 minutes.

A solar chimney is a passive solar heating and cooling system that harnesses natural ventilation to regulate the temperature of a building.

A solar chimney is a passive solar heating and cooling system that harnesses natural ventilation to regulate the temperature of a building.

With an estimated 19 percent 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.

While calculations around the 6-fold increase in safe evacuation time were specific to the new building, previous research by the team from RMIT’s School of Engineering has confirmed solar chimneys can successfully achieve both functions – ventilation and smoke exhaustion.

The passive design approach behind solar chimneys 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 maximise the absorption of solar radiation. Vents at the top and bottom control the airflow in and out of the chimney for heating or cooling.

As the sun warms the chimney, this heats the air inside it.

The 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.

When it’s cold outside, the chimney can be closed, to direct the absorbed heat back into the building and keep it warm.

It’s an ingeniously simple concept that is relatively cheap to retrofit and adds almost no extra cost to a new build but can drive energy consumption 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.

RMIT researcher Dr Long Shi says 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,” says Shi.

“Our research demonstrates that solar chimneys offer powerful benefits for both people’s safety and the environment.”

Images: Intechopen & Mobile Home Repair

Branko Miletic

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