Heating and cooling commercial and residential buildings takes a lot of energy. According to Forbes, in 2011, hot water, space heating, and cooling accounted for about half of global energy consumption across all buildings. As the global community attempts to become as efficient and sustainable as possible, new technologies are constantly being created to help reduce energy usage as much as possible.
Sometimes, however, the best technologies don’t require the ability to see into the future but, instead, to see into the past. Take the new system researchers at Lund University and the German University in Cairo created to heat and cool homes in semi-arid climates without using any power. The system is based on a 19th century idea known as the Trombe wall, which works like a mini greenhouse attached to an exterior wall of a building. It uses glass, some wooden shutters, and a little bit of dark colored paint to trap short wavelength sunlight, store thermal energy, and use it to heat the air in the room behind the wall via conduction.
This new take on the Trombe wall includes vents, so it can be used to passively cool a building, as well. The new Trombe wall managed to reduce the energy used for heating by 94 percent and the energy used for cooling by 73 percent when it was tested in a residential building.
In order to give the wall the ability to acclimate to a variety of temperatures, there are adjustable vents in the stone wall leading to the house, shutters on the outside of the glass to help prevent overheating, and insulating wool blankets that can be added removed as needed.
The exterior structure of the Trombe wall doesn’t take up much space either as, thanks to its tall, narrow shape, the stack effect causes rising hot air to be replaced by cold air. The design is not being patented and the team is actually teaching people how to use and install Trombe walls for themselves.