Unlike active systems, in passive systems, special installations are unnecessary, in which the intermediate medium circulates. The role of collectors in these systems is fulfilled by glazing and elements or whole parts of houses. Solar radiation in the form of visible and infrared waves enters the interior through the glazing, in a negligible amount of ultraviolet and encounters absorbing elements specially adapted for this purpose. In one case, these are interior walls, floors and ceilings, in another, a massive or lightweight outer wall, in yet another, a massive wall separating the glazed veranda from the rest of the residential space.
The absorbing elements, while heating up, emit long-term thermal radiation, that heats the room, but it is stopped by the windows. This phenomenon is called the "greenhouse effect", which together with convective air movements, transfer and conduction, is the basis for the operation of passive solar systems.
In these systems, not only the type of glazing needs to be properly designed, swallow a color, texture and types and layers of materials in absorbent elements. Their great form, blending with the rest of the building, will be evidence of their proper use and understanding, because their efficiency is a function of the architectural and construction solution of the entire building.
Higher efficiency and efficiency of the system is ensured by mechanical distribution of passively obtained heat to the warehouses, or living quarters. Systems solved in this way are called semi-active. It is often impossible to distinguish them from active air systems.
Influence of passive systems on materials, constructions, function solution, and consequently the form of single-family houses is much greater than that of active systems, the more so that these solutions should also include other elements of energy-saving architecture. In the correct solution of technical problems, an architect can be assisted by a district heating engineer, air conditioning and ventilation. The requirements of passive systems are not that great, to unify and limit the development of architecture; on the contrary they do, that houses must be adapted to regional conditions and can always be designed in accordance with changing directions or currents.
In Polish climatic conditions and with the Polish building tradition, passive systems can be used, which will cover the heat demand on average in 20 do 60%. Thanks to these systems, the heating season can be shortened, which would run from November to March, which is a significant economic saving and ecological benefit both on the scale of the farm and the country.
The Polish system of building single-family houses is often defined, due to the materials and constructions used, as heavy or light heavy, but it is precisely this way of building that makes it easier to adapt and use it for passive solar systems. The use of passive systems causes a slight increase in the cost of building a row 10 do 15%, which is quickly amortized in the form of thermal energy gains.
The advantages of passive systems are:
— brak kosztów eksploatacyjnych,
— brak specjalistycznych urządzeń,
— łatwość i prostota obsługi,
— trwałość i niezawodność.
These advantages outweigh the disadvantages, what they are:
— zmiany w natężeniu strumienia ciepła zależne od usłonecznienia,
— pewna uciążliwość systemu zysków bezpośrednich.
Using solar radiation in a passive way to heat houses is nothing new. Constantly improved, existed in the distant past.