The bioclimatic greenhouse

The bioclimatic greenhouse is an intelligent solution, aimed at thermally improving the building system to which it is applied. This component represents one of the most widespread interventions in the design conducted according to the principles of sustainability. During the design process, in fact, one of the primary objectives is to contain energy consumption, through the conscious management of environmental resources, with a view to ensuring a high level of living comfort for users. In fact, thanks to this system, residential environments are heated naturally, ensuring significant savings in economic and energy terms. 

Contents

• What is a bioclimatic greenhouse and why choose it? 
• How to navigate the regulations for installing a bioclimatic greenhouse
• The most common types of bioclimatic greenhouses      
• Solar City in Linz: a village shaped on the bioclimatic greenhouse

Yet, even if they represent very widespread practices, the choice and installation of a solar greenhouse require technical knowledge and professional awareness. For this reason, it is best to consult an expert in the sector and, in any case, be aware of the properties and characteristics of this solution, in order to choose the most suitable type for the building to which it must be anchored. Furthermore, it is necessary to act in compliance with the regulations in force in the territory in which you operate, so as not to encounter problems in the installation and free use of the capturing greenhouse.                                                                            
Below, a short guide to implement the most appropriate choices and the illustration of some examples that demonstrate how the bioclimatic greenhouse can prove to be a highly performing solution.

What is a bioclimatic greenhouse and why choose it?

The architectural design sector is showing a growing interest in issues related to energy efficiency. Current design solutions have as their primary objective the containment of consumption and management costs of the building. The use of traditional air conditioning systems, considered too expensive, is progressively replaced by solutions that maximize the use of renewable resources and are able to provide concrete benefits. Among the measures studied to improve the performance of the building, one of the most widespread is represented by the bioclimatic greenhouse which consists of an enclosed space, also called a buffer space, equipped with glass walls.

This component contributes significantly to the heating of the house, thanks to its ability to accumulate heat from the sun's rays incident on its glass surface. The solar greenhouse can be made entirely of transparent walls but often the covering is characterized by opaque materials, in order to avoid excessive overheating during the summer season. Its operation is typical of passive solar systems which store solar heat and then transmit it to the internal adjacent environments. Thanks to its versatility, the greenhouse can be inserted in residential, school, commercial and tertiary buildings. One of the essential conditions for its correct functioning is represented by the orientation, preferably towards the south. In fact, this front is the one most exposed to the sun's rays and for this reason it offers the right conditions to guarantee a higher level of living comfort throughout the year.

In fact, with the changing seasons it is necessary to know how to use the greenhouse system, optimizing its properties. If in winter it is preferable to keep the windows closed to favor the accumulation of heat and reduce heat loss, during the summer season, in order to avoid excessive overheating, it is good to be able to open them and provide shading systems additional elements, such as curtains and plant elements. Furthermore, it is important to remember that the screens must not be fixed but mobile, so that they can be moved according to seasonal needs. As regards the optimization of internal temperatures, it is also necessary to carefully choose the colors of the finishes, as these are elements that can affect thermal comfort. For example, a light-colored floor can guarantee the containment of excessive heat thanks to its high reflective capabilities.
Among the peculiarities that distinguish the bioclimatic greenhouse, it is good to remember that at least three of its sides must be made of glass and there must not be any type of air conditioning system inside.
From the point of view of materials, they are carefully chosen in order to ensure versatility, functionality and long-lasting resistance. To this end, PVC, aluminum and wood will be perfect for the profiles, while for the actual panels it will be better to opt for low-emissivity glass that excludes heat dispersion towards the outside.

Among the numerous advantages provided by the capturing greenhouse, we can include the reduction of the building's energy needs which can reach 25% with a consequent economic saving. Furthermore, by functioning as a solar gain system, this component significantly increases the level of internal thermal comfort. Another aspect that should not be underestimated is the fact that the greenhouse is considered a technical room and for this reason its size is not a determining factor for the volumetric consistency of the building, even though it can be used as an additional room to those of the house.

Furthermore, in addition to being a very bright space that can be used as a living room or study, it also represents a connecting element between the context and the building, creating a sort of continuum between the natural environment and the confined one. According to this perspective, the solution must be conceived as an active element that contributes to the organization of the home's environments, enriching them. For these reasons, the habitable bioclimatic greenhouse contributes to significantly increasing the economic value of the apartment, giving a strongly connoted image to the entire building.

How to navigate the regulations for installing a bioclimatic greenhouse

Having established that the solar greenhouse represents an element of the envelope useful for the control of thermo-hygrometric flows and for the improvement of living comfort, it should be specified that before making any type of decision it is good to know the laws that regulate its installation. Currently at a national level there is no single Privacy Policy but each Region applies specific provisions, however some principles are valid throughout the Italian territory. Two of the most important aspects concerning the greenhouse and which also determine its correct functioning, are its orientation and its position. In this regard, the north-south axis with a south-facing view is preferable.
It is also necessary to respect precise distances from the borders that can sometimes vary from municipality to municipality, depending on the geomorphological characteristics of the place. From a dimensional point of view, the net surface of the bioclimatic greenhouse cannot exceed 15% of the total surface of the building in question. Furthermore, in some Italian municipalities there are specific provisions regarding the maximum depth that the solar greenhouse must have.

Another essential aspect concerns the benefits that each greenhouse must be able to ensure, first of all the reduction of at least 10% of the energy requirement for winter heating. This is an objective that must be achieved without the aid of air conditioning systems but only through the bioclimatic behavior of this passive solar system. In addition, the capturing greenhouse must be managed correctly throughout the day, in order to avoid climate discomfort, due to low performance in winter and overheating in summer.

In this perspective, it is important to choose the technological solutions suitable for this purpose and opt for low-dispersion materials and mobile screening systems. In any case, if you want to install a bioclimatic solar greenhouse, you need to obtain the necessary authorizations for correct construction, checking the regulations in force at the regional level and the hypothetical changes at the municipal level. An essential prerogative is then constituted by the urban planning regularity of the building involved in the insertion of the greenhouse, subject to a specific municipal inspection.

The most common types of bioclimatic greenhouses

The bioclimatic greenhouse is a separate body that, although considered a technical room that does not affect the building's volume, has a material bulk. The position that the greenhouse assumes with respect to the building being worked on also determines its typology. In fact, bioclimatic greenhouses can be attached, built-in and semi-built-in. The solar greenhouses attached, are made up of three independent glass walls and a single vertical surface shared with the building to which they belong. In this case the roof is also made of glass and usually inclined. The second typology is represented by the Built-in solar greenhouses, characterized by sharing most of the surface with the building in question. In fact, three of the four transparent walls are shared with the building and the roof is opaque.
Finally, the third type of storage greenhouse that can be chosen according to your needs, consists of the semi-built-in greenhouse which includes the characteristics of the two previous solutions. In fact, this type of greenhouse is equipped with side walls and a roof partially attached to the building.

In these three cases, solar gain solutions are classified based on their physical characteristics. However, it is also possible to establish a typological subdivision based on their operation.
In these terms, the aspect analyzed is represented by the behavior of the solar rays and the heat transmitted by the greenhouse walls to the internal environments of the building concerned.
The first solutions consist of the direct solar gain greenhouses which, thanks to the transparency of the wall that divides them from the internal space, guarantee the direct flow of incident solar rays and the heat they produce. The heat filters and once it has passed into the internal environments it accumulates on the floor surface to be distributed at a later time.

The second typology is represented by solar greenhouses that work through the convective exchange, according to which the heat passes from the greenhouse environment to the internal environment of the living spaces. For the correct functioning of this typology, forced ventilation ducts are inserted in the upper and lower part of the wall, useful for the transmission of heat to the rooms adjacent to the greenhouse and to those further away. Finally, the third type of capturing greenhouse works with the radiant exchange where heat is transmitted into the building through an uninsulated storage wall. In this case, the transmission will occur when the confined spaces begin to cool and thus require heating.

Regardless of the type chosen, the bioclimatic greenhouse represents an excellent solution for the thermal improvement of your building. Used since ancient times to optimize the climatic conditions necessary for the growth of plant species, it has developed over time, finding wide use in different fields. In some northern European countries, solar greenhouses today constitute additional rooms for residences, thanks to which you can enjoy greater natural light and heat during the colder seasons.

To learn more about heat exchange click here

Solar City in Linz: a village shaped on the bioclimatic greenhouse

In Austria, in the city of Linz, a new residential area was inaugurated in 2001 which, thanks to the energy solutions used, earned the title of “solar urban district”. The innovative project stands out for the physical conformation of the buildings and for the measures adopted, in order to satisfy the housing need in full respect of the environment.

This is one of the most illustrious examples of a city district designed according to the criteria of eco-sustainable architecture, created with the dual purpose of achieving maximum density and good typological flexibility. The complex also includes buildings for commercial and service purposes, in addition to those purely residential.

Depending on their function, the buildings have been positioned and oriented according to an alternation of full and empty spaces, green areas and axes that connect the district with the rest of the city and the surrounding lake areas. The southern front was chosen for the residences that require a greater amount of light and heat, while the northern front mainly houses the shops and service spaces. Each building is developed on a maximum of four floors above ground and the most used materials are glass and wood that sometimes covers large surfaces on the facade, in order to maintain constant internal comfort, avoiding unpleasant temperature changes.

Solar City, the “city of the sun”, has made this natural resource a real driving force to satisfy the energy needs of the entire multifunctional complex. In fact, each building is oriented and designed to make the most of solar energy. The bioclimatic greenhouse becomes a characterizing element and is able to make the buildings self-sufficient, thanks to its passive operation. Furthermore, greenhouses are not only an added component to the building but are sometimes designed as an entrance to the residence, thus becoming a totalizing and very functional element for the entire housing complex.
To deal with excessive heat accumulation during the summer season, each greenhouse is equipped with mobile shading systems, such as curtains and sun screens and in some cases the roofs are characterized by garden roofs aimed at increasing the value of the buildings in terms of thermal insulation. Furthermore, photovoltaic systems are often present on the roofs thanks to which the exploitation of energy from solar rays incident on the surface is maximized. The contribution of these measures is aimed at complete energy independence of the multifunctional complex so that over time the neighborhood will be able to co-generate energy through the use of its own solar systems.

In some cases, the bioclimatic greenhouse constitutes a functional space used to promote social relationships and the recovery of the sense of community that has now faded in developed urban contexts. An example of this is the Kindergarten by Olivia Schimek, a building intended to house the district nursery school. The greenhouse in front of the building represents a large usable buffer space that becomes a meeting place adjacent to the play area.
The volumes that make up the kindergarten complex, in addition to taking advantage of the solar orientation and increasing the stored heat to ensure optimal internal temperatures, are characterized by high brightness thanks to the inclined glass surface on the south front. Furthermore, the structure includes a controlled ventilation system with heat recovery, thanks to which the amount of additional energy required is contained. This mechanism is able to maintain optimal thermal comfort.

To view some examples of nursery school projects click here

In other buildings, solar greenhouses are placed in correspondence with the roofs or vertical connection elements, increasing the level of ventilation and internal lighting.
In the residential complex WAG by Herzog & Partners, the glass roof in the winter season works as a bioclimatic greenhouse that stores heat, contributing to the heating of the accommodations, ensuring significant energy and consequently economic savings. In summer, the rising flows of hot air come out of the openings at the top, while the cooler air is drawn from below and in this way cools the building during the night hours.   

In addition to solar greenhouses, the residential district is represented by winter gardens, balconies and views aimed at creating a continuum between the interior and the surrounding green landscape. Solar City in Linz has proven to be one of the first large-scale projects, where particular attention has been paid to building sustainability, with the ability to combine efficiency and overall harmony.

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