The bioclimatic greenhouse

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, has earned the title of "solar urban district". The innovative project is distinguished by the physical conformation of the buildings and the measures taken, in order to meet the housing need in full respect for the environment. It is one of the most illustrious examples of a city district designed according to the criteria of eco-sustainable architecture, born with the dual purpose of achieving maximum density and good typological flexibility. The complex also includes commercial and service buildings, in addition to purely residential ones. Depending on the function they play, 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 with the surrounding lake areas. The south front was chosen for residences that need more light and heat, while the north front mainly houses shops and service spaces. Each building is spread over a maximum of four floors above ground and the most used materials are represented by glass and wood which 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 meet the energy needs of the entire multifunctional complex. In fact, each building is oriented and studied in order to make the most of solar energy. The bioclimatic greenhouse becomes a characterizing element and is able to make buildings self-sufficient, thanks to its passive functioning. In addition, the greenhouses are not just an added component to the building but are sometimes designed as the entrance to the residence, thus becoming a totalizing and very functional element for the entire housing complex.
To cope with the excessive accumulation of heat during the summer season, each greenhouse is equipped with mobile darkening systems, such as curtains and brise-soleil and in some cases the roofs are characterized by garden roofs aimed at increasing the value of the buildings in terms of of thermal insulation. In addition, there are often photovoltaic systems on the roof thanks to which the exploitation of energy from the sun's rays incident on the surface is maximized. The contribution of these measures is aimed at the 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 solar systems.

In some cases, the bioclimatic greenhouse constitutes a functional space that is exploited to foster social relationships and recover the sense of community that has now faded in evolved urban contexts. One example is Olivia Schimek's Kindergarten, 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 preschool complex as well as taking advantage of the solar orientation and increasing the heat stored to ensure optimal internal temperatures, are characterized by high brightness thanks to the inclined glass surface on the south front. In addition, the structure provides 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.

   
Solar City of Linz - Kindergarten, Olivia Schimek, 2002-2007 - Front and back of the solar greenhouse
Source:  http://www.arch-schimek.at/en/projekt/kindergarten-solarcity

To view some design examples of kindergarten click here

In other buildings, the greenhouses are placed in correspondence with the roofs or the vertical connection elements, increasing the level of ventilation and internal lighting.
In the WAG residential complex of Herzog & Partners, the glass roof in the winter season acts as a bioclimatic greenhouse which, by storing heat, contributes to the heating of the accommodation, ensuring significant energy savings and consequently economic savings. In summer, the ascending flows of hot air escape from the openings at the top, while the cooler air is drawn from below and in this way cools the building at night.

   
Solar City of Linz - Thomas Herzog & Partners, 2004 - View of residential complexes equipped with solar greenhouses
Source: http://thomasherzogarchitekten.de/en/en-2004-solarcity-gwg

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 of Linz proved to be one of the first large-scale projects, where particular attention was paid to building sustainability, with the ability to combine efficiency and overall harmony.