A Trombe wall is a massive equator-facing wall that is painted a dark color in order to absorb thermal energy from incident sunlight and covered with a glass on the outside with an insulating air-gap between the wall and the glaze. A Trombe wall is a passive solar building design strategy that adopts the concept of indirect-gain, where sunlight first strikes a solar energy collection surface in contact with a thermal mass of air. The sunlight absorbed by the mass is converted to thermal energy (heat) and then transferred into the living space.

Trombe walls may also be referred to as a mass wall, solar wall, or thermal storage wall. However, due to the extensive work of professor and architect Félix Trombe in the design of passively heated and cooled solar structure, they are often called Trombe Walls.

History of passive solar systems and evolution of Trombe walls

In 1920s, the idea of solar heating began in Europe. In Germany, housing projects were designed to take advantage of the sun. The research and accumulated solar design experience was then spread across the Atlantic by architects such as Walter Gropius and Marcel Breuer. Apart from these early examples, heating homes with the sun made slow progress until the 1930s, when several different American architects started to explore the potential of solar heating. The pioneering work of these American architects, the influence of immigrant Europeans, and the memory of wartime fuel shortages made solar heating very popular during the initial housing boom at the end of World War II.

Later in the 1970s, before and after the international oil crisis of 1973, some European architectural periodicals were critical of standard construction methods and architecture of the time. They described how architects and engineers reacted to the crisis, proposing new techniques and projects in order to intervene innovatively in the built environment, using energy and natural resources more efficiently.

Moreover, the depletion of natural resources generated interest in renewable energy sources, such as solar energy.

Parallel to global population growth, energy consumption and environmental issues have become a global concern - especially while the building sector is consuming the highest energy in the world and most of the energy is used for heating, ventilation and air conditioning systems.

For these reasons, today's buildings are expected to achieve both energy efficiency and environmental-friendly design through the use of renewable energy partly or completely instead of fossil energy for heating and cooling. In this direction, the integration of passive solar systems in buildings is one strategy for sustainable development and increasingly encouraged by international regulations.

Today's low-energy buildings with Trombe walls often improve on an ancient technique that incorporates a thermal storage and delivery system people have already used: thick walls of adobe or stone to trap the sun's heat during the day and release it slowly and evenly at night to heat their building. Today, the Trombe wall continues to serve as an effective strategy of passive solar design.

The first well-known example of a Trombe wall system was used in the Trombe house of Odeillo, France in 1967.

In 1974, the first example of Trombe wall system was used in the Kelbaugh House in Princeton, New Jersey.

Another phenomenon that plays a role in the Trombe wall's operation is the time lag caused by the heat capacity of the materials. Since Trombe walls are quite thick and made of high heat capacity materials, the heat-flow from the warmer outer surface to the cooler inner surface is slower than other materials with less heat capacity. This delayed heat-flow phenomenon is known as time lag and it causes the heat gained during the day to reach the interior surface of the thermal mass later. This property of the mass helps to heat the living space in the evenings as well.

Although the Trombe walls are usually made of solid materials, such as concrete, brick, stone, or adobe, they can also be made of water. The advantage of using water as a thermal mass is that water stores considerably more heat per volume (has a greater heat capacity) than masonry. Another strategy helps to benefit from the solar collection without some of the drawbacks of the Trombe walls is to use exterior mirror-like reflectors. However, it is recommended to use the single glass with a shutter for the evening and night times, to offset its heat losses. High transmission glazing maximizes solar gains of the Trombe wall while allowing to recognize the dark brick, natural stones, water containers, or another attractive thermal mass system behind the glazing as well. However, from an aesthetics perspective, sometimes it is not desirable to distinguish the black thermal mass. As an architectural detail, patterned glass can be used to limit the exterior visibility of the dark wall without sacrificing transmissivity. specifically using a Trombe wall in building can reduce a building's energy consumption up to 30% in addition to being environmentally friendly.

  • Similarly, the energy heating savings of 16.36% can be achieved if a Trombe wall was added to the building envelope.
  • Glare, ultraviolet degradation, or reduction of night time privacy are not problems with a full-height Trombe wall system.
  • As seen in the Trombe wall design and construction section, the performance of the Trombe walls is well characterized for a variety of design and climate parameters. Possible other modifications can be adding a rigid insulation board to the foundation area and insulation curtains between the glass and thermal mass to avoid heat transfer into the building during undesired periods or heat loss from the Trombe wall to the foundation, or adding a ventilation system into the wall system (if the wall has upper and lower vents) to provide an additional heat transfer by air convection which is desirable to circulate the air evenly. Even though Trombe walls built in hot-summer and warm-winter zones provide more energy savings per unit wall area compared to a conventional wall, they display a poorer economic performance if solar radiation is low during the heating season.
  • The system requires user action to operate movable insulation or shutters, often on a daily basis.
  • In regions where the local users are not familiar with the system, to get the maximum performance from the Trombe wall system, users can be given guidance either by modeling a prototype or providing a user-friendly operation manual for the wall during different seasons or days. This participation can lead to post-project acceptance of the Trombe wall idea and make it easier for locals to reproduce it locally.

Mitigating design variations

The Kachadorian floor overcomes the disadvantages of the Trombe wall by orienting it horizontally instead of vertically. The Barra system combines actual Trombe walls with a ventilated slab like the Kachadorian floor.

See also

  • Passive solar building design
  • Kachadorian floor
  • Barra system
  • List of pioneering solar buildings

References

  • Druk White Lotus School website including Trombe wall example.
  • Sketchup model at 3D Warehouse
  • [https://www.treehugger.com/sustainable-product-design/the-trombe-wall-low-tech-solar-design-makes-a-comeback.html] Air heater with the same working principle as Trombe wall, patented by E.S. Morse in 1881.