Editing Trombe wall (section)

== How Trombe walls work ==
Unlike an active solar system that employs hardware and mechanical equipment to collect or transport heat, a Trombe wall is a passive solar-heating system where the thermal energy flows in the system by natural means such as radiation, conduction, and natural convection. As a consequence, the wall works by absorbing sunlight on its outer face and then transferring this heat through the wall by conduction. Heat conducted through the wall is then distributed to the living space by radiation, and to some degree by convection, from the wall's inner surface.<ref name="Mazria1979"/>

The [[greenhouse effect]] helps this system by trapping the solar radiation between the glazing and the thermal mass. Heat from the sun, in the form of shorter-wavelength radiation, passes through the glazing largely unimpeded. When this radiation strikes the dark colored surface of the thermal mass facing the sun, the energy is absorbed and then re-emitted in the form of longer-wavelength radiation that cannot pass through the glazing as readily. Hence heat becomes trapped and builds up in the air space between the high heat capacity thermal mass and the glazing that faces the sun.<ref>{{cite web |last1=Reardon |first1=Chris |last2=Mosher |first2=Max |last3=Clarke |first3=Dick |title=Passive Solar Heating |url= http://www.yourhome.gov.au/technical/pubs/fs45.pdf|archive-url=https://web.archive.org/web/20130502231120/http://www.yourhome.gov.au/technical/pubs/fs45.pdf |archive-date=2013-05-02 }}</ref>

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.<ref name="Lechner" /> So, if there is enough mass, the wall can act as a radiant heater all night long. On the other hand, if the mass is too thick, it takes too long to transmit the thermal energy it collects, thus, the living space does not receive enough heat during the evening hours when it is needed the most. Likewise, if the thermal mass is too thin, it transmits the heat too quickly, resulting in overheating of the living space during the day and little energy left for the evening. Also, Trombe walls using water as a thermal mass collect and distribute heat to a space in the same way, but they transfer the heat through the wall components (tubes, bottles, barrels, drums, etc.) by convection rather than by conduction and the convection performance of the water walls differs according to their different heat capacities.<ref name="Myers1984" /> Larger storage volumes provide a greater and longer-term heat storage capacity, while smaller contained volumes provide greater heat exchange surfaces and thus faster distribution.