Increasing building fire safety with solar chimneys

Scientists from RMIT University in Melbourne and Kingston City Council investigated the impact of solar chimneys on the fire protection of buildings.

Solar chimneys are utilized to regulate the temperature of a building's interior and to provide ventilation. They are practically vertical, hollow containers linked both to the interior and the exterior of a building and they are considered a green and cost-efficient solution to maintain the temperature inside a structure at the desired levels.

Their functionality is passive and their operation is based on the fact that hot air is thinner and tends to rise. They are usually made of a glass and placed next to a black wall that absorbs the maximum amount of solar radiation. When the air inside the chimney is heated, it rises and is extracted out of the building. Therefore, the airflow that is created cools the building down and provides ventilation. On the contrary, when the air is cooled down, the chimney can be closed and all the absorbed heat is directly transferred into the building.

A new study, recently published in Energy and Buildings Journal, investigated the potential of fire protection that solar chimneys present. In particular, the scientific team designed a chimney capable of both providing ventilation and forcing out smoke when a fire strikes inside a building.

The study mentions that there has been previous research that confirms the potential of solar chimneys to exhaust smoke. Researchers utilized computer modeling, validated by experiments, to assess the performance of a typical building with and without a solar chimney.

The results showed that the designed solar chimney acts beneficially. The temperature rise and the levels of carbon monoxide during the fire are mitigated. In particular, without a solar chimney, carbon monoxide would fill a room in just 2 minutes but, when a solar chimney is operating, its levels are relatively low for more than 14 minutes. Therefore, people have more time to evacuate the structure and be directed to open space.

“In an emergency situation where every second counts, giving people more time to escape safely is critical. Our research demonstrates that solar chimneys offer powerful benefits for both people’s safety and the environment. Delivering on two important functions could boost the already strong cost-effectiveness of this sustainable technology,” Dr. Long Shi, lead author of the study and an Australian Research Council DECRA Fellow at RMIT University, stated.

The exact extent of this beneficial effect is depended on the characteristics of the building. The researchers' aim is to provide a guideline towards a sustainable engineering design of solar chimneys that will boost their utilization worldwide.