education and competence center for organic farming grottenhof

urban planning concept
the grottenhof is intended to become a regional and supra-regional education and competence center for organic agriculture. this requires the modernization of educational and living spaces for students as well as marketing, information, and recreational areas for the interested public.
the planning task includes a new building for classrooms, administration and service areas, a multipurpose hall, and a marketing area (bio-café with sales space), as well as the renovation of the historic school building for the boarding school.
site-specific conditions, such as the prominent solitary historic building, the urgent preservation of the impressive tree stock, and the peculiarities of the topography, strongly determine the design. additionally, an optimal connection between new and old must be created.
for the necessary connection of the new building to the historic structure, the existing large-crowned hornbeam is significant. a direct central connection to the main staircase of the central risalit would endanger the tree. for this reason, two lateral “bridges” are planned, embracing the impressive hornbeam, connecting to the two side risalits.
this results in a tree-shaped, north-facing, ground-floor open courtyard—the market yard—an ideal location for markets and events of all kinds.

architectural concept
the new building presents as a compact volume with two connecting arms to the historic building.
the ground floor hosts a foyer, multipurpose hall, bio-café, and dining areas, forming a generous spatial landscape with flexible partitions and strong visual connection to the market yard terrace.
the deliberately visible kitchen, with its own delivery access and staff entrance, closes the market yard to the south. the sports area locker rooms allow direct access to the grass sports field. an external entrance to the multipurpose hall could also be provided here.
the upper floor of the new building allows two connections to the historic building and accommodates administration, teachers’ workspaces, and a spacious gallery overlooking the double-height multipurpose hall.
in the second, more private section of the upper floor, two clusters of classrooms are located, complemented by two covered outdoor classrooms.
market yard, balconies, terraces, and large staircases with seating steps provide direct outdoor access from all floors.
the central locker room in the basement of the historic building is accessed via the existing market yard entrance. the two new staircases separating old and new buildings allow short circulation paths to the new classrooms. the central locker room functions as a sluice with separate clean and dirty areas without intersecting circulation paths.
boarding school rooms are consistently located in the historic building, largely respecting the existing structure. common rooms are placed on the ground and second floors. in the first-floor connecting elements, covered terraces offer outdoor spaces for boarding students.

open space
the market yard is the central outdoor space for all kinds of events, ideal for a weekly market. the connecting path to the existing buildings is flanked by the teaching garden. the small required sports field with an outdoor arena is also located here.
teacher parking and kitchen deliveries are situated to the south, with the option for an additional internal access route.

structural concept
the three-storey main volume of the new building (dimensions approx. l / w / h = 47.5 m / 26.3 m / 12.3 m) faces the grottenhof to the west and is connected to it via a two-storey building “arm” to the south and a single-storey “bridge” to the north. at the ends of the bridge, emergency staircases are provided (dimensions approx. l / w / h = 24.6 m / 9.1 m / 8.0 m).
on the west side, the new building is cut into the sloping terrain by approx. 6.0 m; toward the historic building, a protected courtyard is formed by the added spatial ensemble (with the central tree stock), which also connects to the open space to the north, below the bridge.
the new building is generally not basemented, except for the southern building arm, which includes a basement with technical room and laundry, accessible directly from the historic building via the emergency staircase.
the load-bearing components of the new structures are designed as “hybrid”: foundations (slab foundations, strip foundations for the bridge) and all ground-contact elements in reinforced concrete, including the wide-span slabs above the gymnasium tract (beam spacing 6.0 m).
upper floors and “side buildings” are designed in timber construction, supplemented where appropriate by reinforced concrete and steel elements (columns, beams).
the structure is braced using the existing walls and, where required, supplemented with steel pipe braces. all slabs are designed as shear-rigid.

building services
the building will be heated using well water and a water-to-water heat pump.
heat is distributed at low temperature via underfloor heating. the same system can be used for cooling without operating the heat pump (change-over).
during the heating season, supply air is pre-tempered using a high-efficiency heat recovery system.
to avoid summer overheating, supply air is cooled directly via the well water (change-over).
air is pre-tempered (warm/cold) and supplied to the classrooms, eliminating drafts. it then flows through transfer openings into the corridors and is extracted in the locker rooms.
this ensures optimal air exchange and low co₂ concentration, maintaining good indoor air quality.

fire protection and escape concept
the building is used as a school with an adjoining boarding facility, so planning adheres to the building code, oib guidelines 2 and 4, and workplace regulations. the building is classified as class 4 due to its geometry.
fire compartments in the new building are arranged vertically. a maximum net floor area of 800 m² is maintained for the underground level. in the upper floors, fire compartments extend across three floors.
in the school area, the allowable compartment size of 1,600 m² is exceeded by approx. 20%, which is compensated by the installation of a fully automatic fire detection system (full protection).
up to three staircases with smoke extraction openings are available for evacuation. these are positioned to ensure a maximum escape route of 40 m from the farthest point to a staircase or outdoors. the common escape route is limited to 25 m. additionally, due to the topography, direct outdoor access from each level of the new building is possible.
in the boarding area, up to three staircases are available to level 1. for level 2, in addition to the protected emergency staircase, access for firefighting equipment is ensured for a maximum of 30 occupants.
furthermore, access routes for emergency personnel, fire safety plans, firefighting aids, emergency lighting, and provisions for regular inspections and maintenance by a qualified fire safety officer are implemented.