One of the three basic passive systems is the compilation system, combining direct and indirect way of heating rooms with solar radiation. It depends on this, that the sun's rays penetrate through the glazing and, thanks to the greenhouse effect, heat the glazed space of various sizes and functions. this space, fully glazed on the south side, it is proposed to be called a greenhouse (The. conservatory). A greenhouse can perform a variety of functions: from unusable spaces "A", through communication spaces: glass-encased vestibules, corridors, staircases, halle, balconies or loggias "B", up to the spaces combined with the living room, attached to the living room, enclosing the entire southern facades, built over the house as a glass roof, finally enclosing the entire residential volume "C".
The most interesting, for practical and aesthetic reasons, is a greenhouse that serves as a greenhouse or conservatory (The. green house). It enables year-round cultivation of vegetables and ornamental plants, it also becomes a source of more humidified and ionized air. The functional and architectural values of these glass parts of the house are undeniable. They create opportunities to expand and complete the living room space with a new green (alive) a zone that is an intermediate space between the open (outside) and closed (inside) part of the house. There are three options for combining the greenhouse with the volume of the living room:
1) on the principle of total connection with the living room,
2) on a greenhouse basis, which can be temporarily separated from the living room space,
3) on the basis of a separate extension.
Greenhouses being a superstructure above the residential part, or covering the entire usable volume, they can also be used as a space enabling year-round cultivation.
Greenhouse, apart from architectural and functional values, will always be an energy and construction problem.
Among the basic construction problems related only to glass, the most important thing:
— elimination of reflections — the possibility of using slightly structural glasses in some parts, np. Albarino - Germany,
— protection against snow load — thickened windows;
if the roof pitch is ≥ 60°, this load is not taken into account,
— protection against hail and other mechanical loads — in horizontal and diagonal parts — thicker glass, finely spattered or glued (VSG and ESG - Germany),
— glazing protection against wind pressure and suction, thermal movements,
Transparent plastics are also produced, which can be used to build greenhouses (very common in Japan): rigid, double-layer ribbed plexiglass or PVC sheets, but their durability is much less than that of glass.
The greenhouse must act as an efficient solar collector. For this purpose, it should be glazed with glass with a high coefficient of solar energy conductivity to the inside and at the same time with a low heat transfer coefficient kex - operational, including temporary heat shields. Therefore, glass panes glued or welded with rarefied gas inside or double glazing made of two panes mounted independently are used. (lower insulation, the possibility of dust and steam penetration into the space between the panes). Various types of welded or glued glass are already offered on the market of Western countries (newer) with the coefficient k = 3 W/m2K, specially adapted for the construction of greenhouses. Special glued glass panes are offered for building horizontal or slanted surfaces, which have the upper surface of the glass protruding in front of the outline of the glass o 1,5 cm, so they can be tiled, no special insulation, resting the longitudinal edges on the greenhouse structure.
In an experiment carried out in Hannover, the temperatures in a greenhouse glazed with single and double glazed glass were compared. The average temperature in a poorly insulated greenhouse over the three winter months was -1.5°C, and in a well-insulated greenhouse +7°C.
In order to reduce heat loss within 16 sunless hours of the day, In addition to double glazing, various types of curtains and screens are used, mounted in special guides under the panes, which in the summer can also protect the greenhouse from overheating.
The greenhouse is to be a device supporting the heating of the house, but the reverse cooperation should also be provided for - heating the greenhouse by heat penetrating from the inside of the house in order to protect the plants against frost. Excess heat obtained in the hothouse in spring, in summer or autumn it can be discharged to heat storage or directly to house heating. In this way, the greenhouse will not be allowed to overheat. You can also put materials with a high heat capacity in the greenhouse (massive walls, water containers, containers with phase change chemical materials), which delay the heating time of the greenhouse during the day, giving off excess heat at night, which maintains a fairly balanced temperature inside.
From the point of view of the architect-designer, the angle at which the main part of the glazing should be set is also important, because the more the angle of incidence of the sun's rays on the glass moves away from the right angle, the greater part of the direct rays are reflected. So it is important, to decide at what time of the year the greenhouse should generate maximum profits.
In our climate, it is rather impossible to determine the optimal size of a greenhouse in relation to the volume of the building. Its size and form are rather a function of the purpose and architectural solution of the entire building, and not a priori of the planned heat balance. This balance can be pre-calculated after at least the architectural concept has been completed.